FileUtils (Apache Commons IO 2.5 API)

java.lang.Object
- org.apache.commons.io.FileUtils

```
public class FileUtils
extends Object
```
General file manipulation utilities.
Facilities are provided in the following areas:
- writing to a file
- reading from a file
- make a directory including parent directories
- copying files and directories
- deleting files and directories
- converting to and from a URL
- listing files and directories by filter and extension
- comparing file content
- file last changed date
- calculating a checksum
Origin of code: Excalibur, Alexandria, Commons-Utils
Version:

$Id: FileUtils.java 1722481 2016-01-01 01:42:04Z dbrosius $

Field Summary

Fields
Modifier and Type	Field and Description
`static File[]`	`EMPTY_FILE_ARRAY` An empty array of type `File`.
`static long`	`ONE_EB` The number of bytes in an exabyte.
`static BigInteger`	`ONE_EB_BI` The number of bytes in an exabyte.
`static long`	`ONE_GB` The number of bytes in a gigabyte.
`static BigInteger`	`ONE_GB_BI` The number of bytes in a gigabyte.
`static long`	`ONE_KB` The number of bytes in a kilobyte.
`static BigInteger`	`ONE_KB_BI` The number of bytes in a kilobyte.
`static long`	`ONE_MB` The number of bytes in a megabyte.
`static BigInteger`	`ONE_MB_BI` The number of bytes in a megabyte.
`static long`	`ONE_PB` The number of bytes in a petabyte.
`static BigInteger`	`ONE_PB_BI` The number of bytes in a petabyte.
`static long`	`ONE_TB` The number of bytes in a terabyte.
`static BigInteger`	`ONE_TB_BI` The number of bytes in a terabyte.
`static BigInteger`	`ONE_YB` The number of bytes in a yottabyte.
`static BigInteger`	`ONE_ZB` The number of bytes in a zettabyte.

Constructor Summary

Constructors
Constructor and Description

FileUtils()
Instances should NOT be constructed in standard programming.

Constructors
Constructor and Description
`FileUtils()` Instances should NOT be constructed in standard programming.

Method Summary

Methods
Modifier and Type	Method and Description
`static String`	`byteCountToDisplaySize(BigInteger size)` Returns a human-readable version of the file size, where the input represents a specific number of bytes.
`static String`	`byteCountToDisplaySize(long size)` Returns a human-readable version of the file size, where the input represents a specific number of bytes.
`static Checksum`	`checksum(File file, Checksum checksum)` Computes the checksum of a file using the specified checksum object.
`static long`	`checksumCRC32(File file)` Computes the checksum of a file using the CRC32 checksum routine.
`static void`	`cleanDirectory(File directory)` Cleans a directory without deleting it.
`static boolean`	`contentEquals(File file1, File file2)` Compares the contents of two files to determine if they are equal or not.
`static boolean`	`contentEqualsIgnoreEOL(File file1, File file2, String charsetName)` Compares the contents of two files to determine if they are equal or not.
`static File[]`	`convertFileCollectionToFileArray(Collection<File> files)` Converts a Collection containing java.io.File instanced into array representation.
`static void`	`copyDirectory(File srcDir, File destDir)` Copies a whole directory to a new location preserving the file dates.
`static void`	`copyDirectory(File srcDir, File destDir, boolean preserveFileDate)` Copies a whole directory to a new location.
`static void`	`copyDirectory(File srcDir, File destDir, FileFilter filter)` Copies a filtered directory to a new location preserving the file dates.
`static void`	`copyDirectory(File srcDir, File destDir, FileFilter filter, boolean preserveFileDate)` Copies a filtered directory to a new location.
`static void`	`copyDirectoryToDirectory(File srcDir, File destDir)` Copies a directory to within another directory preserving the file dates.
`static void`	`copyFile(File srcFile, File destFile)` Copies a file to a new location preserving the file date.
`static void`	`copyFile(File srcFile, File destFile, boolean preserveFileDate)` Copies a file to a new location.
`static long`	`copyFile(File input, OutputStream output)` Copy bytes from a `File` to an `OutputStream`.
`static void`	`copyFileToDirectory(File srcFile, File destDir)` Copies a file to a directory preserving the file date.
`static void`	`copyFileToDirectory(File srcFile, File destDir, boolean preserveFileDate)` Copies a file to a directory optionally preserving the file date.
`static void`	`copyInputStreamToFile(InputStream source, File destination)` Copies bytes from an `InputStream` `source` to a file `destination`.
`static void`	`copyToFile(InputStream source, File destination)` Copies bytes from an `InputStream` `source` to a file `destination`.
`static void`	`copyURLToFile(URL source, File destination)` Copies bytes from the URL `source` to a file `destination`.
`static void`	`copyURLToFile(URL source, File destination, int connectionTimeout, int readTimeout)` Copies bytes from the URL `source` to a file `destination`.
`static void`	`deleteDirectory(File directory)` Deletes a directory recursively.
`static boolean`	`deleteQuietly(File file)` Deletes a file, never throwing an exception.
`static boolean`	`directoryContains(File directory, File child)` Determines whether the `parent` directory contains the `child` element (a file or directory).
`static void`	`forceDelete(File file)` Deletes a file.
`static void`	`forceDeleteOnExit(File file)` Schedules a file to be deleted when JVM exits.
`static void`	`forceMkdir(File directory)` Makes a directory, including any necessary but nonexistent parent directories.
`static void`	`forceMkdirParent(File file)` Makes any necessary but nonexistent parent directories for a given File.
`static File`	`getFile(File directory, String... names)` Construct a file from the set of name elements.
`static File`	`getFile(String... names)` Construct a file from the set of name elements.
`static File`	`getTempDirectory()` Returns a `File` representing the system temporary directory.
`static String`	`getTempDirectoryPath()` Returns the path to the system temporary directory.
`static File`	`getUserDirectory()` Returns a `File` representing the user's home directory.
`static String`	`getUserDirectoryPath()` Returns the path to the user's home directory.
`static boolean`	`isFileNewer(File file, Date date)` Tests if the specified `File` is newer than the specified `Date`.
`static boolean`	`isFileNewer(File file, File reference)` Tests if the specified `File` is newer than the reference `File`.
`static boolean`	`isFileNewer(File file, long timeMillis)` Tests if the specified `File` is newer than the specified time reference.
`static boolean`	`isFileOlder(File file, Date date)` Tests if the specified `File` is older than the specified `Date`.
`static boolean`	`isFileOlder(File file, File reference)` Tests if the specified `File` is older than the reference `File`.
`static boolean`	`isFileOlder(File file, long timeMillis)` Tests if the specified `File` is older than the specified time reference.
`static boolean`	`isSymlink(File file)` Determines whether the specified file is a Symbolic Link rather than an actual file.
`static Iterator<File>`	`iterateFiles(File directory, IOFileFilter fileFilter, IOFileFilter dirFilter)` Allows iteration over the files in given directory (and optionally its subdirectories).
`static Iterator<File>`	`iterateFiles(File directory, String[] extensions, boolean recursive)` Allows iteration over the files in a given directory (and optionally its subdirectories) which match an array of extensions.
`static Iterator<File>`	`iterateFilesAndDirs(File directory, IOFileFilter fileFilter, IOFileFilter dirFilter)` Allows iteration over the files in given directory (and optionally its subdirectories).
`static LineIterator`	`lineIterator(File file)` Returns an Iterator for the lines in a `File` using the default encoding for the VM.
`static LineIterator`	`lineIterator(File file, String encoding)` Returns an Iterator for the lines in a `File`.
`static Collection<File>`	`listFiles(File directory, IOFileFilter fileFilter, IOFileFilter dirFilter)` Finds files within a given directory (and optionally its subdirectories).
`static Collection<File>`	`listFiles(File directory, String[] extensions, boolean recursive)` Finds files within a given directory (and optionally its subdirectories) which match an array of extensions.
`static Collection<File>`	`listFilesAndDirs(File directory, IOFileFilter fileFilter, IOFileFilter dirFilter)` Finds files within a given directory (and optionally its subdirectories).
`static void`	`moveDirectory(File srcDir, File destDir)` Moves a directory.
`static void`	`moveDirectoryToDirectory(File src, File destDir, boolean createDestDir)` Moves a directory to another directory.
`static void`	`moveFile(File srcFile, File destFile)` Moves a file.
`static void`	`moveFileToDirectory(File srcFile, File destDir, boolean createDestDir)` Moves a file to a directory.
`static void`	`moveToDirectory(File src, File destDir, boolean createDestDir)` Moves a file or directory to the destination directory.
`static FileInputStream`	`openInputStream(File file)` Opens a `FileInputStream` for the specified file, providing better error messages than simply calling `new FileInputStream(file)`.
`static FileOutputStream`	`openOutputStream(File file)` Opens a `FileOutputStream` for the specified file, checking and creating the parent directory if it does not exist.
`static FileOutputStream`	`openOutputStream(File file, boolean append)` Opens a `FileOutputStream` for the specified file, checking and creating the parent directory if it does not exist.
`static byte[]`	`readFileToByteArray(File file)` Reads the contents of a file into a byte array.
`static String`	`readFileToString(File file)` Deprecated. 2.5 use `readFileToString(File, Charset)` instead
`static String`	`readFileToString(File file, Charset encoding)` Reads the contents of a file into a String.
`static String`	`readFileToString(File file, String encoding)` Reads the contents of a file into a String.
`static List<String>`	`readLines(File file)` Deprecated. 2.5 use `readLines(File, Charset)` instead
`static List<String>`	`readLines(File file, Charset encoding)` Reads the contents of a file line by line to a List of Strings.
`static List<String>`	`readLines(File file, String encoding)` Reads the contents of a file line by line to a List of Strings.
`static long`	`sizeOf(File file)` Returns the size of the specified file or directory.
`static BigInteger`	`sizeOfAsBigInteger(File file)` Returns the size of the specified file or directory.
`static long`	`sizeOfDirectory(File directory)` Counts the size of a directory recursively (sum of the length of all files).
`static BigInteger`	`sizeOfDirectoryAsBigInteger(File directory)` Counts the size of a directory recursively (sum of the length of all files).
`static File`	`toFile(URL url)` Convert from a `URL` to a `File`.
`static File[]`	`toFiles(URL[] urls)` Converts each of an array of `URL` to a `File`.
`static void`	`touch(File file)` Implements the same behaviour as the "touch" utility on Unix.
`static URL[]`	`toURLs(File[] files)` Converts each of an array of `File` to a `URL`.
`static boolean`	`waitFor(File file, int seconds)` Waits for NFS to propagate a file creation, imposing a timeout.
`static void`	`write(File file, CharSequence data)` Deprecated. 2.5 use `write(File, CharSequence, Charset)` instead
`static void`	`write(File file, CharSequence data, boolean append)` Deprecated. 2.5 use `write(File, CharSequence, Charset, boolean)` instead
`static void`	`write(File file, CharSequence data, Charset encoding)` Writes a CharSequence to a file creating the file if it does not exist.
`static void`	`write(File file, CharSequence data, Charset encoding, boolean append)` Writes a CharSequence to a file creating the file if it does not exist.
`static void`	`write(File file, CharSequence data, String encoding)` Writes a CharSequence to a file creating the file if it does not exist.
`static void`	`write(File file, CharSequence data, String encoding, boolean append)` Writes a CharSequence to a file creating the file if it does not exist.
`static void`	`writeByteArrayToFile(File file, byte[] data)` Writes a byte array to a file creating the file if it does not exist.
`static void`	`writeByteArrayToFile(File file, byte[] data, boolean append)` Writes a byte array to a file creating the file if it does not exist.
`static void`	`writeByteArrayToFile(File file, byte[] data, int off, int len)` Writes `len` bytes from the specified byte array starting at offset `off` to a file, creating the file if it does not exist.
`static void`	`writeByteArrayToFile(File file, byte[] data, int off, int len, boolean append)` Writes `len` bytes from the specified byte array starting at offset `off` to a file, creating the file if it does not exist.
`static void`	`writeLines(File file, Collection<?> lines)` Writes the `toString()` value of each item in a collection to the specified `File` line by line.
`static void`	`writeLines(File file, Collection<?> lines, boolean append)` Writes the `toString()` value of each item in a collection to the specified `File` line by line.
`static void`	`writeLines(File file, Collection<?> lines, String lineEnding)` Writes the `toString()` value of each item in a collection to the specified `File` line by line.
`static void`	`writeLines(File file, Collection<?> lines, String lineEnding, boolean append)` Writes the `toString()` value of each item in a collection to the specified `File` line by line.
`static void`	`writeLines(File file, String encoding, Collection<?> lines)` Writes the `toString()` value of each item in a collection to the specified `File` line by line.
`static void`	`writeLines(File file, String encoding, Collection<?> lines, boolean append)` Writes the `toString()` value of each item in a collection to the specified `File` line by line, optionally appending.
`static void`	`writeLines(File file, String encoding, Collection<?> lines, String lineEnding)` Writes the `toString()` value of each item in a collection to the specified `File` line by line.
`static void`	`writeLines(File file, String encoding, Collection<?> lines, String lineEnding, boolean append)` Writes the `toString()` value of each item in a collection to the specified `File` line by line.
`static void`	`writeStringToFile(File file, String data)` Deprecated. 2.5 use `writeStringToFile(File, String, Charset)` instead
`static void`	`writeStringToFile(File file, String data, boolean append)` Deprecated. 2.5 use `writeStringToFile(File, String, Charset, boolean)` instead
`static void`	`writeStringToFile(File file, String data, Charset encoding)` Writes a String to a file creating the file if it does not exist.
`static void`	`writeStringToFile(File file, String data, Charset encoding, boolean append)` Writes a String to a file creating the file if it does not exist.
`static void`	`writeStringToFile(File file, String data, String encoding)` Writes a String to a file creating the file if it does not exist.
`static void`	`writeStringToFile(File file, String data, String encoding, boolean append)` Writes a String to a file creating the file if it does not exist.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - ONE_KB
```
public static final long ONE_KB
```
    The number of bytes in a kilobyte.
    
    See Also:
    Constant Field Values
  - ONE_KB_BI
```
public static final BigInteger ONE_KB_BI
```
    The number of bytes in a kilobyte.
    
    Since:
    
    2.4
  - ONE_MB
```
public static final long ONE_MB
```
    The number of bytes in a megabyte.
    
    See Also:
    Constant Field Values
  - ONE_MB_BI
```
public static final BigInteger ONE_MB_BI
```
    The number of bytes in a megabyte.
    
    Since:
    
    2.4
  - ONE_GB
```
public static final long ONE_GB
```
    The number of bytes in a gigabyte.
    
    See Also:
    Constant Field Values
  - ONE_GB_BI
```
public static final BigInteger ONE_GB_BI
```
    The number of bytes in a gigabyte.
    
    Since:
    
    2.4
  - ONE_TB
```
public static final long ONE_TB
```
    The number of bytes in a terabyte.
    
    See Also:
    Constant Field Values
  - ONE_TB_BI
```
public static final BigInteger ONE_TB_BI
```
    The number of bytes in a terabyte.
    
    Since:
    
    2.4
  - ONE_PB
```
public static final long ONE_PB
```
    The number of bytes in a petabyte.
    
    See Also:
    Constant Field Values
  - ONE_PB_BI
```
public static final BigInteger ONE_PB_BI
```
    The number of bytes in a petabyte.
    
    Since:
    
    2.4
  - ONE_EB
```
public static final long ONE_EB
```
    The number of bytes in an exabyte.
    
    See Also:
    Constant Field Values
  - ONE_EB_BI
```
public static final BigInteger ONE_EB_BI
```
    The number of bytes in an exabyte.
    
    Since:
    
    2.4
  - ONE_ZB
```
public static final BigInteger ONE_ZB
```
    The number of bytes in a zettabyte.
  - ONE_YB
```
public static final BigInteger ONE_YB
```
    The number of bytes in a yottabyte.
  - EMPTY_FILE_ARRAY
```
public static final File[] EMPTY_FILE_ARRAY
```
    An empty array of type File.
- Constructor Detail
  - FileUtils
```
public FileUtils()
```
    Instances should NOT be constructed in standard programming.
- Method Detail
  - getFile
```
public static File getFile(File directory,
           String... names)
```
    Construct a file from the set of name elements.
    
    Parameters:
    directory - the parent directory
    names - the name elements
    
    Returns:
    the file
    Since:
    
    2.1
  - getFile
```
public static File getFile(String... names)
```
    Construct a file from the set of name elements.
    
    Parameters:
    names - the name elements
    
    Returns:
    the file
    Since:
    
    2.1
  - getTempDirectoryPath
```
public static String getTempDirectoryPath()
```
    Returns the path to the system temporary directory.
    
    Returns:
    the path to the system temporary directory.
    Since:
    
    2.0
  - getTempDirectory
```
public static File getTempDirectory()
```
    Returns a File representing the system temporary directory.
    
    Returns:
    the system temporary directory.
    Since:
    
    2.0
  - getUserDirectoryPath
```
public static String getUserDirectoryPath()
```
    Returns the path to the user's home directory.
    
    Returns:
    the path to the user's home directory.
    Since:
    
    2.0
  - getUserDirectory
```
public static File getUserDirectory()
```
    Returns a File representing the user's home directory.
    
    Returns:
    the user's home directory.
    Since:
    
    2.0
  - openInputStream
```
public static FileInputStream openInputStream(File file)
                                       throws IOException
```
    Opens a FileInputStream for the specified file, providing better error messages than simply calling new FileInputStream(file).
    At the end of the method either the stream will be successfully opened, or an exception will have been thrown.
    An exception is thrown if the file does not exist. An exception is thrown if the file object exists but is a directory. An exception is thrown if the file exists but cannot be read.
    
    Parameters:
    file - the file to open for input, must not be null
    
    Returns:
    a new FileInputStream for the specified file
    
    Throws:
    
    FileNotFoundException - if the file does not exist
    
    IOException - if the file object is a directory
    
    IOException - if the file cannot be read
    Since:
    
    1.3
  - openOutputStream
```
public static FileOutputStream openOutputStream(File file)
                                         throws IOException
```
    Opens a FileOutputStream for the specified file, checking and creating the parent directory if it does not exist.
    At the end of the method either the stream will be successfully opened, or an exception will have been thrown.
    The parent directory will be created if it does not exist. The file will be created if it does not exist. An exception is thrown if the file object exists but is a directory. An exception is thrown if the file exists but cannot be written to. An exception is thrown if the parent directory cannot be created.
    
    Parameters:
    file - the file to open for output, must not be null
    
    Returns:
    a new FileOutputStream for the specified file
    
    Throws:
    
    IOException - if the file object is a directory
    
    IOException - if the file cannot be written to
    
    IOException - if a parent directory needs creating but that fails
    Since:
    
    1.3
  - openOutputStream
```
public static FileOutputStream openOutputStream(File file,
                                boolean append)
                                         throws IOException
```
    Opens a FileOutputStream for the specified file, checking and creating the parent directory if it does not exist.
    At the end of the method either the stream will be successfully opened, or an exception will have been thrown.
    The parent directory will be created if it does not exist. The file will be created if it does not exist. An exception is thrown if the file object exists but is a directory. An exception is thrown if the file exists but cannot be written to. An exception is thrown if the parent directory cannot be created.
    
    Parameters:
    file - the file to open for output, must not be null
    append - if true, then bytes will be added to the end of the file rather than overwriting
    
    Returns:
    a new FileOutputStream for the specified file
    
    Throws:
    
    IOException - if the file object is a directory
    
    IOException - if the file cannot be written to
    
    IOException - if a parent directory needs creating but that fails
    Since:
    
    2.1
  - byteCountToDisplaySize
```
public static String byteCountToDisplaySize(BigInteger size)
```
    Returns a human-readable version of the file size, where the input represents a specific number of bytes.
    If the size is over 1GB, the size is returned as the number of whole GB, i.e. the size is rounded down to the nearest GB boundary.
    
    Similarly for the 1MB and 1KB boundaries.
    
    Parameters:
    size - the number of bytes
    
    Returns:
    a human-readable display value (includes units - EB, PB, TB, GB, MB, KB or bytes)
    Since:
    
    2.4
    
    See Also:
    IO-226 - should the rounding be changed?
  - byteCountToDisplaySize
```
public static String byteCountToDisplaySize(long size)
```
    Returns a human-readable version of the file size, where the input represents a specific number of bytes.
    If the size is over 1GB, the size is returned as the number of whole GB, i.e. the size is rounded down to the nearest GB boundary.
    
    Similarly for the 1MB and 1KB boundaries.
    
    Parameters:
    size - the number of bytes
    
    Returns:
    a human-readable display value (includes units - EB, PB, TB, GB, MB, KB or bytes)
    See Also:
    IO-226 - should the rounding be changed?
  - touch
```
public static void touch(File file)
                  throws IOException
```
    Implements the same behaviour as the "touch" utility on Unix. It creates a new file with size 0 or, if the file exists already, it is opened and closed without modifying it, but updating the file date and time.
    NOTE: As from v1.3, this method throws an IOException if the last modified date of the file cannot be set. Also, as from v1.3 this method creates parent directories if they do not exist.
    
    Parameters:
    file - the File to touch
    
    Throws:
    
    IOException - If an I/O problem occurs
  - convertFileCollectionToFileArray
```
public static File[] convertFileCollectionToFileArray(Collection<File> files)
```
    Converts a Collection containing java.io.File instanced into array representation. This is to account for the difference between File.listFiles() and FileUtils.listFiles().
    
    Parameters:
    files - a Collection containing java.io.File instances
    
    Returns:
    an array of java.io.File
  - listFiles
```
public static Collection<File> listFiles(File directory,
                         IOFileFilter fileFilter,
                         IOFileFilter dirFilter)
```
    Finds files within a given directory (and optionally its subdirectories). All files found are filtered by an IOFileFilter.
    If your search should recurse into subdirectories you can pass in an IOFileFilter for directories. You don't need to bind a DirectoryFileFilter (via logical AND) to this filter. This method does that for you.
    An example: If you want to search through all directories called "temp" you pass in FileFilterUtils.NameFileFilter("temp")
    Another common usage of this method is find files in a directory tree but ignoring the directories generated CVS. You can simply pass in FileFilterUtils.makeCVSAware(null).
    
    Parameters:
    directory - the directory to search in
    fileFilter - filter to apply when finding files.
    dirFilter - optional filter to apply when finding subdirectories. If this parameter is null, subdirectories will not be included in the search. Use TrueFileFilter.INSTANCE to match all directories.
    
    Returns:
    an collection of java.io.File with the matching files
    See Also:
    FileFilterUtils, NameFileFilter
  - listFilesAndDirs
```
public static Collection<File> listFilesAndDirs(File directory,
                                IOFileFilter fileFilter,
                                IOFileFilter dirFilter)
```
    Finds files within a given directory (and optionally its subdirectories). All files found are filtered by an IOFileFilter.
    The resulting collection includes the starting directory and any subdirectories that match the directory filter.
    
    Parameters:
    directory - the directory to search in
    fileFilter - filter to apply when finding files.
    dirFilter - optional filter to apply when finding subdirectories. If this parameter is null, subdirectories will not be included in the search. Use TrueFileFilter.INSTANCE to match all directories.
    
    Returns:
    an collection of java.io.File with the matching files
    Since:
    
    2.2
    
    See Also:
    listFiles(java.io.File, org.apache.commons.io.filefilter.IOFileFilter, org.apache.commons.io.filefilter.IOFileFilter), FileFilterUtils, NameFileFilter
  - iterateFiles
```
public static Iterator<File> iterateFiles(File directory,
                          IOFileFilter fileFilter,
                          IOFileFilter dirFilter)
```
    Allows iteration over the files in given directory (and optionally its subdirectories).
    All files found are filtered by an IOFileFilter. This method is based on listFiles(File, IOFileFilter, IOFileFilter), which supports Iterable ('foreach' loop).
    
    Parameters:
    directory - the directory to search in
    fileFilter - filter to apply when finding files.
    dirFilter - optional filter to apply when finding subdirectories. If this parameter is null, subdirectories will not be included in the search. Use TrueFileFilter.INSTANCE to match all directories.
    
    Returns:
    an iterator of java.io.File for the matching files
    Since:
    
    1.2
    
    See Also:
    FileFilterUtils, NameFileFilter
  - iterateFilesAndDirs
```
public static Iterator<File> iterateFilesAndDirs(File directory,
                                 IOFileFilter fileFilter,
                                 IOFileFilter dirFilter)
```
    Allows iteration over the files in given directory (and optionally its subdirectories).
    All files found are filtered by an IOFileFilter. This method is based on listFilesAndDirs(File, IOFileFilter, IOFileFilter), which supports Iterable ('foreach' loop).
    The resulting iterator includes the subdirectories themselves.
    
    Parameters:
    directory - the directory to search in
    fileFilter - filter to apply when finding files.
    dirFilter - optional filter to apply when finding subdirectories. If this parameter is null, subdirectories will not be included in the search. Use TrueFileFilter.INSTANCE to match all directories.
    
    Returns:
    an iterator of java.io.File for the matching files
    Since:
    
    2.2
    
    See Also:
    FileFilterUtils, NameFileFilter
  - listFiles
```
public static Collection<File> listFiles(File directory,
                         String[] extensions,
                         boolean recursive)
```
    Finds files within a given directory (and optionally its subdirectories) which match an array of extensions.
    
    Parameters:
    directory - the directory to search in
    extensions - an array of extensions, ex. {"java","xml"}. If this parameter is null, all files are returned.
    recursive - if true all subdirectories are searched as well
    
    Returns:
    an collection of java.io.File with the matching files
  - iterateFiles
```
public static Iterator<File> iterateFiles(File directory,
                          String[] extensions,
                          boolean recursive)
```
    Allows iteration over the files in a given directory (and optionally its subdirectories) which match an array of extensions. This method is based on listFiles(File, String[], boolean), which supports Iterable ('foreach' loop).
    
    Parameters:
    directory - the directory to search in
    extensions - an array of extensions, ex. {"java","xml"}. If this parameter is null, all files are returned.
    recursive - if true all subdirectories are searched as well
    
    Returns:
    an iterator of java.io.File with the matching files
    Since:
    
    1.2
  - contentEquals
```
public static boolean contentEquals(File file1,
                    File file2)
                             throws IOException
```
    Compares the contents of two files to determine if they are equal or not.
    This method checks to see if the two files are different lengths or if they point to the same file, before resorting to byte-by-byte comparison of the contents.
    Code origin: Avalon
    
    Parameters:
    file1 - the first file
    file2 - the second file
    
    Returns:
    true if the content of the files are equal or they both don't exist, false otherwise
    
    Throws:
    
    IOException - in case of an I/O error
  - contentEqualsIgnoreEOL
```
public static boolean contentEqualsIgnoreEOL(File file1,
                             File file2,
                             String charsetName)
                                      throws IOException
```
    Compares the contents of two files to determine if they are equal or not.
    This method checks to see if the two files point to the same file, before resorting to line-by-line comparison of the contents.
    
    Parameters:
    file1 - the first file
    file2 - the second file
    charsetName - the character encoding to be used. May be null, in which case the platform default is used
    
    Returns:
    true if the content of the files are equal or neither exists, false otherwise
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    2.2
    
    See Also:
    IOUtils.contentEqualsIgnoreEOL(Reader, Reader)
  - toFile
```
public static File toFile(URL url)
```
    Convert from a URL to a File.
    From version 1.1 this method will decode the URL. Syntax such as file:///my%20docs/file.txt will be correctly decoded to /my docs/file.txt. Starting with version 1.5, this method uses UTF-8 to decode percent-encoded octets to characters. Additionally, malformed percent-encoded octets are handled leniently by passing them through literally.
    
    Parameters:
    url - the file URL to convert, null returns null
    
    Returns:
    the equivalent File object, or null if the URL's protocol is not file
  - toFiles
```
public static File[] toFiles(URL[] urls)
```
    Converts each of an array of URL to a File.
    Returns an array of the same size as the input. If the input is null, an empty array is returned. If the input contains null, the output array contains null at the same index.
    This method will decode the URL. Syntax such as file:///my%20docs/file.txt will be correctly decoded to /my docs/file.txt.
    
    Parameters:
    urls - the file URLs to convert, null returns empty array
    
    Returns:
    a non-null array of Files matching the input, with a null item if there was a null at that index in the input array
    
    Throws:
    
    IllegalArgumentException - if any file is not a URL file
    
    IllegalArgumentException - if any file is incorrectly encoded
    Since:
    
    1.1
  - toURLs
```
public static URL[] toURLs(File[] files)
                    throws IOException
```
    Converts each of an array of File to a URL.
    Returns an array of the same size as the input.
    
    Parameters:
    files - the files to convert, must not be null
    
    Returns:
    an array of URLs matching the input
    
    Throws:
    
    IOException - if a file cannot be converted
    
    NullPointerException - if the parameter is null
  - copyFileToDirectory
```
public static void copyFileToDirectory(File srcFile,
                       File destDir)
                                throws IOException
```
    Copies a file to a directory preserving the file date.
    This method copies the contents of the specified source file to a file of the same name in the specified destination directory. The destination directory is created if it does not exist. If the destination file exists, then this method will overwrite it.
    Note: This method tries to preserve the file's last modified date/times using File.setLastModified(long), however it is not guaranteed that the operation will succeed. If the modification operation fails, no indication is provided.
    
    Parameters:
    srcFile - an existing file to copy, must not be null
    destDir - the directory to place the copy in, must not be null
    
    Throws:
    
    NullPointerException - if source or destination is null
    
    IOException - if source or destination is invalid
    
    IOException - if an IO error occurs during copying
    See Also:
    copyFile(File, File, boolean)
  - copyFileToDirectory
```
public static void copyFileToDirectory(File srcFile,
                       File destDir,
                       boolean preserveFileDate)
                                throws IOException
```
    Copies a file to a directory optionally preserving the file date.
    This method copies the contents of the specified source file to a file of the same name in the specified destination directory. The destination directory is created if it does not exist. If the destination file exists, then this method will overwrite it.
    Note: Setting preserveFileDate to true tries to preserve the file's last modified date/times using File.setLastModified(long), however it is not guaranteed that the operation will succeed. If the modification operation fails, no indication is provided.
    
    Parameters:
    srcFile - an existing file to copy, must not be null
    destDir - the directory to place the copy in, must not be null
    preserveFileDate - true if the file date of the copy should be the same as the original
    
    Throws:
    
    NullPointerException - if source or destination is null
    
    IOException - if source or destination is invalid
    
    IOException - if an IO error occurs during copying
    
    IOException - if the output file length is not the same as the input file length after the copy completes
    Since:
    
    1.3
    
    See Also:
    copyFile(File, File, boolean)
  - copyFile
```
public static void copyFile(File srcFile,
            File destFile)
                     throws IOException
```
    Copies a file to a new location preserving the file date.
    This method copies the contents of the specified source file to the specified destination file. The directory holding the destination file is created if it does not exist. If the destination file exists, then this method will overwrite it.
    Note: This method tries to preserve the file's last modified date/times using File.setLastModified(long), however it is not guaranteed that the operation will succeed. If the modification operation fails, no indication is provided.
    
    Parameters:
    srcFile - an existing file to copy, must not be null
    destFile - the new file, must not be null
    
    Throws:
    
    NullPointerException - if source or destination is null
    
    IOException - if source or destination is invalid
    
    IOException - if an IO error occurs during copying
    
    IOException - if the output file length is not the same as the input file length after the copy completes
    See Also:
    copyFileToDirectory(File, File), copyFile(File, File, boolean)
  - copyFile
```
public static void copyFile(File srcFile,
            File destFile,
            boolean preserveFileDate)
                     throws IOException
```
    Copies a file to a new location.
    This method copies the contents of the specified source file to the specified destination file. The directory holding the destination file is created if it does not exist. If the destination file exists, then this method will overwrite it.
    Note: Setting preserveFileDate to true tries to preserve the file's last modified date/times using File.setLastModified(long), however it is not guaranteed that the operation will succeed. If the modification operation fails, no indication is provided.
    
    Parameters:
    srcFile - an existing file to copy, must not be null
    destFile - the new file, must not be null
    preserveFileDate - true if the file date of the copy should be the same as the original
    
    Throws:
    
    NullPointerException - if source or destination is null
    
    IOException - if source or destination is invalid
    
    IOException - if an IO error occurs during copying
    
    IOException - if the output file length is not the same as the input file length after the copy completes
    See Also:
    copyFileToDirectory(File, File, boolean), doCopyFile(File, File, boolean)
  - copyFile
```
public static long copyFile(File input,
            OutputStream output)
                     throws IOException
```
    Copy bytes from a File to an OutputStream.
    This method buffers the input internally, so there is no need to use a BufferedInputStream.
    
    Parameters:
    input - the File to read from
    output - the OutputStream to write to
    
    Returns:
    the number of bytes copied
    
    Throws:
    
    NullPointerException - if the input or output is null
    
    IOException - if an I/O error occurs
    Since:
    
    2.1
  - copyDirectoryToDirectory
```
public static void copyDirectoryToDirectory(File srcDir,
                            File destDir)
                                     throws IOException
```
    Copies a directory to within another directory preserving the file dates.
    This method copies the source directory and all its contents to a directory of the same name in the specified destination directory.
    The destination directory is created if it does not exist. If the destination directory did exist, then this method merges the source with the destination, with the source taking precedence.
    Note: This method tries to preserve the files' last modified date/times using File.setLastModified(long), however it is not guaranteed that those operations will succeed. If the modification operation fails, no indication is provided.
    
    Parameters:
    srcDir - an existing directory to copy, must not be null
    destDir - the directory to place the copy in, must not be null
    
    Throws:
    
    NullPointerException - if source or destination is null
    
    IOException - if source or destination is invalid
    
    IOException - if an IO error occurs during copying
    Since:
    
    1.2
  - copyDirectory
```
public static void copyDirectory(File srcDir,
                 File destDir)
                          throws IOException
```
    Copies a whole directory to a new location preserving the file dates.
    This method copies the specified directory and all its child directories and files to the specified destination. The destination is the new location and name of the directory.
    The destination directory is created if it does not exist. If the destination directory did exist, then this method merges the source with the destination, with the source taking precedence.
    Note: This method tries to preserve the files' last modified date/times using File.setLastModified(long), however it is not guaranteed that those operations will succeed. If the modification operation fails, no indication is provided.
    
    Parameters:
    srcDir - an existing directory to copy, must not be null
    destDir - the new directory, must not be null
    
    Throws:
    
    NullPointerException - if source or destination is null
    
    IOException - if source or destination is invalid
    
    IOException - if an IO error occurs during copying
    Since:
    
    1.1
  - copyDirectory
```
public static void copyDirectory(File srcDir,
                 File destDir,
                 boolean preserveFileDate)
                          throws IOException
```
    Copies a whole directory to a new location.
    This method copies the contents of the specified source directory to within the specified destination directory.
    The destination directory is created if it does not exist. If the destination directory did exist, then this method merges the source with the destination, with the source taking precedence.
    Note: Setting preserveFileDate to true tries to preserve the files' last modified date/times using File.setLastModified(long), however it is not guaranteed that those operations will succeed. If the modification operation fails, no indication is provided.
    
    Parameters:
    srcDir - an existing directory to copy, must not be null
    destDir - the new directory, must not be null
    preserveFileDate - true if the file date of the copy should be the same as the original
    
    Throws:
    
    NullPointerException - if source or destination is null
    
    IOException - if source or destination is invalid
    
    IOException - if an IO error occurs during copying
    Since:
    
    1.1
  - copyDirectory
```
public static void copyDirectory(File srcDir,
                 File destDir,
                 FileFilter filter)
                          throws IOException
```
    Copies a filtered directory to a new location preserving the file dates.
    This method copies the contents of the specified source directory to within the specified destination directory.
    The destination directory is created if it does not exist. If the destination directory did exist, then this method merges the source with the destination, with the source taking precedence.
    Note: This method tries to preserve the files' last modified date/times using File.setLastModified(long), however it is not guaranteed that those operations will succeed. If the modification operation fails, no indication is provided.
    
    Example: Copy directories only
```
  // only copy the directory structure
  FileUtils.copyDirectory(srcDir, destDir, DirectoryFileFilter.DIRECTORY);
  
```
    Example: Copy directories and txt files
```
  // Create a filter for ".txt" files
  IOFileFilter txtSuffixFilter = FileFilterUtils.suffixFileFilter(".txt");
  IOFileFilter txtFiles = FileFilterUtils.andFileFilter(FileFileFilter.FILE, txtSuffixFilter);

  // Create a filter for either directories or ".txt" files
  FileFilter filter = FileFilterUtils.orFileFilter(DirectoryFileFilter.DIRECTORY, txtFiles);

  // Copy using the filter
  FileUtils.copyDirectory(srcDir, destDir, filter);
  
```
    Parameters:
    srcDir - an existing directory to copy, must not be null
    destDir - the new directory, must not be null
    filter - the filter to apply, null means copy all directories and files should be the same as the original
    
    Throws:
    
    NullPointerException - if source or destination is null
    
    IOException - if source or destination is invalid
    
    IOException - if an IO error occurs during copying
    Since:
    
    1.4
  - copyDirectory
```
public static void copyDirectory(File srcDir,
                 File destDir,
                 FileFilter filter,
                 boolean preserveFileDate)
                          throws IOException
```
    Copies a filtered directory to a new location.
    This method copies the contents of the specified source directory to within the specified destination directory.
    The destination directory is created if it does not exist. If the destination directory did exist, then this method merges the source with the destination, with the source taking precedence.
    Note: Setting preserveFileDate to true tries to preserve the files' last modified date/times using File.setLastModified(long), however it is not guaranteed that those operations will succeed. If the modification operation fails, no indication is provided.
    
    Example: Copy directories only
```
  // only copy the directory structure
  FileUtils.copyDirectory(srcDir, destDir, DirectoryFileFilter.DIRECTORY, false);
  
```
    Example: Copy directories and txt files
```
  // Create a filter for ".txt" files
  IOFileFilter txtSuffixFilter = FileFilterUtils.suffixFileFilter(".txt");
  IOFileFilter txtFiles = FileFilterUtils.andFileFilter(FileFileFilter.FILE, txtSuffixFilter);

  // Create a filter for either directories or ".txt" files
  FileFilter filter = FileFilterUtils.orFileFilter(DirectoryFileFilter.DIRECTORY, txtFiles);

  // Copy using the filter
  FileUtils.copyDirectory(srcDir, destDir, filter, false);
  
```
    Parameters:
    srcDir - an existing directory to copy, must not be null
    destDir - the new directory, must not be null
    filter - the filter to apply, null means copy all directories and files
    preserveFileDate - true if the file date of the copy should be the same as the original
    
    Throws:
    
    NullPointerException - if source or destination is null
    
    IOException - if source or destination is invalid
    
    IOException - if an IO error occurs during copying
    Since:
    
    1.4
  - copyURLToFile
```
public static void copyURLToFile(URL source,
                 File destination)
                          throws IOException
```
    Copies bytes from the URL source to a file destination. The directories up to destination will be created if they don't already exist. destination will be overwritten if it already exists.
    Warning: this method does not set a connection or read timeout and thus might block forever. Use copyURLToFile(URL, File, int, int) with reasonable timeouts to prevent this.
    
    Parameters:
    source - the URL to copy bytes from, must not be null
    destination - the non-directory File to write bytes to (possibly overwriting), must not be null
    
    Throws:
    
    IOException - if source URL cannot be opened
    
    IOException - if destination is a directory
    
    IOException - if destination cannot be written
    
    IOException - if destination needs creating but can't be
    
    IOException - if an IO error occurs during copying
  - copyURLToFile
```
public static void copyURLToFile(URL source,
                 File destination,
                 int connectionTimeout,
                 int readTimeout)
                          throws IOException
```
    Copies bytes from the URL source to a file destination. The directories up to destination will be created if they don't already exist. destination will be overwritten if it already exists.
    
    Parameters:
    source - the URL to copy bytes from, must not be null
    destination - the non-directory File to write bytes to (possibly overwriting), must not be null
    connectionTimeout - the number of milliseconds until this method will timeout if no connection could be established to the source
    readTimeout - the number of milliseconds until this method will timeout if no data could be read from the source
    
    Throws:
    
    IOException - if source URL cannot be opened
    
    IOException - if destination is a directory
    
    IOException - if destination cannot be written
    
    IOException - if destination needs creating but can't be
    
    IOException - if an IO error occurs during copying
    Since:
    
    2.0
  - copyInputStreamToFile
```
public static void copyInputStreamToFile(InputStream source,
                         File destination)
                                  throws IOException
```
    Copies bytes from an InputStream source to a file destination. The directories up to destination will be created if they don't already exist. destination will be overwritten if it already exists. The source stream is closed. See copyToFile(InputStream, File) for a method that does not close the input stream.
    
    Parameters:
    source - the InputStream to copy bytes from, must not be null, will be closed
    destination - the non-directory File to write bytes to (possibly overwriting), must not be null
    
    Throws:
    
    IOException - if destination is a directory
    
    IOException - if destination cannot be written
    
    IOException - if destination needs creating but can't be
    
    IOException - if an IO error occurs during copying
    Since:
    
    2.0
  - copyToFile
```
public static void copyToFile(InputStream source,
              File destination)
                       throws IOException
```
    Copies bytes from an InputStream source to a file destination. The directories up to destination will be created if they don't already exist. destination will be overwritten if it already exists. The source stream is left open, e.g. for use with ZipInputStream. See copyInputStreamToFile(InputStream, File) for a method that closes the input stream.
    
    Parameters:
    source - the InputStream to copy bytes from, must not be null
    destination - the non-directory File to write bytes to (possibly overwriting), must not be null
    
    Throws:
    
    IOException - if destination is a directory
    
    IOException - if destination cannot be written
    
    IOException - if destination needs creating but can't be
    
    IOException - if an IO error occurs during copying
    Since:
    
    2.5
  - deleteDirectory
```
public static void deleteDirectory(File directory)
                            throws IOException
```
    Deletes a directory recursively.
    
    Parameters:
    directory - directory to delete
    
    Throws:
    
    IOException - in case deletion is unsuccessful
    
    IllegalArgumentException - if directory does not exist or is not a directory
  - deleteQuietly
```
public static boolean deleteQuietly(File file)
```
    Deletes a file, never throwing an exception. If file is a directory, delete it and all sub-directories.
    The difference between File.delete() and this method are:
    - A directory to be deleted does not have to be empty.
    - No exceptions are thrown when a file or directory cannot be deleted.
    Parameters:
    file - file or directory to delete, can be null
    
    Returns:
    true if the file or directory was deleted, otherwise false
    Since:
    
    1.4
  - directoryContains
```
public static boolean directoryContains(File directory,
                        File child)
                                 throws IOException
```
    Determines whether the parent directory contains the child element (a file or directory).
    Files are normalized before comparison.
    Edge cases:
    - A directory must not be null: if null, throw IllegalArgumentException
    - A directory must be a directory: if not a directory, throw IllegalArgumentException
    - A directory does not contain itself: return false
    - A null child file is not contained in any parent: return false
    Parameters:
    directory - the file to consider as the parent.
    child - the file to consider as the child.
    
    Returns:
    true is the candidate leaf is under by the specified composite. False otherwise.
    
    Throws:
    
    IOException - if an IO error occurs while checking the files.
    
    IllegalArgumentException - if directory is null or not a directory.
    Since:
    
    2.2
    
    See Also:
    FilenameUtils.directoryContains(String, String)
  - cleanDirectory
```
public static void cleanDirectory(File directory)
                           throws IOException
```
    Cleans a directory without deleting it.
    
    Parameters:
    directory - directory to clean
    
    Throws:
    
    IOException - in case cleaning is unsuccessful
    
    IllegalArgumentException - if directory does not exist or is not a directory
  - waitFor
```
public static boolean waitFor(File file,
              int seconds)
```
    Waits for NFS to propagate a file creation, imposing a timeout.
    This method repeatedly tests File.exists() until it returns true up to the maximum time specified in seconds.
    
    Parameters:
    file - the file to check, must not be null
    seconds - the maximum time in seconds to wait
    
    Returns:
    true if file exists
    
    Throws:
    
    NullPointerException - if the file is null
  - readFileToString
```
public static String readFileToString(File file,
                      Charset encoding)
                               throws IOException
```
    Reads the contents of a file into a String. The file is always closed.
    
    Parameters:
    file - the file to read, must not be null
    encoding - the encoding to use, null means platform default
    
    Returns:
    the file contents, never null
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    2.3
  - readFileToString
```
public static String readFileToString(File file,
                      String encoding)
                               throws IOException
```
    Reads the contents of a file into a String. The file is always closed.
    
    Parameters:
    file - the file to read, must not be null
    encoding - the encoding to use, null means platform default
    
    Returns:
    the file contents, never null
    
    Throws:
    
    IOException - in case of an I/O error
    
    UnsupportedCharsetException - thrown instead of .UnsupportedEncodingException in version 2.2 if the encoding is not supported.
    Since:
    
    2.3
  - readFileToString
```
@Deprecated
public static String readFileToString(File file)
                               throws IOException
```
    Deprecated. 2.5 use readFileToString(File, Charset) instead
    
    Reads the contents of a file into a String using the default encoding for the VM. The file is always closed.
    
    Parameters:
    file - the file to read, must not be null
    
    Returns:
    the file contents, never null
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    1.3.1
  - readFileToByteArray
```
public static byte[] readFileToByteArray(File file)
                                  throws IOException
```
    Reads the contents of a file into a byte array. The file is always closed.
    
    Parameters:
    file - the file to read, must not be null
    
    Returns:
    the file contents, never null
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    1.1
  - readLines
```
public static List<String> readLines(File file,
                     Charset encoding)
                              throws IOException
```
    Reads the contents of a file line by line to a List of Strings. The file is always closed.
    
    Parameters:
    file - the file to read, must not be null
    encoding - the encoding to use, null means platform default
    
    Returns:
    the list of Strings representing each line in the file, never null
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    2.3
  - readLines
```
public static List<String> readLines(File file,
                     String encoding)
                              throws IOException
```
    Reads the contents of a file line by line to a List of Strings. The file is always closed.
    
    Parameters:
    file - the file to read, must not be null
    encoding - the encoding to use, null means platform default
    
    Returns:
    the list of Strings representing each line in the file, never null
    
    Throws:
    
    IOException - in case of an I/O error
    
    UnsupportedCharsetException - thrown instead of .UnsupportedEncodingException in version 2.2 if the encoding is not supported.
    Since:
    
    1.1
  - readLines
```
@Deprecated
public static List<String> readLines(File file)
                              throws IOException
```
    Deprecated. 2.5 use readLines(File, Charset) instead
    
    Reads the contents of a file line by line to a List of Strings using the default encoding for the VM. The file is always closed.
    
    Parameters:
    file - the file to read, must not be null
    
    Returns:
    the list of Strings representing each line in the file, never null
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    1.3
  - lineIterator
```
public static LineIterator lineIterator(File file,
                        String encoding)
                                 throws IOException
```
    Returns an Iterator for the lines in a File.
    This method opens an InputStream for the file. When you have finished with the iterator you should close the stream to free internal resources. This can be done by calling the LineIterator.close() or LineIterator.closeQuietly(LineIterator) method.
    The recommended usage pattern is:
```
 LineIterator it = FileUtils.lineIterator(file, "UTF-8");
 try {
   while (it.hasNext()) {
     String line = it.nextLine();
     /// do something with line
   }
 } finally {
   LineIterator.closeQuietly(iterator);
 }
 
```
    If an exception occurs during the creation of the iterator, the underlying stream is closed.
    Parameters:
    file - the file to open for input, must not be null
    encoding - the encoding to use, null means platform default
    
    Returns:
    an Iterator of the lines in the file, never null
    
    Throws:
    
    IOException - in case of an I/O error (file closed)
    Since:
    
    1.2
  - lineIterator
```
public static LineIterator lineIterator(File file)
                                 throws IOException
```
    Returns an Iterator for the lines in a File using the default encoding for the VM.
    
    Parameters:
    file - the file to open for input, must not be null
    
    Returns:
    an Iterator of the lines in the file, never null
    
    Throws:
    
    IOException - in case of an I/O error (file closed)
    Since:
    
    1.3
    
    See Also:
    lineIterator(File, String)
  - writeStringToFile
```
public static void writeStringToFile(File file,
                     String data,
                     Charset encoding)
                              throws IOException
```
    Writes a String to a file creating the file if it does not exist.
    NOTE: As from v1.3, the parent directories of the file will be created if they do not exist.
    
    Parameters:
    file - the file to write
    data - the content to write to the file
    encoding - the encoding to use, null means platform default
    
    Throws:
    
    IOException - in case of an I/O error
    
    UnsupportedEncodingException - if the encoding is not supported by the VM
    Since:
    
    2.4
  - writeStringToFile
```
public static void writeStringToFile(File file,
                     String data,
                     String encoding)
                              throws IOException
```
    Writes a String to a file creating the file if it does not exist.
    NOTE: As from v1.3, the parent directories of the file will be created if they do not exist.
    
    Parameters:
    file - the file to write
    data - the content to write to the file
    encoding - the encoding to use, null means platform default
    
    Throws:
    
    IOException - in case of an I/O error
    
    UnsupportedEncodingException - if the encoding is not supported by the VM
  - writeStringToFile
```
public static void writeStringToFile(File file,
                     String data,
                     Charset encoding,
                     boolean append)
                              throws IOException
```
    Writes a String to a file creating the file if it does not exist.
    
    Parameters:
    file - the file to write
    data - the content to write to the file
    encoding - the encoding to use, null means platform default
    append - if true, then the String will be added to the end of the file rather than overwriting
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    2.3
  - writeStringToFile
```
public static void writeStringToFile(File file,
                     String data,
                     String encoding,
                     boolean append)
                              throws IOException
```
    Writes a String to a file creating the file if it does not exist.
    
    Parameters:
    file - the file to write
    data - the content to write to the file
    encoding - the encoding to use, null means platform default
    append - if true, then the String will be added to the end of the file rather than overwriting
    
    Throws:
    
    IOException - in case of an I/O error
    
    UnsupportedCharsetException - thrown instead of .UnsupportedEncodingException in version 2.2 if the encoding is not supported by the VM
    Since:
    
    2.1
  - writeStringToFile
```
@Deprecated
public static void writeStringToFile(File file,
                                String data)
                              throws IOException
```
    Deprecated. 2.5 use writeStringToFile(File, String, Charset) instead
    
    Writes a String to a file creating the file if it does not exist using the default encoding for the VM.
    
    Parameters:
    file - the file to write
    data - the content to write to the file
    
    Throws:
    
    IOException - in case of an I/O error
  - writeStringToFile
```
@Deprecated
public static void writeStringToFile(File file,
                                String data,
                                boolean append)
                              throws IOException
```
    Deprecated. 2.5 use writeStringToFile(File, String, Charset, boolean) instead
    
    Writes a String to a file creating the file if it does not exist using the default encoding for the VM.
    
    Parameters:
    file - the file to write
    data - the content to write to the file
    append - if true, then the String will be added to the end of the file rather than overwriting
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    2.1
  - write
```
@Deprecated
public static void write(File file,
                    CharSequence data)
                  throws IOException
```
    Deprecated. 2.5 use write(File, CharSequence, Charset) instead
    
    Writes a CharSequence to a file creating the file if it does not exist using the default encoding for the VM.
    
    Parameters:
    file - the file to write
    data - the content to write to the file
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    2.0
  - write
```
@Deprecated
public static void write(File file,
                    CharSequence data,
                    boolean append)
                  throws IOException
```
    Deprecated. 2.5 use write(File, CharSequence, Charset, boolean) instead
    
    Writes a CharSequence to a file creating the file if it does not exist using the default encoding for the VM.
    
    Parameters:
    file - the file to write
    data - the content to write to the file
    append - if true, then the data will be added to the end of the file rather than overwriting
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    2.1
  - write
```
public static void write(File file,
         CharSequence data,
         Charset encoding)
                  throws IOException
```
    Writes a CharSequence to a file creating the file if it does not exist.
    
    Parameters:
    file - the file to write
    data - the content to write to the file
    encoding - the encoding to use, null means platform default
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    2.3
  - write
```
public static void write(File file,
         CharSequence data,
         String encoding)
                  throws IOException
```
    Writes a CharSequence to a file creating the file if it does not exist.
    
    Parameters:
    file - the file to write
    data - the content to write to the file
    encoding - the encoding to use, null means platform default
    
    Throws:
    
    IOException - in case of an I/O error
    
    UnsupportedEncodingException - if the encoding is not supported by the VM
    Since:
    
    2.0
  - write
```
public static void write(File file,
         CharSequence data,
         Charset encoding,
         boolean append)
                  throws IOException
```
    Writes a CharSequence to a file creating the file if it does not exist.
    
    Parameters:
    file - the file to write
    data - the content to write to the file
    encoding - the encoding to use, null means platform default
    append - if true, then the data will be added to the end of the file rather than overwriting
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    2.3
  - write
```
public static void write(File file,
         CharSequence data,
         String encoding,
         boolean append)
                  throws IOException
```
    Writes a CharSequence to a file creating the file if it does not exist.
    
    Parameters:
    file - the file to write
    data - the content to write to the file
    encoding - the encoding to use, null means platform default
    append - if true, then the data will be added to the end of the file rather than overwriting
    
    Throws:
    
    IOException - in case of an I/O error
    
    UnsupportedCharsetException - thrown instead of .UnsupportedEncodingException in version 2.2 if the encoding is not supported by the VM
    Since:
    
    2.1
  - writeByteArrayToFile
```
public static void writeByteArrayToFile(File file,
                        byte[] data)
                                 throws IOException
```
    Writes a byte array to a file creating the file if it does not exist.
    NOTE: As from v1.3, the parent directories of the file will be created if they do not exist.
    
    Parameters:
    file - the file to write to
    data - the content to write to the file
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    1.1
  - writeByteArrayToFile
```
public static void writeByteArrayToFile(File file,
                        byte[] data,
                        boolean append)
                                 throws IOException
```
    Writes a byte array to a file creating the file if it does not exist.
    
    Parameters:
    file - the file to write to
    data - the content to write to the file
    append - if true, then bytes will be added to the end of the file rather than overwriting
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    2.1
  - writeByteArrayToFile
```
public static void writeByteArrayToFile(File file,
                        byte[] data,
                        int off,
                        int len)
                                 throws IOException
```
    Writes len bytes from the specified byte array starting at offset off to a file, creating the file if it does not exist.
    
    Parameters:
    file - the file to write to
    data - the content to write to the file
    off - the start offset in the data
    len - the number of bytes to write
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    2.5
  - writeByteArrayToFile
```
public static void writeByteArrayToFile(File file,
                        byte[] data,
                        int off,
                        int len,
                        boolean append)
                                 throws IOException
```
    Writes len bytes from the specified byte array starting at offset off to a file, creating the file if it does not exist.
    
    Parameters:
    file - the file to write to
    data - the content to write to the file
    off - the start offset in the data
    len - the number of bytes to write
    append - if true, then bytes will be added to the end of the file rather than overwriting
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    2.5
  - writeLines
```
public static void writeLines(File file,
              String encoding,
              Collection<?> lines)
                       throws IOException
```
    Writes the toString() value of each item in a collection to the specified File line by line. The specified character encoding and the default line ending will be used.
    NOTE: As from v1.3, the parent directories of the file will be created if they do not exist.
    
    Parameters:
    file - the file to write to
    encoding - the encoding to use, null means platform default
    lines - the lines to write, null entries produce blank lines
    
    Throws:
    
    IOException - in case of an I/O error
    
    UnsupportedEncodingException - if the encoding is not supported by the VM
    Since:
    
    1.1
  - writeLines
```
public static void writeLines(File file,
              String encoding,
              Collection<?> lines,
              boolean append)
                       throws IOException
```
    Writes the toString() value of each item in a collection to the specified File line by line, optionally appending. The specified character encoding and the default line ending will be used.
    
    Parameters:
    file - the file to write to
    encoding - the encoding to use, null means platform default
    lines - the lines to write, null entries produce blank lines
    append - if true, then the lines will be added to the end of the file rather than overwriting
    
    Throws:
    
    IOException - in case of an I/O error
    
    UnsupportedEncodingException - if the encoding is not supported by the VM
    Since:
    
    2.1
  - writeLines
```
public static void writeLines(File file,
              Collection<?> lines)
                       throws IOException
```
    Writes the toString() value of each item in a collection to the specified File line by line. The default VM encoding and the default line ending will be used.
    
    Parameters:
    file - the file to write to
    lines - the lines to write, null entries produce blank lines
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    1.3
  - writeLines
```
public static void writeLines(File file,
              Collection<?> lines,
              boolean append)
                       throws IOException
```
    Writes the toString() value of each item in a collection to the specified File line by line. The default VM encoding and the default line ending will be used.
    
    Parameters:
    file - the file to write to
    lines - the lines to write, null entries produce blank lines
    append - if true, then the lines will be added to the end of the file rather than overwriting
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    2.1
  - writeLines
```
public static void writeLines(File file,
              String encoding,
              Collection<?> lines,
              String lineEnding)
                       throws IOException
```
    Writes the toString() value of each item in a collection to the specified File line by line. The specified character encoding and the line ending will be used.
    NOTE: As from v1.3, the parent directories of the file will be created if they do not exist.
    
    Parameters:
    file - the file to write to
    encoding - the encoding to use, null means platform default
    lines - the lines to write, null entries produce blank lines
    lineEnding - the line separator to use, null is system default
    
    Throws:
    
    IOException - in case of an I/O error
    
    UnsupportedEncodingException - if the encoding is not supported by the VM
    Since:
    
    1.1
  - writeLines
```
public static void writeLines(File file,
              String encoding,
              Collection<?> lines,
              String lineEnding,
              boolean append)
                       throws IOException
```
    Writes the toString() value of each item in a collection to the specified File line by line. The specified character encoding and the line ending will be used.
    
    Parameters:
    file - the file to write to
    encoding - the encoding to use, null means platform default
    lines - the lines to write, null entries produce blank lines
    lineEnding - the line separator to use, null is system default
    append - if true, then the lines will be added to the end of the file rather than overwriting
    
    Throws:
    
    IOException - in case of an I/O error
    
    UnsupportedEncodingException - if the encoding is not supported by the VM
    Since:
    
    2.1
  - writeLines
```
public static void writeLines(File file,
              Collection<?> lines,
              String lineEnding)
                       throws IOException
```
    Writes the toString() value of each item in a collection to the specified File line by line. The default VM encoding and the specified line ending will be used.
    
    Parameters:
    file - the file to write to
    lines - the lines to write, null entries produce blank lines
    lineEnding - the line separator to use, null is system default
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    1.3
  - writeLines
```
public static void writeLines(File file,
              Collection<?> lines,
              String lineEnding,
              boolean append)
                       throws IOException
```
    Writes the toString() value of each item in a collection to the specified File line by line. The default VM encoding and the specified line ending will be used.
    
    Parameters:
    file - the file to write to
    lines - the lines to write, null entries produce blank lines
    lineEnding - the line separator to use, null is system default
    append - if true, then the lines will be added to the end of the file rather than overwriting
    
    Throws:
    
    IOException - in case of an I/O error
    Since:
    
    2.1
  - forceDelete
```
public static void forceDelete(File file)
                        throws IOException
```
    Deletes a file. If file is a directory, delete it and all sub-directories.
    The difference between File.delete() and this method are:
    - A directory to be deleted does not have to be empty.
    - You get exceptions when a file or directory cannot be deleted. (java.io.File methods returns a boolean)
    Parameters:
    file - file or directory to delete, must not be null
    
    Throws:
    
    NullPointerException - if the directory is null
    
    FileNotFoundException - if the file was not found
    
    IOException - in case deletion is unsuccessful
  - forceDeleteOnExit
```
public static void forceDeleteOnExit(File file)
                              throws IOException
```
    Schedules a file to be deleted when JVM exits. If file is directory delete it and all sub-directories.
    
    Parameters:
    file - file or directory to delete, must not be null
    
    Throws:
    
    NullPointerException - if the file is null
    
    IOException - in case deletion is unsuccessful
  - forceMkdir
```
public static void forceMkdir(File directory)
                       throws IOException
```
    Makes a directory, including any necessary but nonexistent parent directories. If a file already exists with specified name but it is not a directory then an IOException is thrown. If the directory cannot be created (or does not already exist) then an IOException is thrown.
    
    Parameters:
    directory - directory to create, must not be null
    
    Throws:
    
    NullPointerException - if the directory is null
    
    IOException - if the directory cannot be created or the file already exists but is not a directory
  - forceMkdirParent
```
public static void forceMkdirParent(File file)
                             throws IOException
```
    Makes any necessary but nonexistent parent directories for a given File. If the parent directory cannot be created then an IOException is thrown.
    
    Parameters:
    file - file with parent to create, must not be null
    
    Throws:
    
    NullPointerException - if the file is null
    
    IOException - if the parent directory cannot be created
    Since:
    
    2.5
  - sizeOf
```
public static long sizeOf(File file)
```
    Returns the size of the specified file or directory. If the provided File is a regular file, then the file's length is returned. If the argument is a directory, then the size of the directory is calculated recursively. If a directory or subdirectory is security restricted, its size will not be included.
    Note that overflow is not detected, and the return value may be negative if overflow occurs. See sizeOfAsBigInteger(File) for an alternative method that does not overflow.
    
    Parameters:
    file - the regular file or directory to return the size of (must not be null).
    
    Returns:
    the length of the file, or recursive size of the directory, provided (in bytes).
    
    Throws:
    
    NullPointerException - if the file is null
    
    IllegalArgumentException - if the file does not exist.
    Since:
    
    2.0
  - sizeOfAsBigInteger
```
public static BigInteger sizeOfAsBigInteger(File file)
```
    Returns the size of the specified file or directory. If the provided File is a regular file, then the file's length is returned. If the argument is a directory, then the size of the directory is calculated recursively. If a directory or subdirectory is security restricted, its size will not be included.
    
    Parameters:
    file - the regular file or directory to return the size of (must not be null).
    
    Returns:
    the length of the file, or recursive size of the directory, provided (in bytes).
    
    Throws:
    
    NullPointerException - if the file is null
    
    IllegalArgumentException - if the file does not exist.
    Since:
    
    2.4
  - sizeOfDirectory
```
public static long sizeOfDirectory(File directory)
```
    Counts the size of a directory recursively (sum of the length of all files).
    Note that overflow is not detected, and the return value may be negative if overflow occurs. See sizeOfDirectoryAsBigInteger(File) for an alternative method that does not overflow.
    
    Parameters:
    directory - directory to inspect, must not be null
    
    Returns:
    size of directory in bytes, 0 if directory is security restricted, a negative number when the real total is greater than Long.MAX_VALUE.
    
    Throws:
    
    NullPointerException - if the directory is null
  - sizeOfDirectoryAsBigInteger
```
public static BigInteger sizeOfDirectoryAsBigInteger(File directory)
```
    Counts the size of a directory recursively (sum of the length of all files).
    
    Parameters:
    directory - directory to inspect, must not be null
    
    Returns:
    size of directory in bytes, 0 if directory is security restricted.
    
    Throws:
    
    NullPointerException - if the directory is null
    Since:
    
    2.4
  - isFileNewer
```
public static boolean isFileNewer(File file,
                  File reference)
```
    Tests if the specified File is newer than the reference File.
    
    Parameters:
    file - the File of which the modification date must be compared, must not be null
    reference - the File of which the modification date is used, must not be null
    
    Returns:
    true if the File exists and has been modified more recently than the reference File
    
    Throws:
    
    IllegalArgumentException - if the file is null
    
    IllegalArgumentException - if the reference file is null or doesn't exist
  - isFileNewer
```
public static boolean isFileNewer(File file,
                  Date date)
```
    Tests if the specified File is newer than the specified Date.
    
    Parameters:
    file - the File of which the modification date must be compared, must not be null
    date - the date reference, must not be null
    
    Returns:
    true if the File exists and has been modified after the given Date.
    
    Throws:
    
    IllegalArgumentException - if the file is null
    
    IllegalArgumentException - if the date is null
  - isFileNewer
```
public static boolean isFileNewer(File file,
                  long timeMillis)
```
    Tests if the specified File is newer than the specified time reference.
    
    Parameters:
    file - the File of which the modification date must be compared, must not be null
    timeMillis - the time reference measured in milliseconds since the epoch (00:00:00 GMT, January 1, 1970)
    
    Returns:
    true if the File exists and has been modified after the given time reference.
    
    Throws:
    
    IllegalArgumentException - if the file is null
  - isFileOlder
```
public static boolean isFileOlder(File file,
                  File reference)
```
    Tests if the specified File is older than the reference File.
    
    Parameters:
    file - the File of which the modification date must be compared, must not be null
    reference - the File of which the modification date is used, must not be null
    
    Returns:
    true if the File exists and has been modified before the reference File
    
    Throws:
    
    IllegalArgumentException - if the file is null
    
    IllegalArgumentException - if the reference file is null or doesn't exist
  - isFileOlder
```
public static boolean isFileOlder(File file,
                  Date date)
```
    Tests if the specified File is older than the specified Date.
    
    Parameters:
    file - the File of which the modification date must be compared, must not be null
    date - the date reference, must not be null
    
    Returns:
    true if the File exists and has been modified before the given Date.
    
    Throws:
    
    IllegalArgumentException - if the file is null
    
    IllegalArgumentException - if the date is null
  - isFileOlder
```
public static boolean isFileOlder(File file,
                  long timeMillis)
```
    Tests if the specified File is older than the specified time reference.
    
    Parameters:
    file - the File of which the modification date must be compared, must not be null
    timeMillis - the time reference measured in milliseconds since the epoch (00:00:00 GMT, January 1, 1970)
    
    Returns:
    true if the File exists and has been modified before the given time reference.
    
    Throws:
    
    IllegalArgumentException - if the file is null
  - checksumCRC32
```
public static long checksumCRC32(File file)
                          throws IOException
```
    Computes the checksum of a file using the CRC32 checksum routine. The value of the checksum is returned.
    
    Parameters:
    file - the file to checksum, must not be null
    
    Returns:
    the checksum value
    
    Throws:
    
    NullPointerException - if the file or checksum is null
    
    IllegalArgumentException - if the file is a directory
    
    IOException - if an IO error occurs reading the file
    Since:
    
    1.3
  - checksum
```
public static Checksum checksum(File file,
                Checksum checksum)
                         throws IOException
```
    Computes the checksum of a file using the specified checksum object. Multiple files may be checked using one Checksum instance if desired simply by reusing the same checksum object. For example:
```
   long csum = FileUtils.checksum(file, new CRC32()).getValue();
 
```
    Parameters:
    file - the file to checksum, must not be null
    checksum - the checksum object to be used, must not be null
    
    Returns:
    the checksum specified, updated with the content of the file
    
    Throws:
    
    NullPointerException - if the file or checksum is null
    
    IllegalArgumentException - if the file is a directory
    
    IOException - if an IO error occurs reading the file
    Since:
    
    1.3
  - moveDirectory
```
public static void moveDirectory(File srcDir,
                 File destDir)
                          throws IOException
```
    Moves a directory.
    When the destination directory is on another file system, do a "copy and delete".
    
    Parameters:
    srcDir - the directory to be moved
    destDir - the destination directory
    
    Throws:
    
    NullPointerException - if source or destination is null
    
    FileExistsException - if the destination directory exists
    
    IOException - if source or destination is invalid
    
    IOException - if an IO error occurs moving the file
    Since:
    
    1.4
  - moveDirectoryToDirectory
```
public static void moveDirectoryToDirectory(File src,
                            File destDir,
                            boolean createDestDir)
                                     throws IOException
```
    Moves a directory to another directory.
    
    Parameters:
    src - the file to be moved
    destDir - the destination file
    createDestDir - If true create the destination directory, otherwise if false throw an IOException
    
    Throws:
    
    NullPointerException - if source or destination is null
    
    FileExistsException - if the directory exists in the destination directory
    
    IOException - if source or destination is invalid
    
    IOException - if an IO error occurs moving the file
    Since:
    
    1.4
  - moveFile
```
public static void moveFile(File srcFile,
            File destFile)
                     throws IOException
```
    Moves a file.
    When the destination file is on another file system, do a "copy and delete".
    
    Parameters:
    srcFile - the file to be moved
    destFile - the destination file
    
    Throws:
    
    NullPointerException - if source or destination is null
    
    FileExistsException - if the destination file exists
    
    IOException - if source or destination is invalid
    
    IOException - if an IO error occurs moving the file
    Since:
    
    1.4
  - moveFileToDirectory
```
public static void moveFileToDirectory(File srcFile,
                       File destDir,
                       boolean createDestDir)
                                throws IOException
```
    Moves a file to a directory.
    
    Parameters:
    srcFile - the file to be moved
    destDir - the destination file
    createDestDir - If true create the destination directory, otherwise if false throw an IOException
    
    Throws:
    
    NullPointerException - if source or destination is null
    
    FileExistsException - if the destination file exists
    
    IOException - if source or destination is invalid
    
    IOException - if an IO error occurs moving the file
    Since:
    
    1.4
  - moveToDirectory
```
public static void moveToDirectory(File src,
                   File destDir,
                   boolean createDestDir)
                            throws IOException
```
    Moves a file or directory to the destination directory.
    When the destination is on another file system, do a "copy and delete".
    
    Parameters:
    src - the file or directory to be moved
    destDir - the destination directory
    createDestDir - If true create the destination directory, otherwise if false throw an IOException
    
    Throws:
    
    NullPointerException - if source or destination is null
    
    FileExistsException - if the directory or file exists in the destination directory
    
    IOException - if source or destination is invalid
    
    IOException - if an IO error occurs moving the file
    Since:
    
    1.4
  - isSymlink
```
public static boolean isSymlink(File file)
                         throws IOException
```
    Determines whether the specified file is a Symbolic Link rather than an actual file.
    Will not return true if there is a Symbolic Link anywhere in the path, only if the specific file is.
    When using jdk1.7, this method delegates to boolean java.nio.file.Files.isSymbolicLink(Path path) Note: the current implementation always returns false if running on jkd1.6 and the system is detected as Windows using FilenameUtils.isSystemWindows()
    For code that runs on Java 1.7 or later, use the following method instead:
    boolean java.nio.file.Files.isSymbolicLink(Path path)
    
    Parameters:
    file - the file to check
    
    Returns:
    true if the file is a Symbolic Link
    
    Throws:
    
    IOException - if an IO error occurs while checking the file
    Since:
    
    2.0

Class FileUtils

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ONE_GB_BI

ONE_TB

ONE_TB_BI

ONE_PB

ONE_PB_BI

ONE_EB

ONE_EB_BI

ONE_ZB

ONE_YB

EMPTY_FILE_ARRAY

Constructor Detail

FileUtils

Method Detail

getFile

getFile

getTempDirectoryPath

getTempDirectory

getUserDirectoryPath

getUserDirectory

openInputStream

openOutputStream

openOutputStream

byteCountToDisplaySize

byteCountToDisplaySize

touch

convertFileCollectionToFileArray

listFiles

listFilesAndDirs

iterateFiles

iterateFilesAndDirs

listFiles

iterateFiles

contentEquals

contentEqualsIgnoreEOL

toFile

toFiles

toURLs

copyFileToDirectory

copyFileToDirectory

copyFile

copyFile

copyFile

copyDirectoryToDirectory

copyDirectory

copyDirectory

copyDirectory

Example: Copy directories only

Example: Copy directories and txt files

copyDirectory

Example: Copy directories only

Example: Copy directories and txt files

copyURLToFile

copyURLToFile

copyInputStreamToFile

copyToFile

deleteDirectory

deleteQuietly

directoryContains

cleanDirectory

waitFor

readFileToString

readFileToString

readFileToString

readFileToByteArray

readLines

readLines

readLines

lineIterator

lineIterator