code: private void collectFiles( File folder, final List<File> collectedFiles )
      {
          folder.listFiles( new FileFilter()
          {
              @Override
              public boolean accept( File file )
              {
                  if ( file.isDirectory() )
                  {
                      collectFiles( file, collectedFiles );
                  }
                  else if ( file.isFile() )
                  {
                      if ( !file.getName().endsWith( ".class" ) )
                      {
                          collectedFiles.add( file );
                      }
                  }
                  return false;
              }
          } );
  
      }
docs: Collect all Files from Folder (recursively) that are not class files.