Java swingworker中的并发修改异常

我创建了一个程序来读取串行端口，绘制数据并显示值。我使用SwingWorker来收集、检查和绘制值，同时允许用户停止GUI中的数据收集。我相信当我试图绘制值并显示精确值时，我收到了修改异常

下面是doInBackground（）的简化版本。我删除的行基本上是检查和比较读取的值

protected Integer doInBackground() 
    while (true && !isCancelled()) {
        value = initandReadCOM();
        // I also check and compare the value
        publish(value);
    }
    return 0;
}

然后我使用

process

命令绘制数据。我能找到的关于这个问题的最接近的线程建议使用这个

@Override
protected void process(List<Float> chunks) {
    super.process(chunks);
    float factor = chunks.get(chunks.size() - 1);
    seriesUpdated = getSeries();
    SetDataField(factor);
    this.seriesUpdated.add(new Millisecond(), factor);
}

随着程序运行更长时间，这种异常开始更频繁地出现。我们将非常感谢您的任何帮助

另外，如果您需要其他帮助，请告诉我。谢谢

编辑：下面是stacktrace

Exception in thread "AWT-EventQueue-0" java.util.ConcurrentModificationException
    at java.util.ArrayList$Itr.checkForComodification(Unknown Source)
    at java.util.ArrayList$Itr.next(Unknown Source)
    at java.util.Collections$UnmodifiableCollection$1.next(Unknown Source)
    at org.jfree.chart.plot.XYPlot.drawRangeMarkers(XYPlot.java:4088)
    at org.jfree.chart.plot.XYPlot.draw(XYPlot.java:3281)
    at org.jfree.chart.JFreeChart.draw(JFreeChart.java:1226)
    at org.jfree.chart.ChartPanel.paintComponent(ChartPanel.java:1612)
    at javax.swing.JComponent.paint(Unknown Source)
    at javax.swing.JComponent.paintToOffscreen(Unknown Source)
    at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(Unknown Source)
    at javax.swing.RepaintManager$PaintManager.paint(Unknown Source)
    at javax.swing.RepaintManager.paint(Unknown Source)
    at javax.swing.JComponent._paintImmediately(Unknown Source)
    at javax.swing.JComponent.paintImmediately(Unknown Source)
    at javax.swing.RepaintManager$3.run(Unknown Source)
    at javax.swing.RepaintManager$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source)
    at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source)
    at javax.swing.RepaintManager.prePaintDirtyRegions(Unknown Source)
    at javax.swing.RepaintManager.access$1000(Unknown Source)
    at javax.swing.RepaintManager$ProcessingRunnable.run(Unknown Source)
    at java.awt.event.InvocationEvent.dispatch(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$200(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)

---

您正在修改JFreeChart的数据模型，而它可能会从UI线程中访问该模型以绘制它。要解决此问题，您有不同的选项：

让后台线程独立于

JFreeChart

s模型计算并将结果存储到

Collection

s中。然后在UI线程中更新模型。这是最简单的方法，将图表模型视为UI的一部分，但最终可能仍会在UI线程中完成大量工作

使用多个图表模型。更新与呈现的图表当前使用的图表模型不同的图表模型。然后通过在UI线程内的图表上设置新模型来更新UI。这允许某些特定于图表的计算在后台线程中运行，并且可以通过对当前代码进行最少的更改来实现。但是，如果每次更新时都会重新计算整个图表模型，因此有相当小的增量更改，这可能会导致效率低下

将整个图表代码移到后台线程中。这可能是最彻底的改变，但也是最有效的解决方案。在这个解决方案中，UI线程不再访问图表及其模型（或者只有在确保后台线程不运行的情况下）。相反，整个图表计算和渲染是在后台线程中完成的，并将其放入

缓冲区图像中。UI线程只需将先前渲染的图像点显到屏幕上即可进行绘制。UI和后台线程之间的更新/同步仅由两个图像组成

使用

Lock

或

synchronized

块确保后台和UI线程仅在不同时间访问模型。由于您的后台威胁只包括模型更新，这实际上就像根本没有多线程一样。我只是为了完整性添加了这个选项

---

当您在修改某个数据对象时，另一个数据对象正在读取某个数据对象时，会发生异常。找出问题所在的一种方法是在编辑/读取数据对象的方法中使用

synchronized

关键字。虽然这并不总是解决问题的正确方法，但它至少可以帮助您准确地找出问题发生的地方。你是不是在某个地方迭代你的arraylist然后试图修改它？由于您显示的代码不包括doInBackground中的该部分，因此我将“值”乘以单位转换因子。如果系统无法破译红色的值，我还（忘了提到）有第二次发布。但是如果您是在process（）方法中询问，那么不是，process（）方法是直接从代码中复制的。IYou正在修改JFreeChart的数据模型，而它可能会从UI线程中访问该模型以绘制它。所以冲突是显而易见的。谢谢你的解释。然而，由于我的初学者身份，我不知道如何实施这些建议。是否有一个示例或框架代码，我可以看看？再次感谢您的评论。

Exception in thread "AWT-EventQueue-0" java.util.ConcurrentModificationException
    at java.util.ArrayList$Itr.checkForComodification(Unknown Source)
    at java.util.ArrayList$Itr.next(Unknown Source)
    at java.util.Collections$UnmodifiableCollection$1.next(Unknown Source)
    at org.jfree.chart.plot.XYPlot.drawRangeMarkers(XYPlot.java:4088)
    at org.jfree.chart.plot.XYPlot.draw(XYPlot.java:3281)
    at org.jfree.chart.JFreeChart.draw(JFreeChart.java:1226)
    at org.jfree.chart.ChartPanel.paintComponent(ChartPanel.java:1612)
    at javax.swing.JComponent.paint(Unknown Source)
    at javax.swing.JComponent.paintToOffscreen(Unknown Source)
    at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(Unknown Source)
    at javax.swing.RepaintManager$PaintManager.paint(Unknown Source)
    at javax.swing.RepaintManager.paint(Unknown Source)
    at javax.swing.JComponent._paintImmediately(Unknown Source)
    at javax.swing.JComponent.paintImmediately(Unknown Source)
    at javax.swing.RepaintManager$3.run(Unknown Source)
    at javax.swing.RepaintManager$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source)
    at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source)
    at javax.swing.RepaintManager.prePaintDirtyRegions(Unknown Source)
    at javax.swing.RepaintManager.access$1000(Unknown Source)
    at javax.swing.RepaintManager$ProcessingRunnable.run(Unknown Source)
    at java.awt.event.InvocationEvent.dispatch(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$200(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)