第一篇程序

import java.io.;
class Z2_3_Circle{
final float PI=3.14159f;
float r;
public void setRadius(float r1)
{
r=r1;
}
public float getRadius()
{
return r;
}
public float getArea()
{
return PIr*r;
}

public static void main(String[] args)
{
Z2_3_Circle c1=new Z2_3_Circle();
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
String str =null;
float rr;
System.out.println("输入半径:");
try{
str=br.readLine();
}catch(IOException e){
e.printStackTrace();
}
rr=Float.parseFloat(str);
c1.setRadius(rr);
float Area = c1.getArea();
System.out.print("圆的半径="+c1.getRadius()+" 面积="+Area);
}
}