org.apache.commons.io.input
Class ReversedLinesFileReader

java.lang.Object
  extended by org.apache.commons.io.input.ReversedLinesFileReader
All Implemented Interfaces:
Closeable

public class ReversedLinesFileReader
extends Object
implements Closeable

Reads lines in a file reversely (similar to a BufferedReader, but starting at the last line). Useful for e.g. searching in log files.

Since:
2.2

Constructor Summary
ReversedLinesFileReader(File file)
          Creates a ReversedLinesFileReader with default block size of 4KB and the platform's default encoding.
ReversedLinesFileReader(File file, int blockSize, Charset encoding)
          Creates a ReversedLinesFileReader with the given block size and encoding.
ReversedLinesFileReader(File file, int blockSize, String encoding)
          Creates a ReversedLinesFileReader with the given block size and encoding.
 
Method Summary
 void close()
          Closes underlying resources.
 String readLine()
          Returns the lines of the file from bottom to top.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ReversedLinesFileReader

public ReversedLinesFileReader(File file)
                        throws IOException
Creates a ReversedLinesFileReader with default block size of 4KB and the platform's default encoding.

Parameters:
file - the file to be read
Throws:
IOException - if an I/O error occurs

ReversedLinesFileReader

public ReversedLinesFileReader(File file,
                               int blockSize,
                               Charset encoding)
                        throws IOException
Creates a ReversedLinesFileReader with the given block size and encoding.

Parameters:
file - the file to be read
blockSize - size of the internal buffer (for ideal performance this should match with the block size of the underlying file system).
encoding - the encoding of the file
Throws:
IOException - if an I/O error occurs
Since:
2.3

ReversedLinesFileReader

public ReversedLinesFileReader(File file,
                               int blockSize,
                               String encoding)
                        throws IOException
Creates a ReversedLinesFileReader with the given block size and encoding.

Parameters:
file - the file to be read
blockSize - size of the internal buffer (for ideal performance this should match with the block size of the underlying file system).
encoding - the encoding of the file
Throws:
IOException - if an I/O error occurs
UnsupportedCharsetException - thrown instead of UnsupportedEncodingException in version 2.2 if the encoding is not supported.
Method Detail

readLine

public String readLine()
                throws IOException
Returns the lines of the file from bottom to top.

Returns:
the next line or null if the start of the file is reached
Throws:
IOException - if an I/O error occurs

close

public void close()
           throws IOException
Closes underlying resources.

Specified by:
close in interface Closeable
Throws:
IOException - if an I/O error occurs


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