第二周：Greenfoot游戏开发（螃蟹吃沙蠕虫）

先安装Greenfoot。

public class World{//成员变量private int width = 450;private int height = 450;private Crab[] crab = new Crab[300];//构造器World(){}World(int width, int height){this.width = width;this.height = height;}//成员方法public void setWidth(int width){this.width = width;}public int getWidth(){return this.width;}public void setHeight(int height){this.height = height;}public int getHeight(){return this.height;}}