我如何刪除，改變顏色，並在java中改變球的類型

Question

幫我找到一個代碼來改變顏色，改變球的類型，並從畫布上移除球..我嘗試了很多次，但總是錯誤..

package bouncetugas; 

import java.awt.*; 
import java.awt.event.*; 
import javax.swing.*; 

public class BounceTugas { 

public static void main(String[] args) { 

    EventQueue.invokeLater(new Runnable() 
      { 
       public void run() 
       { 
        JFrame frame = new BounceFrame(); 
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
        frame.setVisible(true); 
       } 
      }); 
    } 
} 
/** A runnable animate a bouncing ball*/ 

class BallRunnable implements Runnable 
{ 


public BallRunnable(Ball aBall, Component aComponent) 
{ 
    ball = aBall; 
    component = aComponent; 
} 

public void run() 
{ 

    try { 

     for (int i = 1; i <= STEPS; i++) 
     { 
      ball.move(component.getBounds()); 
      component.repaint(); 
      Thread.sleep(DELAY); 
     } 
    } 
    catch (InterruptedException e) 
    { 
    } 
} 

private Ball ball; 
private Component component; 
public static final int STEPS = 1000; 
public static final int DELAY = 5; 
} 

//The frame with panel and buttons. 

class BounceFrame extends JFrame 
{ 

/*Constructs the frame with the component for showing 
the bouncing ball and Start and Close buttons*/ 
public BounceFrame() 
{ 
    setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT); 
    setTitle("Bounce Latihan"); 

    comp = new BallComponent(); 
    add(comp, BorderLayout.CENTER); 
    JPanel buttonPanel = new JPanel(); 
    addButton(buttonPanel, "Add Ball", new ActionListener() 
    { 
     public void actionPerformed(ActionEvent event) 
     { 
      addBall(); 
     } 
    }); 

     addButton(buttonPanel, "Remove Ball", new ActionListener() 
    { 
     public void actionPerformed(ActionEvent event) 
     { 
      removeBall(); 
     } 
    }); 

     addButton(buttonPanel, "Change Color", new ActionListener() 
    { 
     public void actionPerformed(ActionEvent event) 
     { 
      changeColor(); 
     } 
    }); 
     addButton(buttonPanel, "Change Type", new ActionListener() 
    { 
     public void actionPerformed(ActionEvent event) 
     { 
      changeBall(); 
     } 
    }); 
      addButton(buttonPanel, "Start", new ActionListener() 
    { 
     public void actionPerformed(ActionEvent event) 
     { 
      startBall(); 
     } 
    }); 

     addButton(buttonPanel, "Pause", new ActionListener() 
    { 
     public void actionPerformed(ActionEvent event) 
     { 
      pauseBall(); 
     } 
    }); 

     addButton(buttonPanel, "Close", new ActionListener() 
    { 
     public void actionPerformed(ActionEvent event) 
     { 
      System.exit(0); 
     } 
    }); 
    add(buttonPanel, BorderLayout.SOUTH); 
} 

//Adds a button to a container. 
public void addButton(Container c, String title, ActionListener listener) 
{ 
    JButton button = new JButton(title); 
    c.add(button); 
    button.addActionListener(listener); 
} 

//Adds a bouncing ball to the canvas and starts a thread to make it bounce 
public void addBall() 
{ 
    Ball b = new Ball(); 
    comp.add(b); 
    Runnable r = new BallRunnable(b, comp); 
    Thread t = new Thread(r); 
    t.start(); 
} 

public void removeBall() 
{ 
    //Ball.remove(Ball.size() - 1);  
} 

public void changeColor() 
{ 
    if (g2.getColor() = Color.RED){ 
      .g2.setColor(Color.GREEN); 
     } 
     else{ 
      g2.setColor(Color.RED); 
     } 

     this.repaint(); 
} 

public void startBall() 
{ 
    Thread r = new Thread(); 
    r.start(); 
    synchronized(r) { 
     r.notify(); 
    } 
} 

public void pauseBall() { 
    synchronized (this) { 
    try { 
    wait(); 
    } catch (InterruptedException e) { 
    } 
    } 
} 

private BallComponent comp; 
public static final int DEFAULT_WIDTH = 650; 
public static final int DEFAULT_HEIGHT = 450; 
public static final int STEPS = 1000; 
public static final int DELAY = 3; 
} 

類球

import java.awt.geom.*; 

class Ball { 


//Moves the ball to the next position, 
//reversing direction if it hits one of the edges 
public void move(Rectangle2D bounds) 
    { 
     x += dx; 
     y += dy; 
     if (x < bounds.getMinX()) 
     { 
      x = bounds.getMinX(); 
      dx = -dx; 
     } 
     if (x + XSIZE >= bounds.getMaxX()) 
     { 
      x = bounds.getMaxX() - XSIZE; 
      dx = -dx; 
     } 
     if (y < bounds.getMinY()) 
     { 
      y = bounds.getMinY(); 
      dy = -dy; 
     } 
     if (y + YSIZE >= bounds.getMaxY()) 
     { 
      y = bounds.getMaxY() - YSIZE; 
      dy = -dy; 
     } 
    } 

//Gets the shape of the ball at its current position. 
public Ellipse2D getShape() 
{ 
return new Ellipse2D.Double(x,y, XSIZE, YSIZE); 
} 

private static final int XSIZE = 15; 
private static final int YSIZE = 15; 
private double x = 0; 
private double y = 0; 
private double dx = 1; 
private double dy = 1; 
} 

類BallComponent

import java.awt.*; 
import java.util.*; 
import javax.swing.*; 
/** 
* 
* @author Fahmi 
*/ 
//The component that draws the balls. 
class BallComponent extends JPanel { 

//Add a ball to the component 
public void add(Ball b) 
{ 
    balls.add(b); 
} 

public void paintComponent(Graphics g) 
{ 
    super.paintComponent(g); //erase back 
    Graphics2D g2 = (Graphics2D) g; 
    for (Ball b : balls) 
    { 
     g2.setColor(Color.RED); 
     g2.fill(b.getShape()); 
    } 
} 
private ArrayList<Ball> balls = new ArrayList<Ball>(); 
} 

我創建3個文件1包，BounceTugas，Ball和BallComponent .. 我希望任何人都可以解決這個問題

Answer 1

我已經修改了你的類。

這裏是空方法的實現。

• 變化球的尺寸（BounceTugas.java）

  public void changeBallSize(){ 
      if(Ball.getXSIZE()==15){ 
       Ball.setXSIZE(45); 
      }else{ 
       Ball.setXSIZE(15); 
      } 
      if(Ball.getYSIZE()==15){ 
       Ball.setYSIZE(45); 
      }else{ 
       Ball.setYSIZE(15); 
      } 
  
      Ball.setCircle(!Ball.isCircle()); 
  
      comp.repaint(); 
  } 
  

• 變化球型（BouceTugas.java）

  public void changeBallType(){ 
      Ball.setCircle(!Ball.isCircle()); 
  
      comp.repaint(); 
  } 
  

• 移除球（BounceTugas.java）

  public void removeBall() { 
      if(comp.getBalls().size()>0){ 
       comp.getBalls().remove(0); 
      } 
      comp.repaint(); 
  } 
  

• 改變球的顏色（BounceTugas.java）

  public void changeColor() { 
  
      if (comp.getColor() == Color.RED) { 
       comp.setColor(Color.GREEN); 
      } else { 
       comp.setColor(Color.RED); 
      } 
  
      comp.repaint(); 
  } 
  

• BallComponent.java

  public void paintComponent(Graphics g) { 
      super.paintComponent(g); // erase back 
      Graphics2D g2 = (Graphics2D) g; 
      for (Ball b : balls) { 
       g2.setColor(color); 
       g2.fill(b.getShape()); 
      } 
  } 
  
  private ArrayList<Ball> balls = new ArrayList<Ball>(); 
  
  private Color color = Color.RED; 
  
  public Color getColor() { 
      return color; 
  } 
  
  public void setColor(Color color) { 
      this.color = color; 
  } 
  
  public ArrayList<Ball> getBalls() { 
      return balls; 
  } 
  

• Ball.java

  public Shape getShape() { 
      if(circle){ 
       return new Ellipse2D.Double(x, y, XSIZE, YSIZE); 
      }else{ 
       return new Rectangle((int)x,(int)y,XSIZE,YSIZE); 
      } 
  } 
  
  private static boolean circle=true; 
  private static int XSIZE = 15; 
  private static int YSIZE = 15; 
  
  public static int getXsize() { 
      return XSIZE; 
  } 
  
  public static int getYsize() { 
      return YSIZE; 
  } 
  
  public static int getXSIZE() { 
      return XSIZE; 
  } 
  
  public static void setXSIZE(int xSIZE) { 
      XSIZE = xSIZE; 
  } 
  
  public static int getYSIZE() { 
      return YSIZE; 
  } 
  
  public static void setYSIZE(int ySIZE) { 
      YSIZE = ySIZE; 
  } 
  
  public static boolean isCircle() { 
      return circle; 
  } 
  
  public static void setCircle(boolean circle) { 
      Ball.circle = circle; 
  }