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);

}