Android(安卓)再按一次退出程序

方式一（Handler+标志位）：

public class MainActivity extends Activity {

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) {
// TODO Auto-generated method stub
super.handleMessage(msg);
isExit = false;
}
};

}

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
if (!isExit) {
isExit = true;
handler.sendEmptyMessageDelayed(0, 1500);
Toast.makeText(this, "再按一次退出程序", 1000).show();
return false;
} else {
finish();
}

}
return super.onKeyDown(keyCode, event);
}

}

方式二（记录点击的时间）：

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, "再按一次退出程序", 1000).show();
return false;
}else{
finish();
}
}
return super.onKeyDown(keyCode, event);
}

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