See below.
 while  Loop Version
The first iteration of the loop body
can be made to happen by initializing
chars to "yes."
This is slighly awkward.
import java.util.Scanner;
class SqrtCalc
{
  public static void main( String[] args )
  {
    String chars;
    double x;
    Scanner scan = new Scanner(System.in );
    chars = "yes" ;        // enable first iteration of the loop
    while ( chars.equals( "yes" ) )
    {
      System.out.print("Enter a number-->");
      x = scan.nextDouble(); 
      chars = scan.nextLine();   // flush rest of the line
      System.out.println("Square root of " + x + " is " + Math.sqrt( x ) );
      System.out.print("Do you wish to continue? (yes or no) --> ");
      chars = scan.nextLine();
   }
  }
}
        
Examine the code (again.)  How would it be written with a
for loop?