I need the program to prompt the user to continue to enter values whether the value they entered is positive or negative. Right now I can't get the program to run after entering a value whether it is negative or not. I need to keep the part of the program where if you enter a negative number it prints out IllegalArgumentException and shows where the error occurs. I need to prompt the user when the program is first run to enter a number.

import java.util.Scanner;

public class sqrt

{

public static double sqrt(int number) throws IllegalArgumentException

{

double perm_dev = 0.0001;

double prevguess=1, next_guess=1;

if(number<0)

throw new IllegalArgumentException("Negative Number");

do

{

prevguess=next_guess;

next_guess=(prevguess + (number/prevguess))/2;

}

while(Math.abs(next_guess - prevguess)>perm_dev);

return next_guess;

}

//main method

public static void main(String args[])

{

//scanner object creation

Scanner sc = new Scanner(System.in);

//scanning input

int num=sc.nextInt();

//checking num greater than 0 or not and throwing exception if it's not zero

if (num < 0)

{

throw new IllegalArgumentException(Integer.toString(num));

}

//else calling the sqrt function and printing the value

else

{

double val=sqrt(num);

System.out.println(val);

}

}

}