Java Swing RadioButtons

Question

我正在制作一组单选按钮，中间的一个面板单击单选按钮会改变颜色。

一切看起来都是对的，但是...它不起作用！在主类中，我看到了面板，但颜色没有改变……

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

public class ChoiceFrame extends JFrame 
{
    public ChoiceFrame()
    {

        class ChoiceListener implements ActionListener
        {
            public void actionPerformed(ActionEvent event)
            {
                setTheColor();
            }
        }

        buttonPanel = createButtonPanel();
        add(buttonPanel, BorderLayout.SOUTH);
        colorPanel = createColorPanel();
        add(colorPanel, BorderLayout.NORTH);
        setSize(FRAME_WIDTH, FRAME_HEIGHT);
        colorPanel.repaint();
    }


    public JPanel createButtonPanel()
    {
        JPanel panel = new JPanel();
        panel.setLayout(new GridLayout(3,1));

        redButton = new JRadioButton("Red Colour");
        blueButton = new JRadioButton("Blue Colour");
        greenButton = new JRadioButton("Green Colour");

        redButton.addActionListener(listener);
        blueButton.addActionListener(listener);
        greenButton.addActionListener(listener);

        ButtonGroup group = new ButtonGroup();
        group.add(redButton);
        group.add(blueButton);
        group.add(greenButton);

        panel.add(redButton);
        panel.add(blueButton);
        panel.add(greenButton);

        return panel;
    }

    public JPanel createColorPanel()
    {
        JPanel panel = new JPanel();
        return panel;
    }


    public void setTheColor()
    {
        if (redButton.isSelected())
            colorPanel.setBackground(Color.RED);
        else if (blueButton.isSelected())
            colorPanel.setBackground(Color.BLUE);
        else if (greenButton.isSelected())
            colorPanel.setBackground(Color.GREEN);
    }


    private JPanel colorPanel;
    private JPanel buttonPanel;

    private JRadioButton redButton;
    private JRadioButton blueButton;
    private JRadioButton greenButton;

    private ActionListener listener;

    private static final int FRAME_WIDTH = 400;
    private static final int FRAME_HEIGHT = 400;
}

Answer 1

在你的构造函数中添加ChoiceListener的初始化。listener = new ChoiceListener()

Answer 2

在createButtonPanel()方法中，应该使用以下参数初始化侦听器：

listener = new ChoiceListener();    

当ActionListener字段存在时，创建新的ChoiceListener对象是没有意义的。

Answer 3

您可以创建while循环，每次while循环都会检查选择了哪个radioButton