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Package org.apache.commons.io.filefilter

Provides the an interface IOFileFilter that combines both FileFilter and FilenameFilter.

See: Description

Package org.apache.commons.io.filefilter Description

Provides the an interface IOFileFilter that combines both FileFilter and FilenameFilter.

Besides that the package offers a series of ready-to-use implementations of the IOFileFilter interface including implementation that allow you to combine other such filters.

These filter can be used to list files or in FileDialog, for example.

There are a number of 'primitive' filters:
DirectoryFilter Only accept directories
PrefixFileFilter Filter based on a prefix
SuffixFileFilter Filter based on a suffix
NameFileFilter Filter based on a filename
WildcardFileFilter Filter based on wildcards
AgeFileFilter Filter based on last modified time of file
SizeFileFilter Filter based on file size
And there are five 'boolean' filters:
TrueFileFilter Accept all files
FalseFileFilter Accept no files
NotFileFilter Applies a logical NOT to an existing filter
AndFileFilter Combines two filters using a logical AND
OrFileFilter Combines two filter using a logical OR

Using Classic IO

These boolean FilenameFilters can be nested, to allow arbitrary expressions. For example, here is how one could print all non-directory files in the current directory, starting with "A", and ending in ".java" or ".class":

 File dir = new File(".");
 String[] files = dir.list(
 new AndFileFilter(
 new AndFileFilter(
 new PrefixFileFilter("A"),
 new OrFileFilter(
 new SuffixFileFilter(".class"),
 new SuffixFileFilter(".java")
 )
 ),
 new NotFileFilter(
 new DirectoryFileFilter()
 )
 )
 );
 for (int i=0; i<files.length; i++) {
 System.out.println(files[i]);
 }
 

You can alternatively build a filter tree using the "and", "or", and "not" methods on filters themselves:

 File dir = new File(".");
 String[] files = dir.list(
 new AndFileFilter(
 new PrefixFileFilter("A").and(
 new SuffixFileFilter(".class").or(new SuffixFileFilter(".java"))),
 new DirectoryFileFilter().not()
 )
 );
 for (int i=0; i<files.length; i++) {
 System.out.println(files[i]);
 }
 

This package also contains a utility class: FileFilterUtils. It allows you to use all file filters without having to put them in the import section. Here's how the above example will look using FileFilterUtils:

 File dir = new File(".");
 String[] files = dir.list(
 FileFilterUtils.andFileFilter(
 FileFilterUtils.andFileFilter(
 FileFilterUtils.prefixFileFilter("A"),
 FileFilterUtils.orFileFilter(
 FileFilterUtils.suffixFileFilter(".class"),
 FileFilterUtils.suffixFileFilter(".java")
 )
 ),
 FileFilterUtils.notFileFilter(
 FileFilterUtils.directoryFileFilter()
 )
 )
 );
 for (int i=0; i<files.length; i++) {
 System.out.println(files[i]);
 }
 

Using NIO

You can combine Java file tree walking by using java.nio.file.Files.walk() APIs with filters:

 final Path dir = Paths.get("");
 // We are interested in files older than one day
 final long cutoff = System.currentTimeMillis() - (24 * 60 * 60 * 1000);
 final AccumulatorPathVisitor visitor = AccumulatorPathVisitor.withLongCounters(new AgeFileFilter(cutoff));
 //
 // Walk one dir
 Files.walkFileTree(dir, Collections.emptySet(), 1, visitor);
 System.out.println(visitor.getPathCounters());
 System.out.println(visitor.getFileList());
 //
 visitor.getPathCounters().reset();
 //
 // Walk dir tree
 Files.walkFileTree(dir, visitor);
 System.out.println(visitor.getPathCounters());
 System.out.println(visitor.getDirList());
 System.out.println(visitor.getFileList());
 

There are a few other goodies in that class so please have a look at the documentation in detail.

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