interface Cal{
//使用接口方式计算圆和正方形的面积(S)和周长(L);cal:计算器;
//get 获得
public static final double PI = 3.14;
//求面积
public double getS();
//求周长
public double getL();
}
//创建正方形的类
class Rect implements Cal{
double r;
public Rect(double r){
this.r = r;
}
public double getS(){
return r*r;
}
public double getL(){
return 4*r;
}
}
//创建圆的类
class Circle implements Cal{
double r;
public Circle(double r){
this.r = r;
}
public double getS(){
return Cal.PI*r*r;
}
public double getL(){
return 2*Cal.PI*r;
}
}
public class TestCal{
public static void main(String[] args){
Rect r = new Rect(10.0);
double rS = r.getS();
double rL = r.getL();
System.out.println(“正方形的面积是:”+rS+" 正方形的周长是:"+rL);
Circle c = new Circle(10.0);
double cS = c.getS();
double cL = c.getL();
System.out.println("圆的面积是:"+cS+" 圆的周长是:"+cL);
}
}
