Java 中的 CardLayout 通过其中一张“卡片"中的动作而改变 [英] CardLayout in Java change by action in one of the 'cards'

问题描述

我正在使用 JFrame 制作一个简单的游戏.我制作了一个简单的开始"屏幕，它基本上由一个 String 和一个 JButton 组成.我正在使用 actionPerformed(ActionEvent e) 方法获取按钮点击.我不知道如何通过单击按钮来更改卡片.这似乎是一个需要解决的简单问题，但随之而来的问题是:我的主 JFrame、我的 StartScreen 和我的 JPanel 都在不同的文件中.我的主文件 Virus.java 是我创建 JFrame 的地方.我的文件 VirusGamePanel.java 是游戏发生的地方.我的文件 StartScreen.java 是带有按钮的屏幕.当玩家单击按钮时，我想将卡片"更改为游戏屏幕.我怎样才能做到这一点?我的 StartScreen.java 文件:

I am making a simple game using a JFrame. I have made a simple "Start" screen which basically consists of a String and a JButton. I am picking up the button click with the actionPerformed(ActionEvent e) method. I don't know how to change the cards using a button click. This may seem like a simple problem to solve, but the twist comes with this: My main JFrame, my StartScreen and my JPanel where the game takes place are all in separate files. My main file, Virus.java, is where I create the JFrame. My file VirusGamePanel.java is where the game takes place. My file StartScreen.java is the screen with the button. I want to change 'cards' to the game screen when the player clicks the button. How can I do this? My StartScreen.java file:

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:

My Virus.java file:

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();

    }

}

推荐答案

您只需在 actionPerformed(...) 方法中纠正此问题:

You simply have to right this in your actionPerformed(...) method :

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 (THE EMPRESS) 本人所指出的那样，不要覆盖 paint() 而是在 paintComponent(Graphics g) 方法中进行绘画任何 JPanel/JComponent.此外，首先将组件添加到您的JFrame，一旦它的大小实现，然后只将其设置为可见，而不是在此之前.无需为 JFrame 设置大小，只需覆盖 JPanel 的方法 getPreferredSize()，使其返回一些有效的 Dimension对象.

As very much pointed out by @kleopatra (THE EMPRESS) herself, don't override paint() instead do your painting stuff inside paintComponent(Graphics g) method of any JPanel/JComponent. Moreover, first add the components to your JFrame, once it's size is realized, then only set it to Visible, not before that. Instead of setting sizes for the JFrame simply override the JPanel's method getPreferredSize(), make it return some valid Dimension Object.

请在下次编写代码时观看此序列:

Do watch this sequence, as you write your code the next time :

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);
}

这是你的完整代码:

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));
    }
}

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