java - 我的圈子不动

Question

我有一些关键事件，而我的角色(一个圆圈)的所有内容都拒绝移动。我已经对此进行了全面搜索并调整了人们的解决方案，但它不起作用。以防万一，我将在这里发布完整的代码，所以请帮忙。

Main.java

package minwoo.main;

import javax.swing.JFrame;

public class Main extends JFrame {

// just to set up the game      
public static void main(String[] args) {

    JFrame start = new JFrame("space game");
    start.setVisible(true);
    start.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    start.setContentPane(new GamePanel());
    start.pack();
    start.setLocationRelativeTo(null);

}

}

GamePanel.java

    package minwoo.main;

    import java.awt.Color;
    import java.awt.Dimension;
    import java.awt.Graphics;
    import java.awt.Graphics2D;
    import java.awt.event.KeyEvent;
    import java.awt.event.KeyListener;
    import java.awt.image.BufferedImage;

    import javax.swing.JPanel;

    public class GamePanel extends JPanel implements Runnable, KeyListener {

// size
public final static int WIDTH = 400;
public final static int HEIGHT = 400;


//player
Player player;

//the loop variables
private Thread thread;
private boolean running = false;

//image
BufferedImage image;
Graphics2D g;

int FPS = 30;
double avFPS;




//the constructor
public GamePanel() {
    addKeyListener(this);
    setPreferredSize(new Dimension(WIDTH,HEIGHT ));
    setFocusable(true);
    requestFocus();

    player = new Player();


}

//functions
public void addNotify() {
    super.addNotify();
    if(thread == null) {
        thread = new Thread(this); // declares the thread.
        thread.start();
    }

}

public void run() {
  running = true;

  image = new BufferedImage(WIDTH,HEIGHT,BufferedImage.TYPE_INT_RGB);
  g = (Graphics2D) image.getGraphics();

  long startTime;
  long waitTime;
  long ms;
  long targetTime = 1000/30; // shows how much is needed to get 30 ticks 

  long frameCount = 0;
  long max_Frame = 30; // maximum amount of frames you are allowed to reach.
  long totalTime = 0;


  while(running) { // start of the game loop
      startTime = System.nanoTime(); // takes note of the current time

      update();
      render();
      draw();


      // System.nanoTime() at this point takes note of current time, which 
      //is different from what it was few nanoseconds ago.
      ms = (System.nanoTime() - startTime) / 1000000;
      // shows how much time has passed, and it is converted to miliseconds.
      waitTime = targetTime - ms;
      /** 
       * let me give you an example.
       * ms is 25 milliseconds, but my target is 30 seconds. To get to
       * that target time, we have to give up 5 seconds. 
       * **/
      if(waitTime < 0) { waitTime = 5; } //sets default if waitTime is
      // negative.

      try {

        Thread.sleep(waitTime);
    } catch (InterruptedException e) {

        e.printStackTrace();
    }

    totalTime += System.nanoTime() - startTime; // accumulates
    // total time it took for the whole process.

    frameCount++; // frame is counted

    if(frameCount == max_Frame) {
        avFPS = 1000.0 / ((totalTime / frameCount) / 1000000);
        frameCount = 0;
        totalTime =0;
    }


  }// end of the game loop


} // end of run()   



@Override
public void keyTyped(KeyEvent e) {

}


private void update() {
    player.update();
} // end of update()

private void render() {

    g.setColor(Color.WHITE);
    g.fillRect(0, 0,WIDTH,HEIGHT);
    g.setColor(Color.BLACK);
    g.drawString("FPS: " + avFPS,150,100);
    player.draw(g);
}// end of render()

@Override
public void keyPressed(KeyEvent e) {
    int Key = e.getKeyCode();
    if(Key == KeyEvent.VK_RIGHT) {
        player.Direction_X(Player.SPEED);
    }
    if(Key == KeyEvent.VK_LEFT) {
        player.Direction_X(Player.SPEED);
    }
    if(Key == KeyEvent.VK_UP) {
        player.Direction_Y(Player.SPEED);
    }
    if(Key == KeyEvent.VK_DOWN) {
        player.Direction_Y(Player.SPEED);
    }

}

@Override
public void keyReleased(KeyEvent e) {
    // TODO Auto-generated method stub
    if(e.getKeyCode() == KeyEvent.VK_RIGHT) {
        player.Direction_X(Player.SPEED);
    }
    if(e.getKeyCode() == KeyEvent.VK_LEFT) {
        player.Direction_X(-Player.SPEED);
    }
    if(e.getKeyCode() == KeyEvent.VK_UP) {
        player.Direction_Y(Player.SPEED);
    }
    if(e.getKeyCode() == KeyEvent.VK_DOWN) {
        player.Direction_Y(-Player.SPEED);
    }

}

//draw()
private void draw() {
    Graphics g2 = this.getGraphics();
    g2.drawImage(image,0,0,null);
    g2.dispose();
}// end of draw()







     }// end of GamePanel class

Player.java

package minwoo.main;
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
public class Player {

//fields
private int x;
private int y;
private int r;

private int dx;
private int dy;
public static final int SPEED = 5;

private int lives; 

private Color character_Color = Color.WHITE;
private Color hit_Color = Color.RED;

// constructor
public Player() {

    x = GamePanel.WIDTH / 2;
    y = GamePanel.HEIGHT / 2;

    r = 5;

    dx = 0;
    dy = 0;




    lives = 3;
} // end of constructor

//movements
public void Direction_X(int speed) {  

    dx = speed;
}


public void Direction_Y(int speed) 
{
    dy = speed;}




//functions
public void update() {

    move();

    //to keep the bounds
    if(x < r) { x = r;}
    if(y < r) {y = r;}
    if(x > GamePanel.WIDTH - r) { x = GamePanel.WIDTH - r; 
    }
    if(y > GamePanel.HEIGHT - r) { y = GamePanel.HEIGHT - r; }

}// end of update()

private void move() {

    x += dx;
    y += dy;

}

public void draw(Graphics2D g) {

    g.setColor(character_Color);
    g.fillOval(dx, dy,2*r,2*r); // circle in the centre.

    g.setStroke(new BasicStroke(3));
    g.setColor(character_Color.darker());
    g.drawOval(dx, dy,2*r,2*r);
    g.setStroke(new BasicStroke(1));

}

}

Answer 1

你的基本问题是你正在绘制增量值而不是位置值......

g.fillOval(dx, dy, 2 * r, 2 * r);
           ^---^---These are the deltas, not the position...

您将/可能遇到的其他问题...

• 使用getGraphics而不是覆盖paintComponent。 getGraphics 可以返回 null，并且您在其上绘制的任何内容都将在下次绘制周期发生时被删除干净。 Swing 使用被动绘画系统，无需您的交互即可触发重绘
• 使用KeyListener。一般来说，您会发现使用 Key Bindings API 更容易它不会遇到与 KeyListener 相同的焦点问题
• 使用线程更新游戏状态时要小心，因为修改状态时可能会发生重绘，最终会得到脏漆。
• 使用“神奇”数字(即GamePanel.WIDTH)。如果我改变窗口的大小，这些值将没有意义。使用经验值，将容器的实际宽度和高度传递给 move 方法
• 您的 keyPressed 和 keyReleased 调用与您的移动代码发生冲突。可以按向左让球向右弹跳...其他方向也是如此，可以让球在朝正确方向移动之前向相反方向弹跳。另一个例子，如果我按住向左，球就会向右移动......

看看

• Performing Custom Painting
• Code Conventions for the Java Programming Language