Java中的CardLayout通过“卡片”之一中的操作进行更改

Question

我正在使用制作一个简单的游戏JFrame。我制作了一个简单的“开始”屏幕，该屏幕主要由a
String和a组成JButton。我正在使用该actionPerformed(ActionEvent e)方法单击按钮。我不知道如何通过单击按钮来更改卡。这看起来似乎是一个很简单的问题，但随之而来的是：游戏的主JFrame，StartScreen和JPanel都位于单独的文件中。我的主文件Virus.java是创建该文件的位置JFrame。我的文件VirusGamePanel.java是进行游戏的地方。我的文件StartScreen.java是带有按钮的屏幕。当玩家单击按钮时，我想将“纸牌”更改为游戏屏幕。我怎样才能做到这一点？我的StartScreen.java文件：

package virus;

import javax.swing.JPanel;
import java.awt.event.ActionListener;
import java.awt.Graphics;
import java.awt.Font;
import java.awt.Color;
import javax.swing.JButton;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.CardLayout;




public class StartScreen extends JPanel implements ActionListener{
    private static final long serialVersionUID = 1L;
    JButton start = new JButton("Start");
    public StartScreen(){
        start.addActionListener(this);
        start.setBounds(new Rectangle(400,300,100,30));
        this.add(start);
    }
    public void paint(Graphics g){
        super.paint(g);
        g.setFont(new Font("Impact",Font.BOLD,72));
        g.setColor(Color.MAGENTA);
        g.drawString("Virus",275,300);
    }
    public void actionPerformed(ActionEvent e)
    {
        if(e.getSource()==start)
        {
            //what to do here?
        }
    }
}

我的Virus.java文件：

package virus;

import javax.swing.*;
import java.awt.CardLayout;
import virus.StartScreen;

public class Virus extends JFrame{
    private static final long serialVersionUID =1L;
    JFrame jf = new JFrame("Virus");
    static JPanel thegame = new JPanel(new CardLayout());
    JPanel game = new VirusGamePanel();
    JPanel start = new StartScreen();

    public Virus(){
        jf.setResizable(false);
        jf.setSize(600,600);
        jf.setLocationRelativeTo(null);
        jf.setDefaultCloseOperation(EXIT_ON_CLOSE);
        jf.setVisible(true);
        jf.add(thegame);
        thegame.add(start);
        thegame.add(game);

    }

    public static void main(String[] args) {
        new Virus();

    }

}

Answer 1

您只需在您的actionPerformed(...)方法中对此进行纠正：

public void actionPerformed(ActionEvent e)
{
    if(e.getSource()==start)
    {
        //what to do here?
        CardLayout cardLayout = (CardLayout) Virus.thegame.getLayout();
        cardLayout.next(Virus.thegame);
    }
}

正如@kleopatra（皇后乐队）本人所指出的那样，请不要替代paint()您在paintComponent(Graphics g)any方法中的绘画内容JPanel/JComponent。而且，JFrame一旦实现大小，首先将组件添加到您的中，然后仅将其设置为Visible，而不是在此之前。而不是为JFrame简单地覆盖JPanel的方法设置大小，而是getPreferredSize()使其返回一些有效的DimensionObject。

下次观看代码时，请注意以下顺序：

public Virus(){
    jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    jf.setResizable(false);                               
    thegame.add(start);
    thegame.add(game);
    jf.add(thegame);        
    jf.pack();
    jf.setLocationRelativeTo(null);
    jf.setVisible(true);
}

这是您的完整代码：

import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.event.ActionListener;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Font;
import java.awt.Color;
import javax.swing.JButton;
import javax.swing.JLabel;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.CardLayout;

public class Virus extends JFrame{
    private static final long serialVersionUID =1L;
    JFrame jf = new JFrame("Virus");
    static JPanel thegame = new JPanel(new CardLayout());
    JPanel game = new VirusGamePanel();
    JPanel start = new StartScreen();

    public Virus(){
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        jf.setResizable(false);                               
        thegame.add(start);
        thegame.add(game);
        jf.add(thegame);        
        jf.pack();
        jf.setLocationRelativeTo(null);
        jf.setVisible(true);
    }

    public static void main(String[] args) {
        new Virus();

    }

}

class StartScreen extends JPanel implements ActionListener{
    private static final long serialVersionUID = 1L;
    JButton start = new JButton("Start");
    public StartScreen(){
        start.addActionListener(this);
        start.setBounds(new Rectangle(400,300,100,30));
        this.add(start);
    }

    @Override
    protected void paintComponent(Graphics g){
        super.paintComponent(g);
        g.setFont(new Font("Impact",Font.BOLD,72));
        g.setColor(Color.MAGENTA);
        g.drawString("Virus",275,300);
    }

    @Override
    public Dimension getPreferredSize()
    {
        return (new Dimension(600, 600));
    }

    public void actionPerformed(ActionEvent e)
    {
        if(e.getSource()==start)
        {
            //what to do here?
            CardLayout cardLayout = (CardLayout) Virus.thegame.getLayout();
            cardLayout.next(Virus.thegame);
        }
    }
}

class VirusGamePanel extends JPanel
{
    public VirusGamePanel()
    {
        JLabel label = new JLabel("I am ON", JLabel.CENTER);
        add(label);
    }

    @Override
    public Dimension getPreferredSize()
    {
        return (new Dimension(600, 600));
    }
}