Question

我正在尝试创建一个闪烁的圆圈。我已经到了改变一次然后抛出错误Exception in thread "AWT-EventQueue-0的地步我不知道为什么。你能帮助我吗？这是我的代码：

public class Final {
    private static JPanel contentPane;
    private static int cnt = 0;
    private static int counter =0;
    private static Color[] colours = {
        Color.ORANGE,
        Color.GRAY
    };

    public static void main(String args[]) {
        JFrame frame = new JFrame();
        frame.setSize(400, 525);
        frame.setLocationByPlatform(true);
        frame.setVisible(true);

        ActionListener actListner = new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent event) {
                if (cnt == (colours.length)) {
                    cnt = 0;
                }
                frame.setBackground(colours[cnt++]);
                counter = cnt;
                System.out.println("Counter = "+cnt);
            }
        };

        contentPane = new JPanel() {
            public void paintComponent(Graphics g) {
                super.paintComponent(g);
                g.setColor(colours[counter]);
                g.fillOval(160, 70, 50, 50);
            }
        };

        frame.add(contentPane);

        Timer timer = new Timer(500, actListner);
        timer.start();

    }
}

完整的例外：

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 2
    at Final$2.paintComponent(Final.java:56)
    at javax.swing.JComponent.paint(Unknown Source)
    at javax.swing.JComponent.paintToOffscreen(Unknown Source)
    at javax.swing.RepaintManager$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$4.run(Unknown Source)
    at javax.swing.RepaintManager$4.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$1300(Unknown Source)
    at javax.swing.RepaintManager$ProcessingRunnable.run(Unknown Source)
    at java.awt.event.InvocationEvent.dispatch(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$400(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)

Answer 1

在>检查其边界后，您正在递增计数器，然后使用它。不要这样做，因为这是错误的顺序。首先递增，下一次检查边界并在需要时重置为0，然后才使用它。

// increment first, cnt++;, but not inline as you're doing it cnt++; cnt %= colours.length; // mod it to make it 0 if greater than length myColor = colours[cnt]; // then use it repaint();

Answer 2

只需更改

if (cnt == (colours.length)){

到

if (cnt == (colours.length-1)){

为什么我收到此错误：线程异常＆＃34; AWT-EventQueue-0＆＃34;？

2 个答案: