Cocos2d-x back button twice click exit

AppActivity.java

/****************************************************************************
 Copyright (c) 2008-2010 Ricardo Quesada
 Copyright (c) 2010-2012 cocos2d-x.org
 Copyright (c) 2011      Zynga Inc.
 Copyright (c) 2013-2014 Chukong Technologies Inc.

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package org.cocos2dx.cpp;

import android.util.Log;
import android.widget.Toast;
import android.os.Handler;
import android.os.Bundle;
import android.view.KeyEvent;

import org.cocos2dx.lib.Cocos2dxActivity;
import org.cocos2dx.lib.Cocos2dxGLSurfaceView;

public class AppActivity extends Cocos2dxActivity {
    private boolean doubleBackToExitPressedOnce = false;

    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
    }

    public Cocos2dxGLSurfaceView onCreateView() {
        Cocos2dxGLSurfaceView glSurfaceView = new Cocos2dxGLSurfaceView(this);

        // create stencil buffer
        glSurfaceView.setEGLConfigChooser(5, 6, 5, 0, 16, 8);

        return glSurfaceView;
    }

    @Override
    public boolean dispatchKeyEvent(KeyEvent event) {
        if(event.getKeyCode()==KeyEvent.KEYCODE_BACK && event.getAction() == KeyEvent.ACTION_UP) {
            if (doubleBackToExitPressedOnce) {
                //Log.d("robot", "back key clicked");
                System.exit(0);
            }
            this.doubleBackToExitPressedOnce = true;
            Toast.makeText(this, "Press once again to exit", Toast.LENGTH_SHORT).show();
            new Handler().postDelayed(new Runnable() {
                @Override
                public void run() {
                    doubleBackToExitPressedOnce=false;
                }
            }, 2000);
            return true;
        }
        else {
            return super.dispatchKeyEvent(event);
        }
    }
}