动态JComboBoxes

问题描述

我有以下数据（字符串）：

I have following data (String):

Course1: A1
Course1: A2
Course2: B1
Course2: B2
Course2: B3
Course2: B4
Course3: C1
Course3: C2

我想创建两个 JComboBox （JComboBox1，JComboBox2），以便JComboBox1包含Course1，Course2，Course3等。

I'd like to create two JComboBox (JComboBox1, JComboBox2) so that JComboBox1 contains Course1,Course2,Course3, etc.

如果我选择JComboBox1中的Course2，则应在JComboBox2中填充相应的B1，B2，B3，B4。

If I select, say, Course2 from JComboBox1 then corresponding B1,B2,B3,B4 should be populated in JComboBox2.

如何实现这个？非常感谢。

How to implement this? Many Thanks.

推荐答案

是的，只需创建每套，并执行当 JComboBox1 更改时， JComboBox2 上的setModel（）。

Yes, simply create a DefaultComboBoxModel for each set, and do setModel() on JComboBox2 when JComboBox1 changes.

附录：例如，

import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.ComboBoxModel;
import javax.swing.DefaultComboBoxModel;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class ComboTest extends JPanel implements ActionListener, Runnable {

    private final JComboBox combo1 = new JComboBox(
        new String[]{"Course 1", "Course 2", "Course 3"});
    private final JComboBox combo2 = new JComboBox();
    private ComboBoxModel[] models = new ComboBoxModel[3];

    public ComboTest() {
        models[0] = new DefaultComboBoxModel(
            new String[]{"A1", "A2"});
        models[1] = new DefaultComboBoxModel(
            new String[]{"B1", "B2", "B3", "B4"});
        models[2] = new DefaultComboBoxModel(
            new String[]{"C1", "C2"});

        combo2.setModel(models[0]);
        this.add(combo1);
        this.add(combo2);
        combo1.addActionListener(this);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        int i = combo1.getSelectedIndex();
        combo2.setModel(models[i]);
    }

    @Override
    public void run() {
        JFrame f = new JFrame("ComboTest");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(this);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new ComboTest());
    }
}

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