Question

我正在尝试使用“刷新”按钮刷新图标面板，但无法弄清楚要在事件处理程序中放置什么来执行此任务。我只需要执行一次任务的代码（下面）。有人可以帮我这个吗？

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。这表明您需要一些能够满足此要求的方法。

因为您正在使用局部变量，所以除非您使用cardsPanel或使用类实例变量，否则您将无法访问final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();
        }
    }
}

使用按钮事件处理程序刷新图像面板

1 个答案: