“return”似乎返回旧的变量值

I have a question regarding this

我对此有疑问

public class Palindrom
{
  public static boolean isPalindrom(String text)
  {
    boolean back = true; //return variable
    text = text.replaceAll("\s","");

    //checking special cases - text.length() = 0 or 1
    if (text.length() <= 1)
    {
      if (text.length() == 0)
      {
        System.out.println("An empty string cannot be a palindrom");
        back = false;
      }
      else
      {
        //checking if the single String-element is a letter
        if (Character.isLetter(text.charAt(0)) == true)
        {
          System.out.println("An single-character string - given that it is a valid word - is always a palindrom");
          back = true;
        }
        else
        {
          System.out.println("The String contains something that isn't a letter 1");
          back = false;
        }
      }
    }
    else
    {
      text = text.toLowerCase();

      //now we always have to check if the first and last element are letters and if they're equal
      if ((Character.isLetter(text.charAt(0)) && Character.isLetter(text.charAt(text.length() - 1))) == true)
      {
        //TEST
        //System.out.println("Checks if letters");

        if (text.charAt(0) == text.charAt(text.length() - 1)) 
        {
          back = true;

          //now we have to the recursive calling
          text = text.substring(1,text.length() - 1);

          //if the cut String has a length = 0, then there is no need to call the method again
          if (text.length() != 0)
          {
            //TEST
            System.out.println("Calls the method again");

            Palindrom.isPalindrom(text);
          }
          //else: we're finished
        }
        else
        {
          back = false;
        }
      }
      else
      {
        System.out.println("The String contains something that isn't a letter 2");
        back = false;
      }
    }

    System.out.println("four");
    System.out.println("back is : " + back);
    System.out.println("five");

    return back;
  }
}
pub