ma.java

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import java.io.*;
import java.util.*;
class circle{
int r,d;
double area,c;
circle(int f){r=f;}
public int zhi(){d=2*r;return d;}
public double zhou(){c=2*3.1416*r;return c;}
public double mian(){area=3.1416*r*r;return area;}
}
class ma{
public static void main(String args[]) throws java.io.IOException{
int a;
System.out.println("输入半径：");
a=(int)System.in.read()-48;
circle m=new circle(a);
System.out.println("半径是："+a);
System.out.println("直径是："+m.zhi());
System.out.println("周长是："+m.zhou());
System.out.println("面积是："+m.mian());
}
}