使用按钮事件处理程序刷新图像面板

Question

我试图用"刷新"按钮刷新一个图标面板，但无法确定在事件处理程序中放入什么来执行此任务。我只需要执行一次任务的代码（如下）。有人能帮我吗？

import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
public class FourRandomCards extends JFrame {
    JButton jbtRefresh = new JButton("Refresh");
    CardsPanel cardsPanel = new CardsPanel();
    public FourRandomCards() {
    add(cardsPanel, BorderLayout.CENTER);
    add(jbtRefresh, BorderLayout.SOUTH);
//=============================================================
        /** can't figure out what to put in event-handler **/
        jbtRefresh.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
            }
        });
//=============================================================
    }

    public static void main(String[] args) {
        JFrame frame = new FourRandomCards();
        frame.setTitle("Four Random Cards");
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
    private class CardsPanel extends JPanel {
        public CardsPanel() {
            for (int i = 0; i < 4; i++) {
                int card = (int)(Math.random() * 54 + 1);
                ImageIcon cardIcon = new ImageIcon
                ("image/card/" + card + ".png");
                JLabel jlblCard = new JLabel(cardIcon);
                add(jlblCard);
            }
        }
    }
}

Answer 1

基本上，您需要删除所有现有组件并重新添加它们。这意味着您需要一些能够满足此要求的方法。

因为您使用的是局部变量，所以您将无法访问cardsPanel变量，除非您将其设为final或使用类实例变量。。。

public class FourRandomCards extends JFrame {
    JButton jbtRefresh = new JButton("Refresh");
    final CardsPanel cardsPanel = new CardsPanel();
    public FourRandomCards() {
    add(cardsPanel, BorderLayout.CENTER);
    add(jbtRefresh, BorderLayout.SOUTH);
//=============================================================
        /** can't figure out what to put in event-handler **/
        jbtRefresh.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                cardsPanel.refresh();
            }
        });
//=============================================================
    }

    public static void main(String[] args) {
        JFrame frame = new FourRandomCards();
        frame.setTitle("Four Random Cards");
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
    private class CardsPanel extends JPanel {
        public CardsPanel() {
            refresh();
        }
        public void refresh() {
            removeAll();
            for (int i = 0; i < 4; i++) {
                int card = (int)(Math.random() * 54 + 1);
                ImageIcon cardIcon = new ImageIcon
                ("image/card/" + card + ".png");
                JLabel jlblCard = new JLabel(cardIcon);
                add(jlblCard);
            }
            revalidate();
            repaint();
        }
    }
}