android按两次返回键退出程序

android按两次返回键退出程序

 现在有很多程序都使用按两次返回键退出程序，下面介绍两种办法实现按两次返回键退出程序：
1.第一种方法（个人推荐）：

private long mExitTime;

@Override

    public boolean onKeyDown(int keyCode, KeyEvent event)

    {

    // TODO Auto-generated method stub

if (keyCode == KeyEvent.KEYCODE_BACK

        && event.getAction() == KeyEvent.ACTION_DOWN) {

if ((System.currentTimeMillis() - mExitTime) > 2000) {

//Toast.makeText(this, "再按一次返回键退出", Toast.LENGTH_SHORT).show();

ToastShowMessage.showShortToast(this, "再按一次返回键退出");

mExitTime = System.currentTimeMillis();

} else {

finish();

System.exit(0);

}

return true;

}

    return super.onKeyDown(keyCode, event);

    }

第二种方法是：

private static Boolean isQuit = false;

private Timer timer = new Timer();

@Override

public boolean onKeyDown(int keyCode, KeyEvent event) {

if (keyCode == KeyEvent.KEYCODE_BACK) {

if (isQuit == false) {

isQuit = true;

Toast.makeText(getBaseContext(), "再次按返回键退出软件",

Toast.LENGTH_SHORT).show();

TimerTask task = null;

task = new TimerTask() {

@Override

public void run() {

isQuit = false;

}

};

timer.schedule(task, 2000);

} else {

finish();

}

}

return false;

}

这种方法中，也可以将Timer换乘hander

private static Boolean isQuit = false;

private Handler mTimeHandler;

private Runnable mTimeRunnable;

@Override

public boolean onKeyDown(int keyCode, KeyEvent event) {

if(keyCode == KeyEvent.KEYCODE_BACK){

mTimeHandler = new Handler();

mTimeRunnable = new Runnable() {

@Override

public void run() {

// TODO Auto-generated method stub

isQuit = false;

}

};

if(isQuit == false){

isQuit = true;

Toast.makeText(getApplicationContext(), "再按一次返回键退出程序", Toast.LENGTH_SHORT).show();

mTimeHandler.postDelayed(mTimeRunnable, 2000);

}else {

finish();

}

return true;

}

return super.onKeyUp(keyCode, event);

}