/**
 * 所有activity的基類
 * 
 **/
public abstract class BaseActivity extends AppCompatActivity {
    @Override
     protected void onCreate(Bundle savedInstanceState, int resource) {
                super.onCreate(savedInstanceState);
         }
    @Override
    protected void onRestart() {
        super.onRestart();
        if(App.exit==true){
            finish();
        }
    }
}

/**
 * 開啟的第一個activity中，
 **/
 
 public abstract class SplashActivity extends AppCompatActivity {
    @Override
     protected void onCreate(Bundle savedInstanceState, int resource) {
                super.onCreate(savedInstanceState);
                App.exit = false;
    }
    
}

/**
 * 需要關閉的主頁activity中，
 * 
 **/
    public abstract class MainActivity extends AppCompatActivity {
      private boolean  isExit; 
    @Override
     protected void onCreate(Bundle savedInstanceState, int resource) {
                super.onCreate(savedInstanceState);
             
    }
    

   public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            exitBy2Click();
        }
        return false;
    }

    private void exitBy2Click() {
      
        if (isExit == false) {
            isExit = true; // 準備退出
            Toast.makeText(this, "再次點選退出", Toast.LENGTH_SHORT).show();

            tExit = new Timer();
            tExit.schedule(new TimerTask() {
                public void run() {
                    isExit = false; // 取消退出
                }
            }, 2000); // 如果2秒鐘內沒有按下返回鍵，則啟動定時器取消掉剛才執行的任務
        } else {
        
             App.exit = true;
            finish();
        }

    }
  }