Palindrome Detector Overview
Published: 2019-03-28 01:50:34

---
title: Palindrome Detector Overview
published: true
description: Summary of Challenges Faced doing Palindrome Detector Project
tags: 
---
Today, I will be discussing the challenges I faced making my Palindrome Detector that I mentioned in my last post.

It turns out that the professor actually wanted us to implement the concept of a stack into this project. I couldn't simply work off of one String. That didn't make things too challenging because the professor gave us the outline for a Stack class that I just had to use.

One challenge I faced was trying to put a file as a parameter so I can check to make sure it can be opened first before making a new Scanner. I wanted to do this in a separate method so as to keep my main method clean. I found a post online that showed how to do it using InputStream in the method's parameter and new FileInputStream in the call, but an error message popped up. I ended up putting my file checker in my main. I'm sure there has to be some way to do it, but I couldn't find any. If you guys have any advice, I would greatly appreciate it

Another challenge I faced was when I was making my reverse stack method (makeReverStack). Initially, I decided I wanted to use the forward stack as one parameter since I already have it, anyway. I popped the values from it and pushed it to the reverse stack. However, an error message kept popping up saying I was going out of bounds of an array. I noticed through extensive debugging putting prints in different places and checking the values of variables that my top variable for my forward stack is -1. 

I first checked to see where the error was occurring. I checked to make sure both of my stacks were filled. I found out one wasn't. I then checked to see if they had what they needed in them. They did. I checked to see how many iterations were happening with the loops. There was the appropriate amount. I checked that each had something in it. They did. Except the isFull method said otherwise (tying back into that top variable). It seems this was the result of popping. I assumed I could just use the forward stack from the parameter since it's just a separate object from the main, but it seems not. I think the Java might have made both objects (the one in my method and the one in my main) point to the same reference so that what I do in the method to the stack affects the one in my main.

To solve this, I decided to avoid using the forward stack and the pop method that affects the top variable. Instead, I just repeated the same thing I did with the forward stack method (makeLetterStack), except going backwards. I used the lettersOnly String instead of using the forward stack. I believe there is a way to circumvent this issue by using the .this operator from what I discovered online, but I don't have enough experience using it and I wanted to keep things simple since the forward stack method was already using the lettersOnly String.

The last big challenge I faced was trying to find out why my program was saying every line is a palindrome. I knew this error had to be occurring in my last method (printIfPali) because that's where the checking happens between both stacks and the printing occurs. I checked to see what the value of my boolean variable was. When I saw the variable was behaving as it should be, I checked my last if statement. I played around with the equal sign and found that a double equal sign made my program work fine while one equal sign made it work incorrectly. I believe this is because the = sign is supposed to be used when making something equal to something else. However, in an if statement, you should be using == to compare values.


-----
In my next post, I plan to discuss my progress on my Calculator project and discuss any new things I've learned for my side group project and for my Software Engineering final project. I want to try learning some SQL, Angular and Apache.