在流布局中并排嵌套多个卡片布局

Question

我正在尝试让多个CardLayout并排显示，所有这些都在FlowLayout中。一切运行良好，但窗口中没有任何显示。如何使 FlowLayout 显示 CardLayout 及其组件？

我已经阅读了我能找到的所有相关文档，但发现它们对这个问题没有多大帮助。

这是我的示例代码：

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

@SuppressWarnings("serial")
public class RenderTest extends JPanel{
    private JFrame window;
    private FlowLayout topLevelLayout;
    private Slot[] slots; 
    public static void main(String[] args) {
        RenderTest instance = new RenderTest();
        instance.init();
    }
    private void init(){
        window = new JFrame("Render Test");
        topLevelLayout = new FlowLayout();
        window.setLayout(topLevelLayout);
        window.setResizable(true);
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        window.setLocationRelativeTo(null);
        slots = new Slot[]{new Slot(0), new Slot(2)};
        window.add(slots[0]);
        window.add(slots[1]);
        window.pack();
        window.setVisible(true);
    }
    private class Slot extends JPanel{
        JPanel panel;
        CardLayout cardLayout;
        public Slot(int index){
            RemoveButton remove = new RemoveButton(index);
            AddButton add = new AddButton(index);
            cardLayout = new CardLayout();
            panel = new JPanel();
            panel.setLayout(cardLayout);
            cardLayout.addLayoutComponent(add.getPanel(), "add");
            cardLayout.addLayoutComponent(remove.getPanel(), "show");
            topLevelLayout.addLayoutComponent("card"+index, panel);
        }
        private JPanel getPanel(){
            return this.panel;
        }
        private CardLayout getCardLayout(){
            return this.cardLayout;
        }
    }
    private class AddButton extends JPanel{
        JPanel panel;
        private AddButton(int index){
            panel = new JPanel();
            JButton addButton = new JButton("+");
            addButton.setVerticalTextPosition(AbstractButton.CENTER);
            addButton.setHorizontalTextPosition(AbstractButton.CENTER);
            addButton.setActionCommand("add"+index);
            addButton.addActionListener(new Button());
            panel.add(addButton);
        }
        private JPanel getPanel(){
            return this.panel;
        }
    }
    private class RemoveButton extends JPanel{
        JPanel panel;
        private RemoveButton(int index){
        panel = new JPanel();
        JButton removeButton = new JButton("-");
        removeButton.setVerticalTextPosition(AbstractButton.CENTER);
        removeButton.setHorizontalTextPosition(AbstractButton.CENTER);
        removeButton.setActionCommand("remove"+index);
        removeButton.addActionListener(new Button());
        panel.add(removeButton);
        }
        private JPanel getPanel(){
            return this.panel;
        }
    }
    class Button implements ActionListener{
        public void actionPerformed(ActionEvent e) {
            System.out.println(e.getActionCommand());
            if (e.getActionCommand().equals("add0")){
                slots[0].getCardLayout().show(getParent(), "show");
            }
            if (e.getActionCommand().equals("add1")){
                slots[1].getCardLayout().show(getParent(), "show");
            }
            if (e.getActionCommand().equals("remove0")){
                slots[0].getCardLayout().show(getParent(), "hide");
            }
            if (e.getActionCommand().equals("remove1")){
                slots[1].getCardLayout().show(getParent(), "hide");
            }
        }
    }
}

更新了代码以使用 this 而不是 new JPanel s： https://pastebin.com/e0fhkaen

让它工作：pastebin 5XrFYarD

Answer 1

在Slot类中，不要创建新的JPanel，你应该只使用

this.setLayout(cardLayout);

由于此类扩展了JPanel.

就像现在一样，你只是在框架中添加两个空JPanel。

其他类（AddButton和RemoveButton）也是如此