Question

我试图用Java创建一个重力/太阳系类型模拟器，而我在将圆圈绘制到JPanel时遇到了麻烦。这是我的代码：

public class GUI {

public static void createAndShowGUI() {
    JFrame f = new JFrame("Swing Paint Demo");
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    f.add(new MyPanel());
    f.pack();
    f.setVisible(true);

 } 
}

class MyPanel extends JPanel {

ArrayList <body> system = new ArrayList<body>();
public MyPanel() {
    add(new body(1000,20,Color.yellow,0,0,100,100));
    add(new body(10,5,Color.black,5,0,100,50));
}

public void add(body b){system.add(b);}


public Dimension getPreferredSize() {
    return new Dimension(600,600);
}

protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D) g;

    for (body b: system) {
        Ellipse2D object = new Ellipse2D.Double();
        object.setFrameFromCenter(
            b.getposx() - b.getSize(),
            b.getposy() - b.getSize(),
            b.getposx(),
            b.getposy());
        g2.setColor(b.getColor());
        g2.fill(object);
    }
}  

}

这是身体类：

public class body {
public body(){
    mass = 100;
    size = 1;
    velX = 0;
    velY = 0;
    posX = 0;
    posY = 0;
    color = Color.white;
}

public body(int mass, int size, Color color, double velX, double velY, double posX, double posY){
    body.mass = mass;
    body.size = size;
    body.color = color;
    body.velX = velX;
    body.velY = velY;
    body.posX = posX;
    body.posY = posY;

}
//Getters
public int getMass(){return mass;}
public int getSize(){return size;}
public double getvelx(){return velX;}
public double getvely(){return velY;}
public double getposx(){return posX+velX;}
public double getposy(){return posY+velY;}
public Color getColor(){return color;}
//Setters
public static void setMass(int m){mass = m;}
public static void setSize(int s){size = s;}
public static void setvelx(double v){velX = v;}
public static void setvely(double v){velY = v;}
public static void setposx(double p){posX = p;}
public static void setposy(double p){posY = p;}
public static void setColor(Color c){color = c;}

//Member Variables
private static Color color;
private static int mass;
private static int size;
private static double velX;
private static double velY;
private static double posX;
private static double posY;

}

到目前为止，它只会绘制最后添加的对象。我希望能够跟踪和显示尽可能多的主体，这似乎是最简单，最节省CPU的解决方案。这是最好的方法吗？如果是这样，我做错了什么？

提前致谢！

Answer 1

类名以大写字母开头（即应该是Body）。
不要在课堂上使用静态变量和方法。您的所有Body个对象与创建的最后一个Body对象共享相同的值。

用Java绘制多个对象

1 个答案: