Android点击两次返回键退出

private static Boolean isQuit = false;
Timer timer = new Timer();

public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
if (isQuit == false) {
isQuit = true;
Toast.makeText(getBaseContext(), "再按一次退出?", Toast.LENGTH_SHORT).show();
TimerTask task = null;
task = new TimerTask() {
@Override
public void run() {
isQuit = false;
}
};
timer.schedule(task, 2000);
} else {
ActivityControler.finishAllActivity();
}
}
return true;
}