java - 为什么我的屏幕没有变红？

Question

好的，我是编程新手，我正在按照 Youtube 上的教程来构建我自己的游戏。我的问题是我的屏幕没有变红，只是保持灰色。我确定我做错了什么，但在 eclipse 上没有错误。这是代码:

import java.awt.Canvas;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferStrategy;

import javax.swing.JFrame;

public class Game extends Canvas implements Runnable {
    private static final long serialVersionUID = 1L;

    public static int width = 300;
    public static int height = width / 16 * 9;
    public static int scale = 3;

    private Thread thread;
    private JFrame frame;
    private boolean running = false;

    public Game() {
       Dimension size = new Dimension(width * scale, height * scale);
       setPreferredSize(size);

       frame = new JFrame();
    }

    public synchronized void start() {
        running = true;
        thread = new Thread("Display");
        thread.start();

    }

    public synchronized void stop() {
        running = false;
        try {
        thread.join();
        } catch(InterruptedException e) {
            e.printStackTrace();
        }
    }

    public void run() {
        while (running) {
            update();
            render();
        }

    }

    public void update() {

    }

    public void render() {
        BufferStrategy bs = getBufferStrategy();
        if (bs == null) {
            createBufferStrategy(3);
            return;
        }

        Graphics g = bs.getDrawGraphics();
        g.setColor(Color.RED);
        g.fillRect(0, 0, getWidth(), getHeight());
        g.dispose();
        bs.show();
    }

    public static void main(String[] args){
        Game game = new Game();
        game.frame.setResizable(false);
        game.frame.setTitle("JJF");
        game.frame.add(game);
        game.frame.pack();
        game.frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        game.frame.setLocationRelativeTo(null);
        game.frame.setVisible(true);

        game.start();


    }

}

Answer 1

你实际上从来没有为 Thread 提供要运行的东西......

public synchronized void start() {
    running = true;
    // Not the reference to this...
    thread = new Thread(this, "Display");
    thread.start();

}

通过传递 this(它是实现了 Runnable 的 Game 类的一个实例)，Thread将能够调用您的 run 方法

注意:

可视区域的大小应该由组件而不是框架来定义。这可以通过覆盖 getPreferredSize 方法并返回您希望组件达到的首选可视大小来实现。否则，可视区域将是框架的大小减去它的装饰插图，这可能不符合您的期望。

在你的“游戏循环”中，你应该考虑在循环之间有一个小的延迟，以便为系统实际更新屏幕提供时间，这会减轻 Thread 的一些压力

可运行示例

import java.awt.Canvas;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferStrategy;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JFrame;

public class Game extends Canvas implements Runnable {

    private static final long serialVersionUID = 1L;

    public static int width = 300;
    public static int height = width / 16 * 9;
    public static int scale = 3;

    private Thread thread;
    private JFrame frame;
    private boolean running = false;

    public Game() {
        Dimension size = new Dimension(width * scale, height * scale);
        setPreferredSize(size);

        frame = new JFrame();
    }

    public synchronized void start() {
        running = true;
        thread = new Thread(this, "Display");
        thread.start();

    }

    public synchronized void stop() {
        running = false;
        try {
            thread.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    public void run() {
        while (running) {
            update();
            render();
//          try {
//              Thread.sleep(40);
//          } catch (InterruptedException ex) {
//          }
        }

    }

    public void update() {

    }

    public void render() {
        BufferStrategy bs = getBufferStrategy();
        if (bs == null) {
            createBufferStrategy(3);
            return;
        }

        Graphics g = bs.getDrawGraphics();
        g.setColor(Color.RED);
        g.fillRect(0, 0, getWidth(), getHeight());
        g.dispose();
        bs.show();
    }

    public static void main(String[] args) {
        Game game = new Game();
        game.frame.setResizable(false);
        game.frame.setTitle("JJF");
        game.frame.add(game);
        game.frame.pack();
        game.frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        game.frame.setLocationRelativeTo(null);
        game.frame.setVisible(true);

        game.start();

    }

}