      1  import java.util.Scanner;

      2

      3  /**

      4     This program shows how you can prompt for input that fulfills

      5     a certain condition. Try entering negative values, such as

      6     -2 or -0.5, to see how they are rejected.

      7  */

      8  public class DoLoop

      9  {

     10     public static void main(String[] args)

     11     {

     12        Scanner in = new Scanner(System.in);

     13

     14        double value;

     15        do

     16        {

     17           System.out.print("Enter a number >= 0: ");

     18           value = in.nextDouble();

     19        }

     20        while (value < 0);

     21        double root = Math.sqrt(value);

     22        System.out.println("The square root of the number is " + root);

     23     }

     24  }