java - 删除时出现 ConcurrentModificationException

Question

通常当我看到 ConcurrentModificationException 时，这是由于遍历列表并删除了某些内容。就我而言，我只是引用了列表并试图从中删除一些内容。这是我的代码:

getList(Client.class).remove(client);

这会抛出一个 ConcurrentModificationException。 classToListMap 是这样声明的

private Map<Class, ObservableList> classToListMap;

这里是 getList() 函数:

public <T> List<T> getList(Class T) {
    return classToListMap.get(T);
}

关于为什么这会引发异常有什么想法吗？

下面是抛出异常的完整函数:

private synchronized void deleteClient() {
    DefaultMutableTreeNode node = getRightClickedNode();
    if (node.getUserObject() instanceof Client == false) {
        JOptionPane.showMessageDialog(null, "Please select a client to delete");
        return;
    }
    TreeSelectionListener[] listeners = getTreeSelectionListeners();
    for(TreeSelectionListener listener : listeners){
        removeTreeSelectionListener(listener);
    }
    ((DefaultTreeModel)getModel()).removeNodeFromParent(node);
    Client client = (Client) node.getUserObject();
    applicationContext.getDataRepository().getList(Client.class).remove(client);  //!!!!!!<-- Throws exception
    applicationContext.fireUpdate(new UpdateEvent(UpdateEvent.Type.DELETE, client, new UnknownEvent(this)));
    for(TreeSelectionListener listener : listeners){
        addTreeSelectionListener(listener);
    }
}

这是完整的堆栈跟踪:

Exception in thread "AWT-EventQueue-0" java.util.ConcurrentModificationException
    at java.util.AbstractList$Itr.remove(AbstractList.java:380)
    at java.util.AbstractCollection.remove(AbstractCollection.java:293)
    at com.dvsd.profmetric.ui.gui.client.gui.ClientTree.deleteClient(ClientTree.java:147)
    at com.dvsd.profmetric.ui.gui.client.gui.ClientTree.access$300(ClientTree.java:39)
    at com.dvsd.profmetric.ui.gui.client.gui.ClientTree$3.actionPerformed(ClientTree.java:121)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2346)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
    at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:833)
    at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:877)
    at java.awt.Component.processMouseEvent(Component.java:6527)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
    at java.awt.Component.processEvent(Component.java:6292)
    at java.awt.Container.processEvent(Container.java:2234)
    at java.awt.Component.dispatchEventImpl(Component.java:4883)
    at java.awt.Container.dispatchEventImpl(Container.java:2292)
    at java.awt.Component.dispatchEvent(Component.java:4705)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4898)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4533)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4462)
    at java.awt.Container.dispatchEventImpl(Container.java:2278)
    at java.awt.Window.dispatchEventImpl(Window.java:2739)
    at java.awt.Component.dispatchEvent(Component.java:4705)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:746)
    at java.awt.EventQueue.access$400(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:697)
    at java.awt.EventQueue$3.run(EventQueue.java:691)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86)
    at java.awt.EventQueue$4.run(EventQueue.java:719)
    at java.awt.EventQueue$4.run(EventQueue.java:717)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:716)
    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)

classToListMap 是这样填充的:

private void createClassToListMap() {
        classToListMap = new LinkedHashMap<Class, ObservableList>();

        classToListMap.put(ManagementProfessional.class, managementProfessionalList);
        classToListMap.put(AdministrativeProfessional.class, administrativeProfessionalList);
...

ObservableLists 是 org.jdesktop.observablecollections.ObservableList; 的创建方式如下:

List<ProfitMargin> profitMargins = simulation.getProfitMarginList();
profitMarginList = ObservableCollections.observableList(profitMargins);

其中 ObservableCollections 是一个 org.jdesktop.observablecollections.ObservableCollections;

Answer 1

你没有提供完整的信息，但我猜测 ObservableList 的 Observable 部分意味着列表内容的变化被报告给观察者，并且observer 可能正在遍历列表或尝试在您删除元素时触发的回调中进行自己的修改。如果您需要更多帮助，请发布完整的堆栈跟踪和有关列表观察者回调的信息。