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我已經做了一個小遊戲。現在我想新的粒子添加到播放器每隔10ms：ArrayList中的java.util.ConcurrentModificationException;試圖在繪畫時添加新對象
TimerTask task2 = new TimerTask() {
@Override
public void run() {
if(!_panel.drawing())
new HeatParticle(_panel, _player);
}
};
timer.schedule(task2, 10, 10);
的粒子將自身添加到的GamePanel：
public HeatParticle(GamePanel panel, GameCircle _player) {
_panel = panel;
_particle = new GameCircle(_player.x() + _r.nextInt(10) - 5 + _player.size()/2, _player.y() + _r.nextInt(10) - 5 + _player.size()/2, 5, "draw", Color.RED);
_panel.add(_particle);
startTimer();
}
的的GamePanel店各界一個ArrayList裏面：
private ArrayList<GameCircle> circles = new ArrayList<GameCircle>();
[...]
public void add(GameCircle circle) {
if (!_drawing) {
circles.add(circle);
circle.setIndex(circles.size() - 1);
repaint();
}
}
要繪製所有這些，它用於：
private void draw() {
_drawing = true;
[...]
for (GameCircle circle : circles) {
if (circle != null)
if (circle.drawOrFill() != null)
if (circle.drawOrFill().equals("fill") && circle.draw()) {
_canvas.setColor(circle.color());
_canvas.fillOval(circle.x(), circle.y(), circle.size(), circle.size());
} else if (circle.drawOrFill().equals("draw") && circle.draw()) {
_canvas.setColor(circle.color());
_canvas.drawOval(circle.x(), circle.y(), circle.size(), circle.size());
}
}
_drawing = false;
}
但我得到一個異常：
Exception in thread "AWT-EventQueue-0" java.util.ConcurrentModificationException
at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
at java.util.ArrayList$Itr.next(ArrayList.java:851)
at jakob.GameEngine2D.GamePanel.draw(GamePanel.java:95)
at jakob.GameEngine2D.GamePanel.paint(GamePanel.java:330)
at javax.swing.JComponent.paintToOffscreen(JComponent.java:5210)
at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(RepaintManager.java:1579)
at javax.swing.RepaintManager$PaintManager.paint(RepaintManager.java:1502)
at javax.swing.RepaintManager.paint(RepaintManager.java:1272)
at javax.swing.JComponent._paintImmediately(JComponent.java:5158)
at javax.swing.JComponent.paintImmediately(JComponent.java:4969)
at javax.swing.RepaintManager$4.run(RepaintManager.java:831)
at javax.swing.RepaintManager$4.run(RepaintManager.java:814)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:814)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:789)
at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:738)
at javax.swing.RepaintManager.access$1200(RepaintManager.java:64)
at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1732)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
我認爲這個問題是一個新的社交圈被添加到ArrayList，而其內部的for循環和從來就試圖解決這個問題（布爾_drawing），但它沒有工作。你可以幫我嗎？ -Jakob
當您使用'Iterator'這個數據結構不得更改底層的數據結構，否則你會得到這個'Exception'（一個'foreach'循環使用'背景中的迭代器'）。一個簡單的解決方法是使用普通的'for'循環，但由於併發問題，這可能會跳過一些元素。 – Turing85
好吧，這是最好的答案。我現在使用http://pastebin.com/vXA50Frz，它的工作原理。謝謝！ – Jakob