第一种（Handler+标志位）

复制代码 代码如下:

private boolean isExit;

private Handler handler;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

handler = new Handler(){

@Override

public void handleMessage(Message msg) {

super.handleMessage(msg);

isExit = false;

}

};

}

public boolean onKeyDown(int keyCode, KeyEvent event) {

if(keyCode==KeyEvent.KEYCODE_BACK){

if(!isExit){

isExit = true;

handler.sendEmptyMessageDelayed(0, 1500);

Toast.makeText(this, "再按一次推出程序", 1000).show();

return false;

}else{

finish();

}

}

return super.onKeyDown(keyCode, event);

}

第二种（记录点击的时间）

复制代码 代码如下:

private long exitTimeMillis = System.currentTimeMillis();

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

}

@Override

public boolean onKeyDown(int keyCode, KeyEvent event) {

if(keyCode==KeyEvent.KEYCODE_BACK){

long currentTime = System.currentTimeMillis();

if(currentTime-exitTimeMillis==0||currentTime-exitTimeMillis>1500){

exitTimeMillis = System.currentTimeMillis();

Toast.makeText(this, "再按一次推出程序", 1000).show();

return false;

}else{

finish();

}

}

return super.onKeyDown(keyCode, event);

}