Question

我正在制作一个游戏，并且在迭代它时删除/修改数组列表时我读了所有关于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新的集合中以进行删除，但它会移除（有时）对象但是3-4s之后对我来说没什么意义，并且在10-15s之后也给出了并发修改异常。如果有人注意到我的代码中的任何内容，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
                    }
                }

            }
        }
    }

和目标方法：

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

在我在画布上绘制生物之前我称之为creature.removeAll(recicle);，因此它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)

我认为它可能是绘图方法，所以可能是错误，这里是：

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中调用（扩展表面持有者），如下所示：

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

而且线程的run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);
                }

“drawCreatures”方法在“doDraw”方法中调用。

Answer 1

如果您对迭代器的过时结果很好，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（）不能对此列表返回的迭代器起作用。您必须将其从实际列表中删除。

希望有所帮助，

纳格什

Answer 2

为什么您不使用iterator的默认方法？

撰写it.remove()代替destroy(current);

从数组列表中删除对象 - 并发修改例外

2 个答案: