如何在小行星程序中显示我的太空飞船？

Question

我正在尝试完成一个小行星项目。 我有四节课。 小行星，多边形，游戏和星号。 我正在制造一艘新船，这是船的子类。 我是Java新手。 我试图制作一个新的飞船对象，但无法使其出现在屏幕上。 https://docs.oracle.com/javase/7/docs/api/java/awt/Graphics.html但是，在船级中，我使用fillPolygon现在显示在屏幕上。 但是我知道写方法。 我该如何使用飞船对象使飞船显示出来。 我在下面提供我的课程。

 package asteroids;

/*
CLASS: Asteroids
DESCRIPTION: Extending Game, Asteroids is all in the paint method.
NOTE: This class is the metaphorical "main method" of your program,
   it is your control center.
Original code by Dan Leyzberg and Art Simon
*/
import java.awt.*;
import java.awt.event.*;

class Asteroids extends Game {
   static int counter = 0;

public Asteroids() {
  super("Asteroids!",800,600);
  this.setFocusable(true);
  this.requestFocus();
 }

public void paint(Graphics brush) {
    brush.setColor(Color.black);
    brush.fillRect(0,0,width,height);

    // sample code for printing message for debugging
    // counter is incremented and this message printed
    // each time the canvas is repainted
    counter++;
    brush.setColor(Color.white);
    brush.drawString("Counter is " + counter,10,10);
    ship p = new ship(
            new Point[] {new Point(1,1),new Point(3,1),new Point(1.5,2)},
            new Point(3,3),
            0);


    brush.setColor(Color.red);
    p.paint(brush );

 }

public static void main (String[] args) {
    Asteroids a = new Asteroids();

    a.repaint();










   }
}  

多边形类

enter code herepackage asteroids;

/*

类：多边形描述：多边形是空间中的一系列点，这些点由一组这样的点，偏移和旋转定义。 偏移量是形状的原点和中心之间的距离。 旋转度数为0-360。 用法：您打算用一组永远定义其形状的点实例化该类，然后通过重新定位和旋转该形状来对其进行修改。 在定义形状时，将使用您提供的点的相对位置，换句话说：{（0,1），（1,1），（1,0）}与{（9,10） ，（10,10），（10,9）}。

class Polygon {
  private Point[] shape;   // An array of points.
  public Point position;   // The offset mentioned above.
  public double rotation; // Zero degrees is due east.

 public Polygon(Point[] inShape, Point inPosition, double inRotation) {
    shape = inShape;
    position = inPosition;
    rotation = inRotation;

   // First, we find the shape's top-most left-most boundary, its origin.
    Point origin = shape[0].clone();
    for (Point p : shape) {
  if (p.x < origin.x) origin.x = p.x;
  if (p.y < origin.y) origin.y = p.y;
 }

// Then, we orient all of its points relative to the real origin.
   for (Point p : shape) {
     p.x -= origin.x;
     p.y -= origin.y;
  }
}


  // "getPoints" applies the rotation and offset to the shape of the polygon.
   public Point[] getPoints() {
   Point center = findCenter();
   Point[] points = new Point[shape.length];
    for (int i = 0; i < shape.length; i++) {
    for (Point p : shape) {
      Point p = shape[i];
       double x = ((p.x-center.x) * Math.cos(Math.toRadians(rotation)))
           - ((p.y-center.y) * Math.sin(Math.toRadians(rotation)))
           + center.x/2 + position.x;
  double y = ((p.x-center.x) * Math.sin(Math.toRadians(rotation)))
           + ((p.y-center.y) * Math.cos(Math.toRadians(rotation)))
           + center.y/2 + position.y;
  points[i] = new Point(x,y);
  }
  return points;
 }

  // "contains" implements some magical math (i.e. the ray-casting algorithm).
 public boolean contains(Point point) {
  Point[] points = getPoints();
  double crossingNumber = 0;
   for (int i = 0, j = 1; i < shape.length; i++, j=(j+1)%shape.length) {
    if ((((points[i].x < point.x) && (point.x <= points[j].x)) ||
       ((points[j].x < point.x) && (point.x <= points[i].x))) &&
      (point.y > points[i].y + (points[j].y-points[i].y)/
       (points[j].x - points[i].x) * (point.x - points[i].x))) {
    crossingNumber++;
  }
 }
return crossingNumber%2 == 1;
}

 public void rotate(int degrees) {rotation = (rotation+degrees)%360;}

 /*
 The following methods are private access restricted because, as this access
 level always implies, they are intended for use only as helpers of the
 methods in this class that are not private. They can't be used anywhere else.
 */

 // "findArea" implements some more magic math.
 private double findArea() {
   double sum = 0;
    for (int i = 0, j = 1; i < shape.length; i++, j=(j+1)%shape.length) {
    sum += shape[i].x*shape[j].y-shape[j].x*shape[i].y;
  }
  return Math.abs(sum/2);
  }

 // "findCenter" implements another bit of math.
 private Point findCenter() {
  Point sum = new Point(0,0);
   for (int i = 0, j = 1; i < shape.length; i++, j=(j+1)%shape.length) {
     sum.x += (shape[i].x + shape[j].x)
           * (shape[i].x * shape[j].y - shape[j].x * shape[i].y);
    sum.y += (shape[i].y + shape[j].y)
           * (shape[i].x * shape[j].y - shape[j].x * shape[i].y);
   }
    double area = findArea();
   return new Point(Math.abs(sum.x/(6*area)),Math.abs(sum.y/(6*area)));
 }

}船级包裹小行星；

import java.awt.Color;
import java.awt.Graphics;

public class ship extends Polygon{
  static int counter=0;

   public ship(Point[] inShape, Point inPosition, double inRotation) {
       super(inShape, inPosition, inRotation);
        // TODO Auto-generated constructor stub
   }

   public void paint(Graphics brush) {
        brush.fillPolygon(new int []{400,380,380,420,420,400},new int[]    {300,320,360,360,320,300},6); 

 }


public void drawPolygon(Point[] points, Point point, int i) {
    // TODO Auto-generated method stub

}

}

 Any help will be appreciated ,thanks

Answer 1

小行星应直接或间接（通过Game）扩展JFrame。

实例化应扩展JFrame的Asteroids类后，请执行以下操作：

asteroid.setVisible(true);

将出现一个新的jpanel，并且您的绘制方法将在该jpanel的画布上绘制。