Question

我尝试打乒乓球但是我的球不动，所以如何让球移动？

这是我的代码

package test;

import java.awt.*;  
import java.awt.event.*;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.*;

public class pingpong1 extends JFrame implements Runnable  {

 public static void main(String[] args) {
        pingpong1 ping = new pingpong1("PingPong Hard Game");

        new Thread(ping).start();

        ping.setSize(600, 300);

        ping.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );

        ping.setVisible(true);

    } private int width, height;  

    private User user;          
    private Computer computer;          
    private Ball ball;
    static int UserScore = 0;
    int ComputerScore=0;

    public pingpong1(String title){

    }
    @Override
    public void paint(Graphics g){
        super.paint(g);
        Image img2;
        ImageIcon img = new ImageIcon("pingpong.png");
        img2 = img.getImage();
        g.drawImage(img2,0,0, this);
        ball.paint(g);
    }
    @Override
    public void run(){
        while(true){
            ball.moveBall();
            repaint();

                try {
                    Thread.sleep(20);
                } catch (InterruptedException e) {
                    Logger.getLogger( getName()).log(Level.SEVERE,null,e);
                }
    }
    }

    public void paintComponent(Graphics g) {
          if (user == null) {
              width = getWidth();
              height = getHeight();
              user = new User();
              computer = new Computer();
              ball = new Ball();
          }
          ball.draw(g);

      } 
    public class User{

    }
    public class Computer{

    }
    public class Ball{
        private int x,y;
        private int centerX , centerY;
        private Color color;
        boolean go;
        Ball(){
            go=false;
        }
        public void paint(Graphics g) {
            // TODO Auto-generated method stub

        }
        public Ball(int x,int y,Color color){
            this.x=x;
            this.y=y;
            this.color=color;
            this.centerX=5;
            this.centerY=5;
        }
        public int getX(){
            return x;
        }
        public int getY(){
            return y;
        }
        public void moveBall(){
            centerX=5;
            x+=centerX;
            y+=centerY;

        } void draw(Graphics g){
            Image img2;
            ImageIcon img = new ImageIcon("pingpong.png");
            img2 = img.getImage();
            g.drawImage(img2, centerX - -35, centerY -10  , null);
        }
    }
    }

Answer 1

首先你的移动代码，需要有一些输入来实际移动球。现在它除了添加x，y并没有做任何事情，并且没有重新绘制它，所以你基本上告诉它什么都不做。如果你正在寻找这样的用户控制的东西会起作用吗？

public void moveIt(KeyEvent evt) {
 switch (evt.getKeyCode()) {
        case KeyEvent.VK_DOWN:
            myY += 5;
            break;
        case KeyEvent.VK_UP:
            myY -= 5;
            break;
        case KeyEvent.VK_LEFT:
            myX -= 5;
            break;
        case KeyEvent.VK_RIGHT:
            myX += 5;
            break;
    } 
}

如果您正在寻找一种自动移动球的方法，那么您需要查看代码中的一些内容。因为你没有考虑速度/方向等...

这是移动球http://introcs.cs.princeton.edu/java/34nbody/Ball.java.html

的基本示例

我会发表评论，但我的代表不到50岁。

Answer 2

在你的代码中，你正确地更新了球在游戏循环中的位置：

class pingpong1

.filter((Q(for_field__is_null=True) | Q(for_field__bool=True))

但你实际上从未在更新的位置重新绘制球：

    while(true){
        ball.moveBall(); // You update movement here
        repaint();
        try {
            Thread.sleep(20);
        } catch (InterruptedException e) {
            System.err.println("Interrupted.");
        }
    }

因为public void paint(Graphics g){ super.paint(g); Image img2; ImageIcon img = new ImageIcon("pingpong.png"); img2 = img.getImage(); g.drawImage(img2,0,0, this); ball.paint(g); // this method is empty }方法ball为空：

班级球

paint

要纠正错误：

public void paint(Graphics g) {
    // TODO Auto-generated method stub
}

或者只是致电public void paint(Graphics g) { ImageIcon icon = new ImageIcon("ball.png"); Image image = icon.getImage(); g.drawImage(image, x, y, null); }，但您仍需要更正ball.draw()和x，因为它们目前是常量，请更改：

要：

g.drawImage(img2, centerX + 35, centerY - 10, null);

如何让代码移动球？

2 个答案: