Thread: StringIndexOutOfBounds exception

I'm trying to make a program that analyzers strings for certain pieces of information such as the length of the string, the number of vowels, and the number of words. However, while trying to analyze for the number of vowels in the string, I ran into an error. I tried figuring out what was going wrong on my own, but I couldn't seem to find what my problem was. If anyone would care to look through and see what I was doing wrong, it'd be greatly appreciated. The error code is posted below the program code. I am able to compile and run the program, but whenever I enter any piece of data, the program crashes from a StringIndexOutOfBounds exception. This is my first post on this forum by the way, so if I did anything wrong or didn't include necessary information, I'm sorry Just message me back and I'll try to fix it.

import java.util.*;
 
class ClrScrn {
    static void clrScrn() {
        for(int lineCounter = 0; lineCounter <= 75; lineCounter++) {
            System.out.println();
        }
    }
}
 
class Analysis {
    int vowelCounter(String userString, int stringLength) {
        char vowels[] = {'a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U'};
        int numOfVowels = 0;
 
        for(int stringCounter = 0; stringCounter <= stringLength; stringCounter++) {
            char stringFocus = userString.charAt(stringCounter);
 
            for(int vowelCounter = 0; vowelCounter <= 9; vowelCounter++) {
                if(stringFocus == vowels[vowelCounter]) numOfVowels++;
            }
        }
 
        return numOfVowels;
    }
}
 
class Input {
    String getString() {
        Scanner scan = new Scanner(System.in);
 
        String userString = "";
 
        do {
            System.out.print("Please enter a string for me to analyze: ");
            userString = scan.nextLine();
 
            if(userString == "") System.out.println("\n\nError: Invalid entry.Please try again...");
            else return userString;
        } while (userString == "");
 
        return userString;
    }
}
 
class StringAnalyzer {
    public static void main(String[] args) {
        ClrScrn.clrScrn();
        System.out.println("\n\n");
 
        Scanner scan = new Scanner(System.in);
 
        Input userInput = new Input();
 
        do {
            String userString = userInput.getString();
            int stringLength = userString.length();
 
            Analysis Analyzer = new Analysis();
            int vowelNum = Analyzer.vowelCounter(userString, stringLength);
 
 
            System.out.println("String:   " + userString);
            System.out.println("Length:   " + stringLength);
            System.out.println("Vowels:   " + vowelNum + "\n");
 
            System.out.print("Would you like to run the analyzer again (y/n): ");
            String repeat = scan.next();
 
            if(repeat == "y") break;
        } while(true);
 
        System.out.println("\n\n");
    }
}

Error:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 4
	at java.lang.String.charAt(String.java:658)
	at Analysis.vowelCounter(StringAnalyzer.java:26)
	at StringAnalyzer.main(StringAnalyzer.java:69)

P.S. I entered "test" in the above trial

Originally Posted by aussiemcgr

Instead of looping while stringcounter is less than or equal to stringLength, try looping while stringCounter is less than stringLength (no equals to).

Awesome, thanks! That fixed my issue there. However, I've run into another issue with my code that I need a bit of help with if anybody can provide it. I've been having a recurring issue with my code when I try to prompt the user if they would like to run the program again without terminating. What I've been trying to do is make it so that when they enter "n" (located at the end of the code, it's one of the last lines in the main method) the program would terminate. If they enter "y" then the program would start from the beginning. If they enter anything other than y or n, the program would output an error message telling them so, and it would re-prompt for an appropriate response.

I've edited the last bit of the code, so now I'm trying to do what I just mentioned by breaking to a label located at the start of the first do/while loop (so that when it breaks to the label, the program should just bypass the loop and end the program, right?), but I can't seem to get it to work. I'm not sure if I'm using one of the pieces wrong, or if there's just something wrong with my code. I've posted the edited main method below, since that seems to be the only part that is messed up (and the only part that I changed, except for what Aussiemcgr mentioned above)

class StringAnalyzer {
    public static void main(String[] args) {
        ClrScrn.clrScrn();
        System.out.println("\n\n");
 
        Scanner scan = new Scanner(System.in);
 
        Input userInput = new Input();
 
        MainLoop:
        do {
            String userString = userInput.getString();
            int stringLength = userString.length();
 
            Analysis Analyzer = new Analysis();
            int vowelNum = Analyzer.vowelCounter(userString, stringLength);
 
 
            System.out.println("String:   " + userString);
            System.out.println("Length:   " + stringLength);
            System.out.println("Vowels:   " + vowelNum + "\n");
 
            String repeat;
 
            do {
                System.out.print("Would you like to run the analyzer again (y/n): ");
                repeat = scan.next();
 
                if(repeat == "n") break MainLoop;
                else if(repeat == "y") break;
 
                System.out.println("Error: Invalid Entry. Please try again.\n");
            } while(true);
        } while(true);
 
        System.out.println("\n\n");
    }
}

I also included a test run of the program to show what I'm talking about when I say that it doesn't end.

Please enter a string for me to analyze: test
String:   test
Length:   4
Vowels:   1
 
Would you like to run the analyzer again (y/n): n
Error: Invalid Entry. Please try again.
 
Would you like to run the analyzer again (y/n): y
Error: Invalid Entry. Please try again.