events - JComboBox 焦点和鼠标单击事件不起作用

Question

编辑
Downvoter，这是一个糟糕的问题吗？我提供了该问题的可运行示例代码。如果它对您有用，请告诉我或指出不清楚的地方。

你好，
在下面的代码中有一个 JComboBox在 JFrame ，当鼠标进入JComboBox时我没有得到通知或被点击或获得焦点。然而，PopupMenuEvent工作正常。

我究竟做错了什么？ (我的目标是在 JComboBox 的文本组件被点击时收到警报)

public class TestJComboBox extends javax.swing.JFrame
{
    public TestJComboBox()
    {
        initComponents();
    }

    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        jComboBox1 = new javax.swing.JComboBox();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                formMouseClicked(evt);
            }
        });

        jComboBox1.setEditable(true);
        jComboBox1.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Item 1", "Item 2", "Item 3", "Item 4" }));
        jComboBox1.setName("jComboBox1"); // NOI18N
        jComboBox1.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                jComboBox1MouseClicked(evt);
            }
            public void mouseEntered(java.awt.event.MouseEvent evt) {
                jComboBox1MouseEntered(evt);
            }
        });
        jComboBox1.addPopupMenuListener(new javax.swing.event.PopupMenuListener() {
            public void popupMenuCanceled(javax.swing.event.PopupMenuEvent evt) {
            }
            public void popupMenuWillBecomeInvisible(javax.swing.event.PopupMenuEvent evt) {
            }
            public void popupMenuWillBecomeVisible(javax.swing.event.PopupMenuEvent evt) {
                jComboBox1PopupMenuWillBecomeVisible(evt);
            }
        });
        jComboBox1.addFocusListener(new java.awt.event.FocusAdapter() {
            public void focusGained(java.awt.event.FocusEvent evt) {
                jComboBox1FocusGained(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(70, 70, 70)
                .addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, 226, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(104, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(90, 90, 90)
                .addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, 46, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(164, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>

    private void jComboBox1FocusGained(java.awt.event.FocusEvent evt)
    {
        System.out.println("JComboBox Focus gained");
    }

    private void formMouseClicked(java.awt.event.MouseEvent evt)
    {
        System.out.println("Form clicked");
        jComboBox1.setFocusable(false);
        jComboBox1.setFocusable(true);
    }

    private void jComboBox1MouseClicked(java.awt.event.MouseEvent evt)
    {
        System.out.println("JComboBox Click");
    }

    private void jComboBox1PopupMenuWillBecomeVisible(javax.swing.event.PopupMenuEvent evt)
    {
        System.out.println("JComboBox Visible menu");
    }

    private void jComboBox1MouseEntered(java.awt.event.MouseEvent evt)
    {
        System.out.println("Entered JComboBox");
    }

    public static void main(String args[])
    {
        java.awt.EventQueue.invokeLater(new Runnable()
        {
            public void run()
            {
                new TestJComboBox().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify
    private javax.swing.JComboBox jComboBox1;
    // End of variables declaration
}

谢谢!

Answer 1

可能downvoter 对您使用Netbeans GUI 编辑器感到冒犯。我自己不喜欢它，但如果你发现你实际上可以用它维护一个复杂的 gui，欢迎你使用它。我个人讨厌它，因为各种极其烦人的错误只会在您尝试编辑表单时显示出来，并且它会悄悄地丢失您的布局和组件设置。但这不是重点。

无论如何，你需要像这样添加你的 ActionListener :

jComboBox1.getEditor().getEditorComponent().addMouseListener(...);

JComboBox 实际上是一个复合组件，其中包含 JTextField、JButton 和 JList，因此当鼠标事件真正进入内部 JTextField 时，您将 ActionListener 添加到包装组件。