package test13;
public class C5_12
{
public static void main(String[] args)
{
double x;
circle ss=new circle(5.0);
x=ss.area();
System.out.print("圆的面积="+x);
x=ss.perimeter();
System.out.print("圆的周长="+x);
}
}class circle
{
double r;
final double PI=3.14159;
public circle(double r);
{
this.r=r;
}
double area();
{
return PI*r*r;
}
double perimeter()
{
return 2*(this.area()/r);
}
}
public class C5_12
{
public static void main(String[] args)
{
double x;
circle ss=new circle(5.0);
x=ss.area();
System.out.print("圆的面积="+x);
x=ss.perimeter();
System.out.print("圆的周长="+x);
}
}class circle
{
double r;
final double PI=3.14159;
public circle(double r);
{
this.r=r;
}
double area();
{
return PI*r*r;
}
double perimeter()
{
return 2*(this.area()/r);
}
}
{
this.r=r;
}
double area(); ->多了一个分号了
{
return PI*r*r;
}