android - 从数组列表中删除对象 - 并发修改异常

Question

我正在制作游戏，我阅读了所有关于在遍历数组列表时删除/修改数组列表时并发修改异常的内容，但我仍然有问题。
我想在触摸屏幕时删除对象并且对象 x,y 与触摸的 x,y 对齐但是当发生这种情况时，我将触摸的对象放入一个新的集合中以进行删除，但它会删除(有时)对象但是3-4 秒后，这对我来说意义不大，并且还会在 10-15 秒后给出并发修改异常。如果有人注意到我的代码中有任何内容，请告诉我...

public void checkTouch(MotionEvent arg1) {
        int x = (int) arg1.getX();
        int y = (int) arg1.getY();
        synchronized(surfaceHolder){
        /*check every creature for the coordinates*/
        Iterator<Sprite> it = creature.iterator();
        while(it.hasNext())
        {
            Sprite current = it.next();
            int sglX = current.getX();
            int sglY = current.getY();
                if(sglX>=x && x<=(sglX+current.getWidth())){
                    if(sglY>=y && y<=(sglY-current.getHeight())){
                        destroy(current);
                        break; //when we found one object, don't iterate no more
                    }
                }

            }
        }
    }

和销毁方法:

 private void destroy(Sprite removed) {
        /*adds the creature clicked to the recicle bin to be destroyed*/
        recicle.add(removedSeagull); //recicle is the other collection
    }

在 Canvas 上绘制生物之前，我将其称为 creature.removeAll(recicle);，这样它就不会与其他迭代器发生冲突。 这是堆栈跟踪:

07-11 21:06:00.905: E/AndroidRuntime(14221): FATAL EXCEPTION: Thread-83
07-11 21:06:00.905: E/AndroidRuntime(14221): java.util.ConcurrentModificationException
07-11 21:06:00.905: E/AndroidRuntime(14221):    at                  java.util.ArrayList$ArrayListIterator.next(ArrayList.java:569)
07-11 21:06:00.905: E/AndroidRuntime(14221):    at   com.example.creatures.GameView$GameThread.drawCreatures(GameView.java:292)
07-11 21:06:00.905: E/AndroidRuntime(14221):    at com.example.creatures.GameView$GameThread.doDraw(GameView.java:283)
07-11 21:06:00.905: E/AndroidRuntime(14221):    at com.example.creatures.GameView$GameThread.run(GameView.java:245)

我想可能是绘图方法，所以可能是那里的错误，在这里:

private void drawCreatures(Canvas c) {
        /*iterate through the array and update all the creatures*/
        synchronized(surfaceHolder){
        Iterator<Sprite> it = creature.iterator();
        while(it.hasNext())
        {
            Sprite current = it.next();
            current.draw(c);
        }
        }
    }

GameThread 的 run 方法在 GameView(它扩展了 surface holder)中调用，如下所示:

 @Override
    public void surfaceCreated(SurfaceHolder arg0) {
        thread.setRunning(true);
        thread.start();
    startTimer(1500);
}

线程的运行方法是这样的:

@Override
    public void run(){
        while(run){
            Canvas c = null;
            try {
                c = surfaceHolder.lockCanvas(null);
                synchronized (surfaceHolder) {
                    if (mode == STATE_RUNNING){
                        doDraw(c);
                    }
                }
            } finally {
                // do this in a finally so that if an exception is thrown
                // during the above, don't leave the Surface in an
                // inconsistent state
                if (c != null) {
                    /*unlocks the canvas and shows the image drawn by the doDraw method*/
                    surfaceHolder.unlockCanvasAndPost(c);
                }

在“doDraw”方法中调用了“drawCreatures”方法。

Answer 1

如果您对迭代器的陈旧结果没问题，那么您可以使用 CopyOnWriteArrayList http://developer.android.com/reference/java/util/concurrent/CopyOnWriteArrayList.html

基本上它确保迭代器显示创建迭代器时存在的内容。唯一的变化是 iterator.remove() 不适用于此列表返回的迭代器。您必须将其从实际列表中删除。

希望对你有帮助，

纳格什