Java Coding Problems

Filtering via FileFilter

FileFilter is another functional interface that can be used to filter files and folders. For example, let's filter only folders:

File[] folders = path.toFile().listFiles(new FileFilter() {  @Override  public boolean accept(File file) {    return file.isDirectory();  }});

We can do the same in functional-style:

File[] folders = path.toFile().listFiles((File file)   -> file.isDirectory());

Let's make this more concise:

File[] folders = path.toFile().listFiles(f -> f.isDirectory());

Finally, we can do this via member reference:

File[] folders = path.toFile().listFiles(File::isDirectory);