在Pong中不更新分数

Question

我很困惑为什么我的记分板没有在屏幕上更新。分数在增加(我检查了调试器，球也居中了)。但是记分板根本没有更新，它总是显示"0 : 0“。

Pong类

package com.dheraxysgames.pong;

import java.awt.Dimension;

import javax.swing.JFrame;

public class Pong extends JFrame{

    private static final long serialVersionUID = 1L;

    //Set Resolution
    public static final int width = 300, 
                            height = width / 4 * 3, 
                            scale = 3;

    public Pong() {
        Dimension size = new Dimension(width * scale, height * scale);
        setSize(size);
        setTitle("PONG");
        setResizable(false);
        setVisible(true);
        setLocationRelativeTo(null);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        add(new GamePanel());
    }

    public static int getWindowWidth(){
        return width * scale;
    }

    public static int getWindowHeight(){
        return height * scale;
    }

    public static void main(String[] args) {
        new Pong();
    }

}

GamePanel类

package com.dheraxysgames.pong;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

import javax.swing.JPanel;
import javax.swing.Timer;

public class GamePanel extends JPanel implements ActionListener, KeyListener {

    private static final long serialVersionUID = 1L;

    Ball ball = new Ball();
    Player player = new Player();
    AI ai = new AI(this);

    public GamePanel(){
        Timer time = new Timer(50, this);
        time.start();

        this.addKeyListener(this);
        this.setFocusable(true);
    }

    private void update(){
        player.update();
        ai.update();
        ball.update();

        ball.checkCollision(player);
        ball.checkCollision(ai);
    }

    public void paintComponent(Graphics g){
        super.paintComponent(g);

        g.setColor(Color.BLACK);
        g.fillRect(0, 0, Pong.getWindowWidth(), Pong.getWindowHeight());

        g.setColor(Color.WHITE);
        Font font = new Font("IMMORTAL", Font.BOLD, 50);
        g.setFont(font);
        g.drawString(player.score + " : " + ai.score, Pong.getWindowWidth() / 2 - 60, 50);

        player.paint(g);
        ai.paint(g);
        ball.paint(g);
    }

    public Ball getBall(){
        return ball;
    }

    public void actionPerformed(ActionEvent e) {
        update();
        repaint();
    }

    //Keyboard
    public void keyPressed(KeyEvent e) {
        if (e.getKeyCode() == KeyEvent.VK_UP) player.setYVelocity(-10);
        if (e.getKeyCode() == KeyEvent.VK_DOWN) player.setYVelocity(10);
    }

    public void keyReleased(KeyEvent e) {
        if (e.getKeyCode() == KeyEvent.VK_UP) player.setYVelocity(0);
        if (e.getKeyCode() == KeyEvent.VK_DOWN) player.setYVelocity(0);
    }

    public void keyTyped(KeyEvent e) {

    }

}

Player类

package com.dheraxysgames.pong;

import java.awt.Color;
import java.awt.Graphics;

public class Player {

    public int score = 0;

    private static int width = 50,
                       height = 150;

    private int x = 800, y = (Pong.getWindowHeight() / 2) - (height / 2), 
                yV = 0;

    public Player() {

    }

    public void update(){
        y += yV;
    }

    public void paint(Graphics g){
        g.setColor(Color.GREEN);
        g.fillRect(x, y, width, height);
    }

    public int getX(){
        return x;
    }

    public int getY(){
        return y;
    }

    public int getWidth(){
        return width;
    }

    public int getHeight(){
        return height;
    }

    public void setYVelocity(int speed){
        yV = speed;
    }

}

AI类

package com.dheraxysgames.pong;

import java.awt.Color;
import java.awt.Graphics;

public class AI {

    public int score = 0;

    private static int width = 50,
                       height = 150;

    private GamePanel field;

    private int x = 50, y = (Pong.getWindowHeight() / 2) - (height / 2), 
                yV = 0;

    public AI(GamePanel game) {
        this.field = game;
    }

    public AI(){

    }

    public void update(){
        if(field.getBall().getY() < this.y) yV = -8;
        if(field.getBall().getY() > this.y) yV = 8;
        y += yV;
    }

    public void paint(Graphics g){
        g.setColor(Color.GREEN);
        g.fillRect(x, y, width, height);
    }

    public int getX(){
        return x;
    }

    public int getY(){
        return y;
    }

    public int getWidth(){
        return width;
    }

    public int getHeight(){
        return height;
    }

    public void setYVelocity(int speed){
        yV = speed;
    }

}

Ball类

package com.dheraxysgames.pong;

import java.awt.Color;
import java.awt.Graphics;

public class Ball {

    private int x = Pong.getWindowWidth() / 2, y = Pong.getWindowHeight() / 2, 
                xV = 10, yV = 10;

    private static int size = 40;

    Player player = new Player();
    AI ai = new AI();

    public void update() {
        x += xV;
        y += yV;

        if (x < 0){
            reverseXDirection();
            player.score++;
            x = Pong.getWindowWidth() / 2;
            y = Pong.getWindowHeight() / 2;
        }
        if (x > Pong.getWindowWidth() - size){
            reverseXDirection();
            ai.score++;
            x = Pong.getWindowWidth() / 2;
            y = Pong.getWindowHeight() / 2;
        }
        if (y < 0 || y > Pong.getWindowHeight() - size - 38) reverseYDirection();
    }

    public void paint(Graphics g){
        g.setColor(Color.GREEN);
        g.fillOval(x, y, size, size);
    }

    private void reverseXDirection(){
        xV = -xV;
    }

    private void reverseYDirection(){
        yV = -yV;
    }

    public void checkCollision(Player p) {
        if (this.x + size > p.getX() && this.x + size < p.getX() + p.getWidth()){
            if (this.y + size > p.getY() && this.y + size < p.getY() + p.getHeight()){
                reverseXDirection();
            }
        }
    }

    public void checkCollision(AI ai) {
        if (this.x > ai.getX() && this.x < ai.getX() + ai.getWidth()){
            if (this.y > ai.getY() && this.y < ai.getY() + ai.getHeight()){
                reverseXDirection();
            }
        }
    }

    public int getX(){
        return x;
    }

    public int getY(){
        return y;
    }

}

Answer 1

在您的球类中，您正在更新的分数与在GamePanel类中检查的分数不同。

注意在这两个类中您是如何调用

Player player = new Player();
AI ai = new AI();

Ball中的player和ai是独立于GamePanel中的player和ai的实例。

您需要从GamePanel类获取player和ai，并将它们传递给Ball类。最简单的方法可能是给Ball一个构造函数，如下所示

Player player;
AI ai;
public Ball(Player player, AI ai) {
    this.player = player;
    this.ai = ai;
}

在您的GamePanel类更改中：

Ball ball = new Ball();
Player player = new Player();
AI ai = new AI(this);

要这样做：

Player player = new Player();
AI ai = new AI(this);
Ball ball = new Ball(player, ai);

自从我使用java以来已经有一段时间了，所以我可能忘记了一种更简单的方法来做这件事，但这应该可以解决问题。