java-JComboBox导致运行时错误

我正在尝试使用Java进行一些GUI开发,并且在添加以下代码时,在初始化类时遇到运行时错误：

public class Search_Album_Main_Tab extends JPanel{
    JComboBox   search_list;
    JTextArea   searched_data;
    JButton     search_button;
    Results_Main_Tab rmt;
    Search_Action_Listener listener;

    public Search_Album_Main_Tab(Results_Main_Tab results_main_tab)
    {
        String[] search_options = {"Album", "Artist", "Genre", "ID", "Year"};
        setLayout(new GridLayout(3,1));
        rmt = results_main_tab;
        listener = new Search_Action_Listener();

        /*  Searched data   */
        searched_data = new JTextArea();

        /*  Search button   */
        search_button = new JButton("Search Album");
        search_button.addActionListener(listener);

        /*  Drop down menu  */
        search_list = new JComboBox(search_options);

        add(search_list);
        add(searched_data);
        add(search_button);     
    }

    private class Search_Action_Listener implements ActionListener
    {

        public void actionPerformed(ActionEvent event) 
        {
            if (event.getSource() == search_button)
            {

            }

        }

    }

}

我得到的错误是：

dcm_gui.GUI at localhost:53806  
    Thread [main] (Suspended (exception NullPointerException))  
        CUIAquaComboBox.applySizeFor(JComponent, CoreUIConstants$Size) line: 454    
        CUIAquaUtilControlSize.applyUISizing(JComponent, CoreUIConstants$Size) line: 99 
        CUIAquaUtilControlSize.access$200(JComponent, CoreUIConstants$Size) line: 13    
        CUIAquaUtilControlSize$PropertySizeListener.applyComponentSize(JComponent, Object) line: 121    
        CUIAquaUtilControlSize.addSizePropertyListener(JComponent) line: 25 
        CUIAquaComboBox.installListeners() line: 47 
        CUIAquaComboBox(BasicComboBoxUI).installUI(JComponent) line: 229    
        CUIAquaComboBox.installUI(JComponent) line: 30  
        JComboBox(JComponent).setUI(ComponentUI) line: 653  
        JComboBox.setUI(ComboBoxUI) line: 238   
        JComboBox.updateUI() line: 247  
        JComboBox.init() line: 212  
        JComboBox.<init>(Object[]) line: 178    
        Search_Album_Main_Tab.<init>(Results_Main_Tab) line: 36 
        GUI.main(String[]) line: 28 
    Daemon Thread [AWT-AppKit] (Running)    
/System/Library/Frameworks/JavaVM.framework/Versions/1.5.0/Home/bin/java (Oct 10, 2010 11:55:27 PM) 

有谁知道为什么吗？

宾雅敏

解决方法:

这看起来像是您自定义外观的问题.使用自定义外观时,我曾经遇到过类似的问题.此处描述：

http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4711700

那是给JFileChooser小部件的,而不是组合框的,但是它可能是相关的.

您应该尝试的第一件事是恢复默认的“金属”外观.如果可行,那么特定的L& F可能有问题.我以前从未使用过CUIAqua L& F,但我认为它是官方的Apple Java L& F.您可能还想尝试将其替换为QuaQua.这是Mac的替代L& F,它可以(取决于实际的错误)避免该问题.

标签：jcombobox,swing,java,user-interface
来源： https://codeday.me/bug/20191209/2096216.html