CardLayout在用行动Java的变化的“卡”一(CardLayout in Java chan

我正在使用一个简单的游戏JFrame 。我做了一个简单的“启动”屏幕基本上包含一个的String和JButton 。我拿起按钮，点击与actionPerformed(ActionEvent e)的方法。我不知道如何使用点击一个按钮来更改卡。这似乎是一个简单的问题来解决，但扭曲带有这样的：我主要的JFrame，我的启动画面和我的JPanel在游戏发生都是在不同的文件。我的主要文件，Virus.java，是我创建JFrame 。我的文件VirusGamePanel.java是游戏发生。我的文件StartScreen.java与按钮的屏幕。我想改变“卡”的游戏画面当玩家点击按钮。我怎样才能做到这一点？我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:

您只需在您的纠正这一actionPerformed(...)方法：

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（慈禧）她很指出，不会覆盖paint() ，而不是里面做你的画的东西paintComponent(Graphics g)的任何方法JPanel/JComponent 。此外，第一组件添加到您JFrame ，一旦它的尺寸得以实现，那么只有将其设置为可见，而不是之前。相反，设置大小为的JFrame只是覆盖JPanel的方法getPreferredSize()使其返回一些有效的Dimension对象。

不要看这个序列，如您下一次编写代码：

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);
}

这是您的完整的代码：

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));
    }
}