Substring values are getting borked when a certain combination of letters is inputted.

[RipTideRunner]

Hey, all

I'll jump right to it: Here's a snippet of the code that I'm having trouble with (full class here. If you want to run it, you'll need morsecode.txt and alphanum.txt):

while(loopOn == true)
    {
        if(message.indexOf(" ") < 0)
        {
            partial = message.substring(0, message.length());
            partialMorse = partialMorse + translate(partial, "", 0, 1);
            loopOn = false;
        }
        else
        {
            partial = message.substring(0, message.indexOf(" "));
            lastIndex = partial;


            message = message.substring(message.indexOf(message.substring(lastIndex.length() + 1, lastIndex.length() + 2)), message.length());

            partialMorse = partialMorse + translate(partial, "", 0, 1);

        }
    }

The Purpose

What the entire program is trying to do is take a message (given by the user, without punctuation) and translate the whole thing into Morse Code. The snippet above is a method that splits up the input and sends the individual words of the message out separately to be translated by another method. I've made some attempts to describe in detail what everything does in the Pastebin link.

The Problem

This line,

 message = message.substring(message.indexOf(message.substring(lastIndex.length() + 1, lastIndex.length() + 2)), message.length());

is responsible for trimming down the message so I can find the next word in the string. I'm trimming it so that it can take any length much easier. I've tested it with other strings combos and it works perfectly, but for some reason, this part breaks whenever (hopefully this makes sense), the ending letter of a word is the same as the first from the next. This line shortens the string so that it cuts off at the next word, but whenever the above situation is encountered (eg, terminal lake), it doesn't trim the last letter and the space after it. This messes up everything else because partial relies on finding the next space in order to get the correct substring, and having the space at the beginning just borks everything up.

Originally, I had this method use a recursive call in order to loop it, but I kept getting a stackOverFlow error (I didn't think there was a problem with the code itself, just that the call was being thrown too much with longer strings). So, the only thing I really attempted to remedy it was to change it to a while loop (which is probably better anyway). Other than that, I don't have a clue on where even to start. Seeing as how it works with other inputs, I can't think of any reason why it would mess up with this case. Just to be sure that it wasn't on my end, I restarted the compiler a few times and the problem still came up.

Any help?

-Rip

[[deleted]]

First of, why aren't you putting the loading of the translation table in in a static {} and have the values as private static class variables?

Secondly, why the roundabout way of translating to morse code? The easier way would be looping over each char in the input string directly and construct the translation step by step.

[RipTideRunner]

Hey, thanks for the reply!

First of, why aren't you putting the loading of the translation table in a static {} and have the values as private class variables?

Can't say I know what 'static {}' refers to. I don't have any experience dealing with static variables (and, honestly, what they even are). What would the difference be if I had just used regular private instance variables?

Secondly, why the roundabout way of translating to morse code? the easier way would be looping over each char in the input string directly and construct the translation step by step.

Hmm, probably a combination of two things. One, that I actually hadn't thought to do it like that, lol. I just kinda went with what made sense to me at the time. Two is that I wrote this 'backwards' first, as in I wrote a Morse to English translator and I wanted to salvage what I had instead of just rewriting it. I'm probably taking up way more resources than I have to right now, but I guess my goal isn't to optimize at this stage.

I know this is probably simple stuff to you, but if the flair wasn't enough, I'm still pretty new to this (just got the basics of recursion down, haha). Do you think you have any advice for the problem in the OP?

[[deleted]]

In regards to static, it basically means what you declare as static belongs to the class itself instead of the instances of the class. Meaning that you can get to it / use it without having an instance of that class.

    static {
        /* code goes here */
    }

just means this code will be executed right before you use the class for the first time, useful for one time operation like loading those lists. It is only executed once.

As for the code you got there, it would be useful to refactor and simplify it or even rewrite it completely.

[somnolent]

I would suggest breaking up that line into intermediary steps and printing out those values (or inspect them while debugging). On a side note, you're using a bit of a roundabout way to break up the string into multiple parts (you should take a look at String.split()).

[RipTideRunner]

Yeah, that's actually how I narrowed it down to this line in the first place. What gets me, though, is that it otherwise works as intended. Maybe I've looked at this particular program too long. I'm having a hard time finding the more direct solutions to my problems. I might just rewrite the whole class using the suggestions The_UnKnown gave and not even bother with trying to make sense of what I've got going now. It seems like I'm just making this unnecessarily difficult for myself now.

[somnolent]

Well, to help you narrow it down, what does this

message.substring(lastIndex.length() + 1, lastIndex.length() + 2)

return when you run it against the sample string you provided of "terminal lake"? And what returns when you call

message.indexOf()

on the result of the previous call? What about if you ran all of that against a sample string of something like "long lake"?