第一种方式
// 定义一个变量，来标识是否退出
private static boolean isExit = false;
Handler mHandler = 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;
Toast.makeText(getApplicationContext(), "再按一次退出程序",
Toast.LENGTH_SHORT).show();
// 利用handler延迟发送更改状态信息
mHandler.sendEmptyMessageDelayed(0, 2000);
} else {
exit(this);
}
return false;
}
return super.onKeyDown(keyCode, event);}
第二种方式
//保存点击的时间
private long exitTime = 0;
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
if ((System.currentTimeMillis() - exitTime) > 2000) {
Toast.makeText(getApplicationContext(), "再按一次退出程序",
Toast.LENGTH_SHORT).show();
exitTime = System.currentTimeMillis();
} else {
exit();
}
return false;
}
return super.onKeyDown(keyCode, event);
}