title: Infinite While Loop in Java
body: <p>Hey there!  I'm trying to do some data input validation but I haven't been able to figure it out.  I'm getting an infinite while loop in when I try to validate if the first character entered is a letter. . . .</p>
  
  <p>Thanks for your help!</p>
  
  <pre><code>public class methods
  {
      public static void main(String args[]) throws IOException
      {
          String input ="";
          int qoh=0;
          boolean error=true;
  
          Scanner keyboard = new Scanner (System.in);
  
          //while (error)
          //{
              //error=true;
  
          while (error==true)
          {
             System.out.print("\nEnter Quantity on Hand: ");
             input = keyboard.nextLine();
  
             if (input.length() &lt;1)
             {
                 System.out.println("\n**ERROR06** - Quantity on hand must be between 0 and 500");
                 error=true;
                 System.out.println(qoh);
                 System.out.println(input);
              }
              else
              {
                  error=false;
              }
          }
  
          error = true;
  
          while (error==true)
          {
              if (Character.isLetter(input.charAt(0)))
              {
                  System.out.println("\n**ERROR06** - Quantity on hand must be between 0 and 500");
                  error=true;
                  System.out.println(qoh);
                  System.out.println(input);
               }
               else
               {
                   qoh = Integer.parseInt(input);
                   error=false;
                }
            }
        }
    }
  </code></pre>