java - 编写 java 游戏 - JFrame 未按预期工作

Question

我需要一些帮助来定位我在这里犯的错误。我对使用 Swing 还比较陌生，这是我尝试制作的第一个游戏。

问题如下:代码编译正常，但是当我运行此代码时，框架中没有任何显示。我注意到，如果我删除 Player 类中对grabFrame的调用，并取消注释 g.drawRect(...)，则框架中将显示一个矩形，但是当我重新添加grabFrame调用时，再次没有任何显示。

游戏面板:

import java.awt.Dimension;
import javax.swing.JFrame;

public class GamePanel extends JFrame {

    final static int GWIDTH = 512;
    final static int GHEIGHT = 512;
    static final Dimension screenSize = new Dimension(GWIDTH, GHEIGHT);
    JavaGame game;

    public GamePanel () {
        this.setTitle("Game");
        this.setSize(screenSize);
        this.setResizable(false);
        this.setVisible(true);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        game = new JavaGame(screenSize);
        add(game);
    }

    public static void main (String[] args) {   
        GamePanel gp = new GamePanel();
    }
}

Java游戏:

import java.awt.Dimension;
    import java.awt.Graphics;    
    import javax.swing.JPanel;

    class JavaGame extends JPanel {

        // Game variables
        private GameEngine gameEngine;

        public JavaGame(Dimension screenSize) {
            this.setPreferredSize(screenSize);
            gameEngine = new GameEngine();
        }

        @Override
        public void paintComponent(Graphics g) {
            super.paintComponent(g);
            gameEngine.draw(g);
        }
    }

游戏引擎:

import java.awt.Graphics;

public class GameEngine {

    Player p1;
    public GameEngine () {
        p1 = new Player();
    }

    public void draw(Graphics g) {
        drawCharacters(g);
    }

    private void drawCharacters(Graphics g) {
            p1.draw(g);
    }
}

玩家:

import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import javax.imageio.ImageIO;

public class Player {

    private BufferedImage frame;
    private URL frameURL;

    public Player() {
        try {
            frameURL = new File("C:/Users/admin/workspace/JavaGame/src/civ_walk_south.png").toURI().toURL();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }
        grabFrame();

    }

    private void grabFrame() {
            try {
             frame = ImageIO.read(frameURL);

        } catch (IOException e) {
            e.printStackTrace();
        }   
    }

    public void draw(Graphics g) {          
        g.drawImage(frame, 50, 50, null);
        //g.drawRect(50, 50, 50, 50); // put this here for testing, when uncommented it only works if call to grabFrame() is removed from constructor
    }

}

Answer 1

关于:

public GamePanel () {
    this.setTitle("Game");
    this.setSize(screenSize);
    this.setResizable(false);
    this.setVisible(true);  // *****
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    game = new Game(screenSize);
    add(game);
}

添加所有组件之后在 JFrame 上调用 setVisible(true)，而不是之前。

所以，....

public GamePanel () {
    this.setTitle("Game");
    //  this.setSize(screenSize);  // **** don't set sizes like this
    this.setResizable(false);
    // this.setVisible(true);  // *****
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    game = new Game(screenSize);
    add(game);
    pack();  // **** this should size the GUI to the preferred sizes
    setVisible(true); // **** call this here ****
}

<小时/>

另外，你在绘制之前测试过获取到的图像是否为空吗？

这对我来说很有趣，因为您的图像路径似乎位于将包含在 jar 文件内的位置:

frameURL = new File("C:/Users/admin/workspace/JavaGame/src/civ_walk_south.png")
              .toURI().toURL();

为什么不将图像作为资源而不是首先作为文件获取？