java - JComboBox 仅在从第 1 到第 2 时更改组件(不是从第 3 到第 2)

Question

所以我尝试寻找解决方案，但一无所获，也不知道如何使我的搜索更准确。我用 Java 做了这个作业，但我被一个 JComboBox 困住了，它并不总是改变我的 JPanel 中的组件。这是我第一次发布问题，如果我搞砸了，很抱歉。无论如何，这就是代码(目的是为一家航空公司创建 GUI)。

问题是，当我从选项 1(“office”)转到选项 2(“Pilot”)时，JComboBox 执行其应该执行的操作并更改 JPanel code> (jplType) 应该如此，但是当我从选项 3(“Host”)返回到选项 2 时，它根本不会更改 JPanel (jplType)。

问题是，我在

中放置了一个 System.out.println()

if(index == 1)
{
  // ..
}

它确实打印了它，但由于某种原因它无法添加JCheckBox。

如果有人能弄清楚我在这里搞砸了什么，我将不胜感激，因为我已经花了一个小时了。

提前致谢。

public class abc {

public static void main(String[] args) {
    CompanyDialog abc = new CompanyDialog();

    }

}

class CompanyDialog extends JFrame {

    private String[] employee = {"office", "Pilot", "Host"};
    private String[] employeeTitles = {"Office options", "Pilot options", "Host options"};
    public final static int GAP = 3;
    // Frame Constants.
    public final static int FWIDTH = 605;
    public final static int FHEIGHT = 235;
    // Constant for the Combo Box.
    public final static int CBWIDTH = FWIDTH/3-4;
    public final static int CBHEIGHT = 20;
    // Width constant for TextField.
    public final static int TWIDTH = 20;

    private JPanel jplType = new JPanel(new FlowLayout(FlowLayout.LEFT, GAP, GAP));

    private JComboBox jcbType = new JComboBox(employee);
    private JLabel jlblOptions = new JLabel();
    private JTextField jtfOptions = new JTextField(TWIDTH);

public CompanyDialog(){
    super("Worker Dialog");

    //Combo box panel configurations
    JPanel jplWorker = new JPanel(new FlowLayout(FlowLayout.LEFT, GAP, GAP));

    JTextField nametxt = new JTextField(TWIDTH);
    jcbType.setPreferredSize(new Dimension(CBWIDTH,CBHEIGHT));
    jplWorker.add(jcbType);

    setDisplay(0);

    add(jplWorker, BorderLayout.NORTH);
    setAlwaysOnTop(true);
    setVisible(true);
    setSize(FWIDTH, FHEIGHT);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setLocationRelativeTo(null);
    setResizable(false);

    jcbType.addItemListener(new ItemListener() { /**Handle item selection*/
        public void itemStateChanged(ItemEvent e) {
            jplType.removeAll();
            setDisplay(jcbType.getSelectedIndex());
        }
    }
            );
}
public void setDisplay(int index){
    jplType.add(jlblOptions);
    jplType.add(jtfOptions);
    jplType.setBorder(new TitledBorder(employeeTitles[index]));
    if(index == 0){
        jlblOptions.setText("Office:");
        jtfOptions.setText("");
    }
    else if(index == 1) {
        jlblOptions.setText("Air Time:");
        jtfOptions.setText("0");
        JCheckBox jcbCaptain = new JCheckBox("Is a Captain");
        jplType.add(jcbCaptain);
    }
    else if(index == 2){
        jlblOptions.setText("Air Time:");
        jtfOptions.setText("0");
    }

    add(jplType, BorderLayout.CENTER);
}
}

Answer 1

更改 setDisplay() 方法

public void setDisplay(int index){
        jplType.add(jlblOptions);
        jplType.add(jtfOptions);
        jplType.setBorder(new TitledBorder(employeeTitles[index]));
        if(index == 0){
            jlblOptions.setText("Office:");
            jtfOptions.setText("");
        }
        else if(index == 1) {
            jlblOptions.setText("Air Time:");
            jtfOptions.setText("0");
            JCheckBox jcbCaptain = new JCheckBox("Is a Captain");
            jplType.add(jcbCaptain);
        }
        else if(index == 2){
            jlblOptions.setText("Air Time:");
            jtfOptions.setText("0");
        } 
        else
        {
            jlblOptions.setText("");
            jtfOptions.setText("");
        }
        add(jplType, BorderLayout.CENTER);

     }

至

public void setDisplay(int index){
        jplType.add(jlblOptions);
        jplType.add(jtfOptions);
        jplType.setBorder(new TitledBorder(employeeTitles[index]));
        if(index == 0){
            jlblOptions.setText("Office:");
            jtfOptions.setText("");
        }
        else if(index == 1) {
            jlblOptions.setText("Air Time:");
            jtfOptions.setText("0");
            JCheckBox jcbCaptain = new JCheckBox("Is a Captain");
            jplType.add(jcbCaptain);
        }
        else if(index == 2){
            jlblOptions.setText("Air Time:");
            jtfOptions.setText("0");
        } 
        else
        {
            jlblOptions.setText("");
            jtfOptions.setText("");
        }
        add(jplType, BorderLayout.CENTER);

        this.revalidate();
    }