1

嗨，当我尝试从 JPanel 中实现 State 接口的列表中删除一个元素时，我遇到了这个奇怪的异常。这是代码：

public static class ButtonListener implements ActionListener {
    private State state;

    public ButtonListener(State state) {
        this.state = state;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        state.applyMove(state.getMoves().get(0));
    }
}

而 JPanel 是“applyMove”方法的实现：

public class RushHourBoard extends JPanel implements MouseListener, MouseMotionListener, State {
...
private List<Vehicle> vehicles;
...

@Override
public State applyMove(Move vehicleMove) {
    VehicleMove move = (VehicleMove) vehicleMove;
    Vehicle moved = move.getVehicle();
    vehicles.remove(moved);
    ...

以及异常的痕迹：

Exception in thread "AWT-EventQueue-0" java.lang.UnsupportedOperationException
at java.util.AbstractList.remove(AbstractList.java:161)
at entrery.rushhour.RushHourBoard.applyMove(RushHourBoard.java:174)
at entrery.rushhour.MyDragDemo$ButtonListener.actionPerformed(MyDragDemo.java:59)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6504)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6269)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4860)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4686)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
at java.awt.Container.dispatchEventImpl(Container.java:2273)
at java.awt.Window.dispatchEventImpl(Window.java:2713)
at java.awt.Component.dispatchEvent(Component.java:4686)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707)
at java.awt.EventQueue.access$000(EventQueue.java:101)
at java.awt.EventQueue$3.run(EventQueue.java:666)
at java.awt.EventQueue$3.run(EventQueue.java:664)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.awt.EventQueue$4.run(EventQueue.java:680)
at java.awt.EventQueue$4.run(EventQueue.java:678)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:677)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

这与 UI 线程安全策略有关吗？提前感谢您的帮助。

4

1 回答 1

2

分配给的实例RushHourBoard.vehicles不支持删除。也许它来自Arrays.asList或Collections.unmodifiableList。

List，就像Java集合中的许多一样，是一个糟糕的接口。它是如此不具体，许多方法可能无法实现（有用）。即使有一个松散的契约，许多集合实现甚至不符合它们实现的接口的最小条款。

于 2013-01-12T14:57:39.540 回答