public FilesystemWalker(final File startingDirectory){
  if (startingDirectory == null) {
    throw new IllegalArgumentException("startingDirectory must be specified");
  }
  if (!startingDirectory.isDirectory()) {
    final String messageFormat="the specified starting directory [{0}] is not a directory";
    final String message=MessageFormat.format(messageFormat,startingDirectory.getAbsolutePath());
    throw new IllegalArgumentException(message);
  }
  this.startingDirectory=startingDirectory;
}

public FilesystemWalker ( final File startingDirectory ) { if ( startingDirectory == null ) { throw new IllegalArgumentException ( "startingDirectory must be specified" ) ; } if ( ! startingDirectory . isDirectory ( ) ) { final String messageFormat = "the specified starting directory [{0}] is not a directory" ; final String message = MessageFormat . format ( messageFormat , startingDirectory . getAbsolutePath ( ) ) ; throw new IllegalArgumentException ( message ) ; } this . startingDirectory = startingDirectory ; }
create a new filesystemwalker that will walk beginning at the given directory .
