7.java final 常量的定义

import java.util.Scanner;

public class FinalNew {
public static final double PI=3.1415926f;
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner input =new Scanner(System.in);
System.out.println("请输入三角形的半径");
double dRed=input.nextDouble();
System.out.println("三角形的周长为："+2*PI*dRed);

}

}