public class Foo {

    public static void bar(final Runnable runnable) {
    runnable.run();
  }
}

class Bar {
  public static void main(String[] args) {
      Foo.bar(new Runnable() {
        @Override
        public void run() {
          doRun();
        }
  
        private void doRun() {
          // Woo-hoo
        }
      });
  }
}