Android 退出程序方式——再按一次退出

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
long exitTime = 0;
if(keyCode == KeyEvent.KEYCODE_BACK && event.getAction() == KeyEvent.ACTION_DOWN){
if((System.currentTimeMillis()-exitTime) > 2000){
Toast.makeText(getApplicationContext(), "再按一次退出程序", Toast.LENGTH_SHORT).show();
exitTime = System.currentTimeMillis();
} else {
MyApplication.getInstance().exit();
}
return true;
}
return super.onKeyDown(keyCode, event);
}

之前不知道下面这个方法：

private long mLastExitTime;

@Override
public void onBackPressed() {
if (System.currentTimeMillis() - mLastExitTime < 2000) {
super.onBackPressed();
} else {
mLastExitTime = System.currentTimeMillis();
ToastUtil.showNormalToast(this, getString(R.string.exit_toast));
}
}