java - 如何将两个 jComboBox 链接在一起并将数据显示到 jtextarea 中？

Question

我的问题是如何将两个组合框链接在一起。原因是我希望用户能够选择制造商品牌，并让下一个组合框显示与该制造商链接的汽车。然后我希望将数据放入 jtextarea 中以显示给用户。这也适用于我的程序中的 jlists。

package rlc.building.program;
/*
 *
 * @author Jacob
 */
public class GUI extends javax.swing.JFrame {

/**
 * Creates new form GUI
 */
public GUI() {
    initComponents();
}

/**
 * This method is called from within the constructor to initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is always
 * regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    jScrollPane2 = new javax.swing.JScrollPane();
    jList2 = new javax.swing.JList();
    jScrollPane3 = new javax.swing.JScrollPane();
    jTextArea1 = new javax.swing.JTextArea();
    jLabel1 = new javax.swing.JLabel();
    jLabel2 = new javax.swing.JLabel();
    jLabel3 = new javax.swing.JLabel();
    jLabel4 = new javax.swing.JLabel();
    jLabel5 = new javax.swing.JLabel();
    jScrollPane1 = new javax.swing.JScrollPane();
    jList1 = new javax.swing.JList();
    jButton1 = new javax.swing.JButton();
    jComboBox3 = new javax.swing.JComboBox();
    jComboBox4 = new javax.swing.JComboBox();

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    jList2.setModel(new javax.swing.AbstractListModel() {
        String[] strings = { "LED Light Bar £250", "Rally Light Hood Mount £150", "Rally Lights x2 £100", "Limo Tinted Windows £1500", "Custom Exo-Skelton Roll Cage £3000", "Custom Roll-Cage £1000", "Thick White Wall Tires £1450", "Front and Rear Strut Bars £400", " ", " " };
        public int getSize() { return strings.length; }
        public Object getElementAt(int i) { return strings[i]; }
    });
    jScrollPane2.setViewportView(jList2);

    jTextArea1.setColumns(20);
    jTextArea1.setRows(5);
    jScrollPane3.setViewportView(jTextArea1);

    jLabel1.setFont(new java.awt.Font("Arial", 1, 14)); // NOI18N
    jLabel1.setText("Real Life Car Building Program");

    jLabel2.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
    jLabel2.setText("Modifications");
    jLabel2.setToolTipText("This area below is a list of all the modifications you can choose from for any vehicle.");

    jLabel3.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
    jLabel3.setText("Manufacturers");
    jLabel3.setToolTipText("The car companys that you can choose from.");

    jLabel4.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
    jLabel4.setText("Vehicles");
    jLabel4.setToolTipText("The vehicles you can choose from.");

    jLabel5.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
    jLabel5.setText("Parts");
    jLabel5.setToolTipText("The parts that you can install on the vehicle straight from the manufacturer.");

    jList1.setModel(new javax.swing.AbstractListModel() {
        String[] strings = { "Leather Seats £1000", "New Stainless Steel Exhaust £500", "Alloy Wheels £1200", "Checker Plated Steel Panels £400", " " };
        public int getSize() { return strings.length; }
        public Object getElementAt(int i) { return strings[i]; }
    });
    jScrollPane1.setViewportView(jList1);

    jButton1.setFont(new java.awt.Font("Arial", 0, 12)); // NOI18N
    jButton1.setText("Reset");
    jButton1.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jButton1ActionPerformed(evt);
        }
    });

    jComboBox3.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Chevrolet", "Dodge", "Ford", "Honda", "Infiniti", "Land Rover", "Mazda", "Mitsubishi", "Nissan", "Pontiac", "Scion", "Subaru", "Toyota", "Volkswagen" }));
    jComboBox3.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jComboBox3ActionPerformed(evt);
        }
    });

    jComboBox4.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Item 1", "Item 2", "Item 3", "Item 4" }));

    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(208, 208, 208)
            .addComponent(jLabel1)
            .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        .addGroup(layout.createSequentialGroup()
            .addGap(59, 59, 59)
            .addComponent(jLabel3)
            .addGap(163, 163, 163)
            .addComponent(jLabel5)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addComponent(jLabel2)
            .addGap(93, 93, 93))
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
            .addContainerGap()
            .addComponent(jScrollPane3)
            .addGap(18, 18, 18)
            .addComponent(jButton1)
            .addGap(26, 26, 26))
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addContainerGap()
                    .addComponent(jComboBox3, javax.swing.GroupLayout.PREFERRED_SIZE, 173, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGroup(layout.createSequentialGroup()
                    .addContainerGap()
                    .addComponent(jComboBox4, javax.swing.GroupLayout.PREFERRED_SIZE, 173, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGroup(layout.createSequentialGroup()
                    .addGap(71, 71, 71)
                    .addComponent(jLabel4)))
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
            .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 240, Short.MAX_VALUE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
            .addComponent(jScrollPane2, javax.swing.GroupLayout.PREFERRED_SIZE, 241, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addContainerGap())
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 43, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(14, 14, 14)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addComponent(jLabel2, javax.swing.GroupLayout.Alignment.TRAILING)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel5)
                    .addComponent(jLabel3)))
            .addGap(11, 11, 11)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 73, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGroup(layout.createSequentialGroup()
                            .addComponent(jComboBox3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addGap(3, 3, 3)
                            .addComponent(jLabel4)
                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                            .addComponent(jComboBox4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addGroup(layout.createSequentialGroup()
                            .addGap(47, 47, 47)
                            .addComponent(jButton1)
                            .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                        .addGroup(layout.createSequentialGroup()
                            .addGap(18, 18, 18)
                            .addComponent(jScrollPane3, javax.swing.GroupLayout.DEFAULT_SIZE, 129, Short.MAX_VALUE)
                            .addContainerGap())))
                .addGroup(layout.createSequentialGroup()
                    .addComponent(jScrollPane2, javax.swing.GroupLayout.PREFERRED_SIZE, 73, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addGap(0, 0, Short.MAX_VALUE))))
    );

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

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    jTextArea1.setText("");
}                                        

private void jComboBox3ActionPerformed(java.awt.event.ActionEvent evt) {                                           

}                                          

/**
 * @param args the command line arguments
 */




public static void main(String args[]) {
    /* Set the Nimbus look and feel */
    //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
    /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
     * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
     */
    try {
        for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (ClassNotFoundException ex) {
        java.util.logging.Logger.getLogger(GUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(GUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(GUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(GUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>

    /* Create and display the form */

    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new GUI().setVisible(true);
        }
    });



}



// Variables declaration - do not modify                     
private javax.swing.JButton jButton1;
private javax.swing.JComboBox jComboBox3;
private javax.swing.JComboBox jComboBox4;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JLabel jLabel4;
private javax.swing.JLabel jLabel5;
private javax.swing.JList jList1;
private javax.swing.JList jList2;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JScrollPane jScrollPane2;
private javax.swing.JScrollPane jScrollPane3;
private javax.swing.JTextArea jTextArea1;
// End of variables declaration                   
}

该代码适用于我已经构建的 GUI。我只需要填充骨骼即可使程序运行。

Answer 1

The reason being that I want the user to be able to choose a manufacturer brand and for the next combobox to display the cars linked to that manufacturer.

一些提示:

• 创建一个 Manufacturer POJO 类，用于保存制造商的数据以及与其关联的汽车的列表。
• 将 Manufacturer 对象列表添加到第一个组合框模型。
• 根据第一个组合中选择的制造商，获取其关联汽车的列表并填充第二个组合框模型。
• 根据第二个组合框中选择的Car，设置文本区域的文本以显示其数据。

你必须:

• 为两个组合框提供 ItemListener 或 ActionListener。
• 至少为第一个组合框提供自定义ListCellRenderer。

建议读物

• How to Use Combo Boxes
• Handling Events on a Combo Box
• Providing a Custom Renderer
• Combo Box With Custom Renderer (罗布·卡米克)