java - 不会继续执行 ACTION_DOWN 上的语句

Question

我正在为我的任务制作一款月球着陆器游戏

我有一个按钮并为其设置了一个 onTouchListener (不是 onClick) 当按钮按下或 ACTION_DOWN 时，火箭会向上飞行并在 ACTION_UP 时停止加速。

目前它只在 ACTION_DOWN 上执行一次，因此它的行为就像一个 onClick 按钮。

如有任何帮助，我们将不胜感激

• gView 是游戏类的一个实例，所有魔法都在这里发生

• gView.mainThruster() 调用游戏类中使飞船向上飞行的方法，例如 Y -= 10；

  mThrust = (Button) findViewById(R.id.mainThrustBtn);    
  mThrust.setOnTouchListener(new OnTouchListener(){
  @Override
  public boolean onTouch(View v, MotionEvent event) {
  
      if(event.getAction() == MotionEvent.ACTION_DOWN) {
          if(fuel > 0){
  
                gView.checkFuel(fuel);
            gView.mainThruster();
            mThrustSound.start();
            fuel -= 0.5;
            fuelGauge.setProgress((int)fuel);
            }
       }
       else if(event.getAction() == MotionEvent.ACTION_UP){
  
          mThrustSound.pause();
          //mThrustSound.release();   
       }
       else{
          //do nothing
       }
          return true;
       }
   });
  

Answer 1

文档清楚地说明了这一点:

On pointing devices with source class SOURCE_CLASS_POINTER such as touch screens, the pointer coordinates specify absolute positions such as view X/Y coordinates. Each complete gesture is represented by a sequence of motion events with actions that describe pointer state transitions and movements. A gesture starts with a motion event with ACTION_DOWN that provides the location of the first pointer down. As each additional pointer that goes down or up, the framework will generate a motion event with ACTION_POINTER_DOWN or ACTION_POINTER_UP accordingly. Pointer movements are described by motion events with ACTION_MOVE. Finally, a gesture end either when the final pointer goes up as represented by a motion event with ACTION_UP or when gesture is canceled with ACTION_CANCEL.

因此，您应该期望获得一个ACTION_DOWN事件，然后是多个ACTION_MOVE事件。听起来基本上，如果你想处理 Action ，你也需要响应 ACTION_MOVE ，并且如果你想在触摸发生时连续做某事，你可能想要某种计时器事件(因为您不会生成新的运动事件 - 仅触摸和按住不涉及运动)。