JFreeChart抛出java.util.ConcurrentModificationException

Question

我目前正在使用JFreeChat，以便用Java绘制一些图表。实际的绘图是一个相当大的项目的一部分，这不允许我轻松地包含更多的代码。对我来说，这个异常似乎是直接抛出的。

来自JFreeChart组件。如果有人能帮上忙，我将不胜感激。有没有办法更详细地追踪异常抛出的确切位置？我读到，在列表迭代的情况下，通常会抛出异常，同时从同一列表中删除元素(这不是我现在正在做的)。

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 org.jfree.chart.plot.XYPlot.drawAnnotations(XYPlot.java:3972)
    at org.jfree.chart.plot.XYPlot.draw(XYPlot.java:3339)
    at org.jfree.chart.JFreeChart.draw(JFreeChart.java:1229)
    at org.jfree.chart.ChartPanel.paintComponent(ChartPanel.java:1624)
    at javax.swing.JComponent.paint(JComponent.java:1056)
    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.BufferStrategyPaintManager.paint(BufferStrategyPaintManager.java:306)
    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:80)
    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:80)
    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)

诚挚的问候。

Answer 1

版本1.0.19中第3972行的drawAnnotations()源代码显示为here；它没有什么特别之处，功能正常。如果无意中使顶级容器可见或更新了initial thread上的绘图数据集，则可能会出现问题。所产生的更新事件将在event dispatch thread上执行，可能会导致争用情况。Swing要求您仅在event dispatch thread上构造和操作Swing GUI对象。如果错误代码不明显，请尝试here所示的方法来检测潜在的违规。

Answer 2

• 您使用的是哪个版本？
• 在jfreechart代码中，它只迭代了jfreechart

我会说你有另一个线程正在修改注释列表。如果您可以在IDE中重现这种情况，则在抛出此异常时设置断点(挂起vm中的所有线程)，并在发生异常时检查其他线程。

请参阅Eclipse Conditional-Breakpoint. How to check if exception occurs?

Answer 3

请参阅此问题：

How to avoid "ConcurrentModificationException" while removing elements from ArrayList while iterating it?

这里的问题是类似的；堆栈跟踪中的ArrayList正在被并发地操作。上面的问题与删除元素有关，但多个线程的任何并发操作都会导致此问题。ArrayList不是线程安全的。

另一个值得关注的问题是：How do I make my ArrayList Thread-Safe? Another approach to problem in Java?

如果这不是您的ArrayList，那么它可能是您正在调用的任何代码中的错误。