Question

用JAVA写一个求圆的面积的程序。谁帮帮忙

Answer 1

private static final double e = 3.1415926;
public static void main(String[] args){
System.out.println("请输入圆的半径:");
Scanner scan = new Scanner(System.in);
double r = scan.nextDouble();
getCircleArea(r);
}

/**
* 求圆的面积
* @param r 半径
* @return
*/
public static void getCircleArea(double r){
System.out.println(e*r*r);
}

Answer 2

public class Test {
public static void main(String args[]){

System.out .println("请输入半径长度");
System.out.println("area=="+ getArea());
}
private static double getArea(){
double p=3.14;

Scanner scan = new Scanner(System.in);
double radius =0.0;
boolean flag=true;
while(flag){
try{
radius= Double.parseDouble(scan.nextLine());
flag=false;
}catch(Exception e){
System.out.println("请输入数字!");
}
}
return p*radius*radius;
}
}

Answer 3

公式啊，看api里数学函数吧