JAVA继承类求几何图形面积周长代码

class shap2D

{

static double getArea; //面积

static double getPerimeter; //周长

}

class circle extends shap2D

{

double r;

double getRadius(){return r=2;}

double getArea() {return Math.PI*r*r;}

double getPerimeter() {return 2*Math.PI*r;}

public String toString()

{

String s;

return s="周长："+getPerimeter()+"面积:"+getArea();

}

}

class Triangle extends circle

{

double a,b,c;

Triangle (double x,double y,double z)

{a=x; b=y;c=z;}

void setA(double x){a=x;}

double getA(){return a;}

public double getPerimeter() {return a+b+c;}

public double getArea()

{

double s=(a+b+c)/2;

return Math.sqrt(s*(s-a)*(s-b)*(s-c));

}

public boolean isTriangle()

{

boolean flag=false;

if(a>0&&b>0&&c>0&&a+b>c&&a+c>b&&c+b>a) flag=true;

return flag;

}

}

class rectangle extends circle

{

double a,b;

rectangle(double x,double y)

{a=x; b=y;}

void setA(double x){a=x;}

double getA(){return a;}

public double getPerimeter() {return 2*(a+b);}

public double getArea() {return a*b;}

}

public class Shap

{

public static void main(String args[])

{

circle c1=new circle();

System.out.println("圆的的半径"+c1.getRadius()+c1.toString());

Triangle t=new Triangle(3,4,5);

System.out.println("三角形周长："+t.getPerimeter());

if(t.isTriangle())

System.out.println("三角形面积"+t.getArea());

rectangle r=new rectangle(4,5);

System.out.print("矩形"+t.toString());

}