Listing files in a directory matching a pattern in Java

Question

I'm looking for a way to get a list of files that match a pattern (pref regex) in a given directory.

I've found a tutorial online that uses apache's commons-io package with the following code:

Collection getAllFilesThatMatchFilenameExtension(String directoryName, String extension)
{
  File directory = new File(directoryName);
  return FileUtils.listFiles(directory, new WildcardFileFilter(extension), null);
}

But that just returns a base collection (According to the docs it's a collection of java.io.File). Is there a way to do this that returns a type safe generic collection?

Answer 1

See File#listFiles(FilenameFilter).

File dir = new File(".");
File [] files = dir.listFiles(new FilenameFilter() {
    @Override
    public boolean accept(File dir, String name) {
        return name.endsWith(".xml");
    }
});

for (File xmlfile : files) {
    System.out.println(xmlfile);
}

Answer 2

The following code will create a list of files based on the accept method of the FileNameFilter.

List<File> list = Arrays.asList(dir.listFiles(new FilenameFilter(){
        @Override
        public boolean accept(File dir, String name) {
            return name.endsWith(".exe"); // or something else
        }}));

Answer 3

What about a wrapper around your existing code:

public Collection<File> getMatchingFiles( String directory, String extension ) {
     return new ArrayList<File>()( 
         getAllFilesThatMatchFilenameExtension( directory, extension ) );
 }

I will throw a warning though. If you can live with that warning, then you're done.