Thread: my do while isn't behaving (beginner)

I get a " java.lang.StringIndexOutOfBoundsException: String index out of range: 0". This seems like it should be too easy to mess up but here I am. Any help would be awsome, Thanks

import java.util.*;
public class classPractice2_10
{
  public static void main(String[]args)
  {
    Scanner kb = new Scanner(System.in);
 
    double length, width, area, perimeter;
    char repeat;
    String input;
 
   do
   {
    System.out.println("Please enter the length of the room. ");
    length = kb.nextDouble();
 
    System.out.println("Please enter the width of the room. ");
    width = kb.nextDouble();
 
    area = length * width;
    perimeter = (length + length) + (width + width);
 
    System.out.printf("The area of your room is %.3f and the perimeter of your room is %.3f \n",area,perimeter);
 
    System.out.println("Do you wish to calculate another room? ");
    System.out.print("Enter Y for yes and N for no ");
    input = kb.nextLine();
    repeat = input.charAt(0);
   }while (repeat == 'y' || repeat == 'Y');
  }
}

Thanks for being so quick.

java.lang.StringIndexOutOfBoundsException: String index out of range: 0
at java.lang.String.charAt(Unknown Source)
at classPractice2_10.main(classPractice2_10.java:31)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Nativ e Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknow n Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Un known Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at edu.rice.cs.drjava.model.compiler.JavacCompiler.ru nCommand(JavacCompiler.java:272)
>

Ok, so Ive been staring at post #2 and I dont get what your telling me. I don't want an empty string, I was hoping for another message to prompt my user for an answer to the continue. lol sorry for being hard headed

Always remember that the user might actually enter an empty line. Better check for this scenario in your code too.

Ok, thanks norm that does work but it seems weird that i have to do that is that normal? good point Cornix, my solution to your empty line doesnt work. Any ideas on how to correct that?

import java.util.*;
public class classPractice2_10
{
  public static void main(String[]args)
  {
    Scanner kb = new Scanner(System.in);
 
    double length, width, area, perimeter;
    char repeat;
    String input = "";
 
   do
   {
    System.out.println("Please enter the length of the room. ");
    length = kb.nextDouble();
 
    System.out.println("Please enter the width of the room. ");
    width = kb.nextDouble();
 
    area = length * width;
    perimeter = (length + length) + (width + width);
 
    System.out.printf("The area of your room is %.3f and the perimeter of your room is %.3f \n",area,perimeter);
 
    System.out.println("Do you wish to calculate another room? ");
    System.out.print("Enter Y for yes and N for no ");
    input = kb.nextLine();
    input = kb.nextLine();
    repeat = input.charAt(0);
     if (input == " ");
    {
      System.out.println("Please Enter Y or N");
    }
   }while (repeat == 'y' || repeat == 'Y');
  }
}