java - 图像数组在下拉菜单中超出范围

Question

我正在使用 JCombo 框开发一个基本项目，当在框中选择某些内容时，图像会发生变化。窗口和图像显示，但是当我从 JCombo 框中选择第二个图像时，出现数组越界错误。请看一下:

public Dropdown(){
    super("The title");
    setLayout(new FlowLayout());


    box = new JComboBox (filename); //Automatically put the array in a list for us

    box.addItemListener(
            new ItemListener(){ //automatically implements itemlistener
                public void itemStateChanged(ItemEvent event){ //invoked when dropdown menu button is selected
                    if (event.getStateChange() == ItemEvent.SELECTED) //what icon did you select, prevents you from clicking on itself
                        picture.setIcon(firstpictureinarray[box.getSelectedIndex()]); //change it into that selected icon
                }

            }
    );

    add(box);
    picture = new JLabel (firstpictureinarray [0]);
    add(picture);

}
}

这是有问题的行:

picture.setIcon(firstpictureinarray[box.getSelectedIndex()]); //change it into that selected icon

在阅读了很多类似的错误后，我得出的结论是在以下数组中添加这两个元素，但我收到了错误；所以我评论了添加的部分:

private Icon[] firstpictureinarray = {new ImageIcon(getClass().getResource(filename [0] /*, filename [1]*/))}; //code = pics

这是错误:

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 1
at Userinterfaces.Dropdown$1.itemStateChanged(main.java:34)
at javax.swing.JComboBox.fireItemStateChanged(Unknown Source)
at javax.swing.JComboBox.selectedItemChanged(Unknown Source)
at javax.swing.JComboBox.contentsChanged(Unknown Source)
at javax.swing.AbstractListModel.fireContentsChanged(Unknown Source)
at javax.swing.DefaultComboBoxModel.setSelectedItem(Unknown Source)
at javax.swing.JComboBox.setSelectedItem(Unknown Source)
at javax.swing.JComboBox.setSelectedIndex(Unknown Source)
at javax.swing.plaf.basic.BasicComboPopup$Handler.mouseReleased(Unknown Source)
at java.awt.AWTEventMulticaster.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at javax.swing.plaf.basic.BasicComboPopup$1.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(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.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.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)

非常感谢您花时间阅读本文，我非常感谢您为帮助程序员同行所付出的努力!

Answer 1

firstpictureinarray 仅包含单个项目，但您的组合框包含多个项目。

尝试像这样定义和初始化firstpictureinarray，以便数组和组合框始终包含相同数量的项目(即文件数量):

private Icon[] firstpictureinarray = new Icon[filename.length];
for (int i = 0; i < filename.length; i++) {
    firstpictureinarray[i] = new ImageIcon(getClass().getResource(filename [i]));
}

此外，您应该考虑将“firstpictureinarray”重命名为更准确的名称，例如“picturearray”。