Question

我的程序中需要三个按钮（最后一个是退出按钮，它已经有效）另外两个按钮需要更改蓝色和红色之间JPanel背景的颜色。

我需要知道AtionListeners中的内容，以便在按下按钮时更改背景颜色。

这是迄今为止的课程：

package myPackageNameGoesHere;

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JPanel;

public class EventPanel extends JPanel {
private static final long serialVersionUID = 123796234;

private JButton blueButton;
private JButton redButton;
private JButton exitButton;

public EventPanel() {
    this.setPreferredSize(new Dimension(200, 300));

    this.blueButton = new JButton("Blue");
    this.add(this.blueButton);

    this.redButton = new JButton("Red");
    this.add(this.redButton);

    this.exitButton = new JButton("Exit");
    this.exitButton.addActionListener(new ExitListener());
    this.add(this.exitButton);
}

private class BlueListener implements ActionListener {
    @Override
    public void actionPerformed(ActionEvent blue) {
        // What goes here?????

    }
}

private class RedListener implements ActionListener {
    @Override
    public void actionPerformed(ActionEvent red) {
        // What goes here????

    }
}
private class ExitListener implements ActionListener {
    @Override
    public void actionPerformed(ActionEvent exit) {
        System.exit(0);
    }
}
}

Answer 1

您不必为每个按钮声明一个侦听器类，您可以使用相同的一个并添加if语句来确定该动作来自哪个按钮。

if (e.getSource() == blueButton) {// e is the ActionEvent
    blueButton.getParent().setBackground(Color.BLUE);
} else if(e.getSource() == redButton) {
    redButton.getParent().setBackground(Color.RED);
}

Answer 2

您可以设置按钮的父组件的背景颜色

Component component = (Component) event.getSource();
component.getParent().setBackground(Color.BLUE);

如何使用JButton更改JPanel的背景颜色？

2 个答案: