static class MessageListener {
    private String triggerMessage;
    private Runnable runnable;

    MessageListener(String message, Runnable runnable) {
        this.triggerMessage = message;
        this.runnable = runnable;
    }

    private void trigger(String message) {
        if (message.equals(triggerMessage)) {
            runnable.run();
        }
    }
}

ws.setListener(new IPDWebSocket.MessageListener("disconnect", new Runnable() {
        @Override
        public void run() {
          Log.e("xx", "Received message: ");
        }
    }
  )
);

for (int nr=0; nr < listeners.size(); nr++) {
    listeners.get(nr).trigger(msg);
}