java小问题：如何建立一个point类输出正方形四个顶点坐标.

题目

java小问题：如何建立一个point类输出正方形四个顶点坐标.
一个正方形和长方形继承了矩形,然后算面积和输出顶点坐标.本来我想直接在point类中设置p1x=0,p1y=0,p2x=Quadrilateral.wid.可是系统报错说要把wid改为static.然后我就不知道怎么修改了.
abstract class Quadrilateral {
protected double len;
protected double wid;
public Quadrilateral(double len,double wid){
this.len=len;
this.wid=wid;}
public abstract double area();
}
class Rectangle extends Quadrilateral{
Rectangle(double num,double num1){
super(num,num1);}
public double area(){
return len*wid;}
}
//省略了square类了.
class Point extends Quadrilateral{ double p1x=0,p1y=0;
double p2x=Quadrilateral.wid;
}
class Test {
public double result(Quadrilateral quadrilateral){
return quadrilateral.area();}
public static void main(String[] args) {
Rectangle r=new Rectangle(5,10);
Square s=new Square(10,10);
Test test=new Test();
System.out.println("矩形面积："+test.result(r));
System.out.println("正方形面积："+test.result(s));
}
}

答案