title: Fastest way to find all direct subdirectories of a directory
body: <p>Performance measurement showed that I spend a lot of time finding subdirectories. I use</p>
  
  <pre><code>File[] subDirArray = file.listFiles(new FileFilter()
  {
    @Override
    public boolean accept(File pathname)
    {
      return pathname.isDirectory();
    }
  });
  </code></pre>
  
  <p>to find all direct subdirectories of a given directory. Is there a way to do this faster (in Java 7)?</p>