Question

所以我是Java的新手，我的突破游戏需要一些帮助。我的JFrame只是空白，我不知道如何解决？

所以我有一个球类，一个桨类，一个帆布类，一个砖类以及一个主类。在我的画布课程中，我设置了球，桨和砖具有的所有功能。在砖课程中，我绘制了砖。在我的主要工作中，我JFrame是空白

主类：

public class Main {
    public static void main(String[] args){
        JFrame frame = new JFrame();
        Canvas c = new Canvas();

        frame.add(c);
        frame.pack();
        frame.setResizable(false);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

我希望JFrame会显示游戏，而不仅仅是空白窗口

package breakout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.image.BufferedImage;
import java.util.ArrayList;
import javax.swing.JPanel;
import javax.swing.Timer;

import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Toolkit;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.event.KeyEvent;


import breakout.Bricks.Type;

public class Canvas extends JPanel implements ActionListener, MouseMotionListener, MouseListener, KeyListener {
    /**
     * 
     */
        private static final long serialVersionUID = 1L;
        private static final int HEIGHT = 600;
        public static final int WIDTH = 720;

        private int horizontalCount;
        private BufferedImage image;
        private Graphics2D bufferedGraphics;
        private Timer time;
        private static final Font endFont = new Font(Font.SANS_SERIF, Font.BOLD, 20);
        private static final Font scoreFont = new Font(Font.SANS_SERIF, Font.BOLD, 15);

        private Paddle player;
        private Ball ball;
        ArrayList<ArrayList<Bricks>> bricks;


    public Canvas() {
        super();
        setPreferredSize( new Dimension(WIDTH, HEIGHT));
        image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
        bufferedGraphics = image.createGraphics();
        time = new Timer (15, this);
        player = new Paddle((WIDTH/2)-(Paddle.PADDLE_WIDTH/2));
        ball = new Ball (((player.getX() + (Paddle.PADDLE_WIDTH / 2 )) - (Ball.DIAMETER / 2)), (Paddle.Y_POS - (Ball.DIAMETER + 10 )), -5, -5);

        bricks = new ArrayList<ArrayList<Bricks>>();
        horizontalCount = WIDTH / Bricks.BRICK_WIDTH;
        for(int i = 0; i < 8; ++i) {
            ArrayList<Bricks> temp = new ArrayList<Bricks>();
            @SuppressWarnings("unused")
            Type rowColor = null;
            switch(i) {
            case 0 :
            case 2:
                rowColor = Type.LOW;
                break;
            case 1 :
            case 3 :
            case 5 :
                rowColor = Type.MEDIUM;
                break;
            case 4 :
            case 6 :
                rowColor = Type.HIGH;
                break;
            case 7 :
                default :
                    rowColor = Type.ULTRA;
                    break;

            }
            for(int j = 0; j < horizontalCount; ++j) {
                Bricks tempBrick = new Bricks();
                temp.add(tempBrick);
            }
            bricks.add(temp);
            addMouseMotionListener(this);
            addMouseListener(this);
            addKeyListener(this);
            requestFocus();

        }
    }

    public void actionPerformed(ActionEvent e) {
        checkCollisions();
        ball.Move();
        for(int i = 0; i < bricks.size(); ++i) {
            ArrayList<Bricks> al = bricks.get(i);
            for(int j = 0; j < al.size(); ++j) {
                Bricks b = al.get(j);
                if(b.dead()) {
                    al.remove(b);

                }
            }
        }
        repaint();
    }

    private void checkCollisions() {
        if(player.hitPaddle(ball)) {
            ball.setDY(ball.getDY() * -1);
            return;
        }
        if(ball.getX() >= (WIDTH - Ball.DIAMETER) || ball.getX() <= 0) {
            ball.setDX(ball.getDX() * -1);
        }
        if(ball.getY() > (Paddle.Y_POS + Paddle.PADDLE_HEIGHT + 10)) {
            resetBall();
        }
        if(ball.getY() <= 0) {
            ball.setDY(ball.getDY() * -1);
        }
        int brickRowActive = 0;
        for(ArrayList<Bricks> alb : bricks) {
            if(alb.size() == horizontalCount) {
                ++brickRowActive;
            }
        }

        for(int i = (brickRowActive==0) ? 0 : (brickRowActive - 1); i < bricks.size(); ++i) {
            for(Bricks b : bricks.get(i)) {
                if(b.hitBy(ball)) {
                    player.setScore(player.getScore() + b.getBrickType().getPoints());
                    b.decrementType();
                }
            }
        }
    }

    private void resetBall() {
        if(gameOver()) {
            time.stop();
            return;
        }
        ball.setX(WIDTH/2);
        ball.setDY((HEIGHT/2) + 80);
        player.setLives(player.getLives() -1);
        player.setScore(player.getScore() <= 1);

    }

    private boolean gameOver() {
        if(player.getLives() <= 1) {
            return true;
        }
        return false; 
    }


    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        bufferedGraphics.clearRect(0, 0, WIDTH, HEIGHT);
        player.drawPaddle(bufferedGraphics);
        player.drawBall(bufferedGraphics);
        for(ArrayList<Bricks> row : bricks) {
        for(Bricks b : row) {
            b.drawBrick(bufferedGraphics);
        }
        }

        bufferedGraphics.setFont(scoreFont);
        bufferedGraphics.drawString("Score: " + player.getScore(), 10, 25);
        if(gameOver() && ball.getY() >= HEIGHT) {
            bufferedGraphics.setColor(Color.black);
            bufferedGraphics.setFont(endFont);
            bufferedGraphics.drawString("Game Over Score: " + player.getScore(), (WIDTH /2) -85, (HEIGHT/2));

        }
        if(empty()) {
            bufferedGraphics.setColor(Color.black);
            bufferedGraphics.setFont(endFont);
            bufferedGraphics.drawString("You won. Score: " + player.getScore(), (WIDTH /2) -85, (HEIGHT /2));
            time.stop();
        }
        g.drawImage(image, 0, 0, this);
        Toolkit.getDefaultToolkit().sync();
    }

    private boolean empty() {
        for(ArrayList<Bricks> al : bricks) {
            if(al.size() != 0) {
                return false;
            }
        }
        return true;
    }


    @Override
    public void mouseMoved(MouseEvent e) {
        player.setX(e.getX() - (Paddle.PADDLE_WIDTH / 2));
    }

    @Override
    public void mouseClicked(MouseEvent e) {
        if(time.isRunning()) {
            return;
        }
        time.start();
    }
    @Override
    public void mouseDragged(MouseEvent e) { }

    @Override
    public void mouseEntered(MouseEvent arg0) {}

    @Override
    public void mouseExited(MouseEvent arg0) {}

    @Override
    public void mousePressed(MouseEvent arg0) {}

    @Override
    public void mouseReleased(MouseEvent arg0) {}

    @Override
    public void keyPressed(KeyEvent arg0) {}

    @Override
    public void keyReleased(KeyEvent arg0) {}

    @Override
    public void keyTyped(KeyEvent arg0) {}  
}

Answer 1

按照SO的要求准备MCVE，不仅使帮助变得更加容易。
在许多情况下，准备一个时，您可能会发现问题，因此它是一个很好的调试工具。
回答“为什么我的JFrame为空白？”您可以创建如下所示的最小代码示例（将整个代码复制并粘贴到GameBoard.java中并运行）：

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.util.ArrayList;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class GameBoard extends JPanel {

        static final int HEIGHT = 600, WIDTH = 720, BRICK_ROWS = 8;
        private final int horizontalCount;
        private static final Font scoreFont = new Font(Font.SANS_SERIF, Font.BOLD, 15);
        private final Paddle player;
        private final Ball ball;
        ArrayList<ArrayList<Brick>> bricks;

    public GameBoard() {
        super();
        setPreferredSize( new Dimension(WIDTH, HEIGHT));

        player = new Paddle(WIDTH/2-Paddle.PADDLE_WIDTH/2);
        ball = new Ball (player.getX() + Paddle.PADDLE_WIDTH / 2 - Ball.DIAMETER / 2,
                                                        Paddle.Y_POS - (Ball.DIAMETER + 10 ));
        bricks = new ArrayList<>();
        horizontalCount = WIDTH / Brick.BRICK_WIDTH;
        for(int i = 0; i < BRICK_ROWS; ++i) {

            ArrayList<Brick> temp = new ArrayList<>();
            for(int j = 0; j < horizontalCount; ++j) {
                Brick tempBrick = new Brick(j*Brick.BRICK_WIDTH , Brick.BRICK_YPOS + i*Brick.BRICK_HEIGHT);
                temp.add(tempBrick);
            }
            bricks.add(temp);
        }
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2D = (Graphics2D)g;
        g2D.clearRect(0, 0, WIDTH, HEIGHT);
        player.drawPaddle(g2D);
        ball.drawBall(g2D);
        for(ArrayList<Brick> row : bricks) {
            for(Brick b : row) {
                b.drawBrick(g2D);
            }
        }
        g2D.setFont(scoreFont);
        g2D.drawString("Score: " + player.getScore(), 10, 25);
    }
}

class Paddle{

    public final static int PADDLE_WIDTH = 100, PADDLE_HEIGHT= 30, Y_POS = GameBoard.HEIGHT - 2* PADDLE_HEIGHT;
    private int xPos, score;

    Paddle(int xPos) {
        this.xPos = xPos;
    }

    void setX(int xPos) {this.xPos = xPos;}

    int getX() {return xPos;}

    String getScore() {
        return String.valueOf(score);
    }

    void drawPaddle(Graphics2D g2D) {
        g2D.setColor(Color.GREEN);
        g2D.fillRect(xPos, Y_POS, PADDLE_WIDTH, PADDLE_HEIGHT);
    }

    public static void main(String[] args) {

        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocation(400,250);
        frame.add(new GameBoard());
        frame.pack();
        frame.setResizable(false);
        frame.setVisible(true);
    }
}

class Brick{

    final static int BRICK_WIDTH = 80, BRICK_HEIGHT = 15, BRICK_YPOS = 50;
    int xPos, yPos;

    Brick(int xPos, int yPos) {
        this.xPos = xPos;
        this.yPos = yPos;
    }

    void drawBrick(Graphics2D g2D) {
        g2D.setColor(Color.RED);
        g2D.fillRect(xPos, yPos, BRICK_WIDTH, BRICK_HEIGHT);
        g2D.setColor(Color.BLACK);
        g2D.drawRect(xPos, yPos, BRICK_WIDTH, BRICK_HEIGHT);
    }
}

class Ball{

    final static int DIAMETER = 40;
    int xPos, yPos;

    Ball(int xPos, int yPos) {
        this.xPos = xPos;
        this.yPos = yPos;
    }

    void drawBall(Graphics2D g2D) {
        g2D.setColor(Color.BLUE);
        g2D.fillOval(xPos, yPos, DIAMETER, DIAMETER);
    }
}

这将产生以下结果，我相信这可以作为您要实现的目标的基础：

现在开始添加缺少的功能，看看有什么不好的功能。

Answer 2

我也很新，所以我不确定它为什么对我有用，但是我使用Canvas c = new yourClass();，以及在要从中调用它的类上使用extends canvas

为什么我的突破游戏中的JFrame空白？

2 个答案: