Java program delays whitespace strings from printing to console

This is a problem I've encountered several times, and always wondered why.

For my code below as an example, if a string of whitespace is entered, the method will not print. However, after the next input with a value string containing characters, it will print all the whitespace strings and the valid character containing string. Why is this delayed and stored in memory?

Example for the code below: Enter " " returns nothing. Enter " " returns nothing. Enter "SwiggitySwooty" returns " " \n " " \n "SwiggitySwooty" Explaination: The whitespace containing strings are delayed until a valid character string is entered.

Extra info: I use intellij, also happens when not sending the string to a method. I've also had this happen during a while(input.hasNext()) statement, in which I try to catch an invalid input as a string, when I want to take an integer. If I enter 'n' amount of legitimate integers, and then a string, it would print out my "please enter an integer" that 'n' amount of times like in this code.

Let me know if you guys need anything else!

/**
 * Created by JacobHein on 4/19/15.
 */
import java.util.Scanner;
public class FizzString {
/*TODO
* Given a string str, if the string starts with "f" return "Fizz". 
If the string ends
* with "b" return "Buzz". If both the "f" and "b" conditions are true, return
* "FizzBuzz". In all other cases, return the string unchanged. */
public static void main(String[] args) {
  Scanner input=new Scanner(System.in);

  while(input.hasNext()) {
    System.out.println(fizzString(input.nextLine()));
  }
}
public static String fizzString(String str) {
  String result=str;
  int l=str.length();
  if (str.charAt(0)=='f'||str.charAt(l-1)=='b') {
    result="";
    if (l>0) {
      if (str.charAt(0)=='f') {
        result="Fizz";
      }
      if (str.charAt(0)=='b') {
        result="Buzz";
      }
      if (l>1) {
      /*technique: continue the process if l>1 (within l>0 if statement),
      prevents breaking the program.*/
        if (str.charAt(l-1)=='b') {
          result="Buzz";
        }
        if (str.charAt(0)=='f'&&str.charAt(l-1)=='b') {
          result="FizzBuzz";
        }
      }/*end l>1*/
    }/*end l>0*/
  }/*end charAt if*/
  return result;
 }
 }