问创建一个“项目”类(Java/swing)

EN

public class Bullets extends JComponent{
//x,y = the towers coordinates, where the shoot initiliazes from.
//tx, ty = Target's x and y coordinates.
private int x,y,tx,ty;
private Point objectP = new Point();
    public Bullets(int x, int y, int tx, int ty)
        this.x = x;
        this.y = y;
        this.tx = tx;
        this.ty = ty;
        setBounds(x,y,50,50);
        //Create actionlistener to updateposition of the bullet (setLocation of component)
        ActionListener animate = new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent ae) {

            setBulletLocation();


        }
        };
        Timer t = new Timer(500,animate);
        t.start();

    }
public void setBulletLocation() {
    objectP = this.getLocation();
    double xDirection =  5* Math.cos(-(Math.atan2(tx - x, tx - y))+ 90);
    double yDirection =  5* Math.sin(-(Math.atan2(tx - x, tx - y))+ 90);
    System.out.println(xDirection + " , " + yDirection);
    x = (objectP.x + (int) xDirection);
    y = (objectP.y + (int) yDirection);
    setLocation(x, y);

    repaint();
 }
@Override
protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    g.fillOval(0, 0, 50, 50);
}