gistfile1.java

ContactListener contactListener = new ContactListener() {
		int bodyContactSemaphore = 0;

		@Override
		public void beginContact(Contact contact) {
      bodyContactSemaphore++;
      
      // check if the contact bodies are valid
      // if they are, take action according to
      // the user data of the bodies.
		}
    
    @Override
  	public void endContact(Contact contact) {
      bodyContactSemaphore--;
  	}
    
    .
    .
    .
}