org.apache.commons.io.filefilter

This package defines an interface (IOFileFilter) that combines both {@link java.io.FileFilter} and {@link java.io.FilenameFilter}.

Interface Summary
ConditionalFileFilter	Defines operations for conditional file filters.
IOFileFilter	An interface which brings the FileFilter and FilenameFilter interfaces together.

Class Summary
AbstractFileFilter	An abstract class which implements the Java FileFilter and FilenameFilter interfaces via the IOFileFilter interface.
AgeFileFilter	Filters files based on a cutoff time, can filter either newer files or files equal to or older.
AndFileFilter	A {@link java.io.FileFilter} providing conditional AND logic across a list of file filters.
CanReadFileFilter	This filter accepts `File`s that can be read.
CanWriteFileFilter	This filter accepts `File`s that can be written to.
DelegateFileFilter	This class turns a Java FileFilter or FilenameFilter into an IO FileFilter.
DirectoryFileFilter	This filter accepts `File`s that are directories.
EmptyFileFilter	This filter accepts files or directories that are empty.
FalseFileFilter	A file filter that always returns false.
FileFileFilter	This filter accepts `File`s that are files (not directories).
FileFilterUtils	Useful utilities for working with file filters.
HiddenFileFilter	This filter accepts `File`s that are hidden.
NameFileFilter	Filters filenames for a certain name.
NotFileFilter	This filter produces a logical NOT of the filters specified.
OrFileFilter	A {@link java.io.FileFilter} providing conditional OR logic across a list of file filters.
PrefixFileFilter	Filters filenames for a certain prefix.
SizeFileFilter	Filters files based on size, can filter either smaller files or files equal to or larger than a given threshold.
SuffixFileFilter	Filters files based on the suffix (what the filename ends with).
TrueFileFilter	A file filter that always returns true.
WildcardFileFilter	Filters files using the supplied wildcards.
WildcardFilter	Filters files using the supplied wildcards.

Package org.apache.commons.io.filefilter Description:

This package defines an interface (IOFileFilter) that combines both {@link java.io.FileFilter} and {@link java.io.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 {@link java.awt.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

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]);
  }

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]);
  }

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