Problems with StringBuilders and Replacing Chars

Question

I need to generate a password of random letters and numbers, I've been successful so far, but what I need to do is take the password I generated, delete one character, add a number to the end. Once that's done, I need to search the password for the letters L and O and replace them with underscore.
When I call makeBetterPassword() - It outputs : 4 random letters and a bunch of squares
When I call makeEvenBetterPassword() - I get the following error.
Exception: java.lang.StringIndexOutOfBoundsException: String index out of range: -1
Here's my code - Any help would be greatly appreciated :)
public StringBuilder makeBetterPassword()
       makeBetterSB.setLength(passLength -1);
        makeBetterSB.append(randNumber);
      if(noise.nextBoolean() == true)
         makeBetterSB.reverse();
      return makeBetterSB;
   public void makeEvenBetterPassword()
      int indexStart = 0;
      int indexEnd = 0;
      for(int i = 0; i < makeBetterSB.length(); i++)
         indexStart = makeBetterSB.indexOf("l", 0);
         indexEnd = indexStart +1;
         makeBetterSB.replace(indexStart, indexEnd, "_");
   }

Answer 1

the3rdhero wrote:
I need to generate a password of random letters and numbers, I've been successful so far, but what I need to do is take the password I generated, delete one character, add a number to the end. Once that's done, I need to search the password for the letters L and O and replace them with underscore.
When I call makeBetterPassword() - It outputs : 4 random letters and a bunch of squaressquares: you have numbers in there that don't correspond to ASCII characters. You may want to limit the range of random numbers allowed.
>
When I call makeEvenBetterPassword() - I get the following error.
Exception: java.lang.StringIndexOutOfBoundsException: String index out of range: -1So the original password doesn't have any "l" characters and returns -1. You have to allow for this.