根据选定的JComboBox更改的JList内容 [英] JList content that changes depending on the selected JComboBox made ​​in

问题描述

我想用Java创建一个由JComboBox和JList组成的GUI.

I would like to create a GUI in Java that is composed of a JComboBox and JList.

从JComboBox {A，B，C}中选择替代项. 根据做出的选择(A，B或C)显示在JList中的不同列表中.

The alternatives are selected from the JComboBox {A, B, C}. Depending on the choice made ​​(A, B, or C) are shown in JList different lists.

示例: 如果我在JComboBox中选择A，则JList将显示以下字符串:A1，A2，A3，A4

example: if I select A in the JComboBox, JList will show the following strings: A1, A2, A3, A4

如果我在JComboBox中选择B，则JList将显示以下字符串:B1，B2，B3，B4

if I select B in the JComboBox, JList will show the following strings: B1, B2, B3, B4

如果我在JComboBox中选择C，则JList将显示以下字符串:C1，C2，C3，C4

if I select C in the JComboBox, JList will show the following strings: C1, C2, C3, C4

我该怎么做?

谢谢

推荐答案

您将ActionListener添加到组合框中.然后，当一个项目被选定则用一个新的ListModel更新JList中.

You add an ActionListener to the combo box. Then when an item is selected you update the JList with a new ListModel.

这里有一个带有两个组合框的示例，但是对于一个组合框和一个JList来说，概念是相同的.

Here is an example with two combo boxes, but the concept would be the same with a combo box and a JList.

import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;

public class ComboBoxTwo extends JPanel implements ActionListener
{
    private JComboBox<String> mainComboBox;
    private JComboBox<String> subComboBox;
    private Hashtable<String, String[]> subItems = new Hashtable<String, String[]>();

    public ComboBoxTwo()
    {
        String[] items = { "Select Item", "Color", "Shape", "Fruit" };
        mainComboBox = new JComboBox<String>( items );
        mainComboBox.addActionListener( this );

        //  prevent action events from being fired when the up/down arrow keys are used
        mainComboBox.putClientProperty("JComboBox.isTableCellEditor", Boolean.TRUE);
        add( mainComboBox );

        //  Create sub combo box with multiple models

        subComboBox = new JComboBox<String>();
        subComboBox.setPrototypeDisplayValue("XXXXXXXXXX"); // JDK1.4
        add( subComboBox );

        String[] subItems1 = { "Select Color", "Red", "Blue", "Green" };
        subItems.put(items[1], subItems1);

        String[] subItems2 = { "Select Shape", "Circle", "Square", "Triangle" };
        subItems.put(items[2], subItems2);

        String[] subItems3 = { "Select Fruit", "Apple", "Orange", "Banana" };
        subItems.put(items[3], subItems3);
    }

    public void actionPerformed(ActionEvent e)
    {
        String item = (String)mainComboBox.getSelectedItem();
        Object o = subItems.get( item );

        if (o == null)
        {
            subComboBox.setModel( new DefaultComboBoxModel() );
        }
        else
        {
            subComboBox.setModel( new DefaultComboBoxModel( (String[])o ) );
        }
    }

    private static void createAndShowUI()
    {
        JFrame frame = new JFrame("SSCCE");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add( new ComboBoxTwo() );
        frame.setLocationByPlatform( true );
        frame.pack();
        frame.setVisible( true );
    }

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

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