Recursive method: StringIndexOutOfBoundsException

Question

I am creating a program that takes in two strings and then compares the two to determine if the characters of the first string are contained in the second string (in no order).

I used a count integer to keep track of position

Unfortunately, I am getting StringIndexOutOfBoundsException: String index out of range: 0 upon executing the main and entering in "elf" for the first word, and "self" for the second for example.

    public static boolean containedWordsCheck(String firstWord, String secondWord, int count) {
//Default rule for setting to false if the size of the first word is larger than the second
        if (firstWord.length() > secondWord.length())
            return false;
        //Default rule for setting to true if both strings are empty
        if (firstWord.isEmpty() && secondWord.isEmpty())
            return true;
        if (firstWord.charAt(0) == secondWord.charAt(count))
                    return containedWordsCheck(firstWord.substring(1, firstWord.length()), secondWord, 0);
        else if (firstWord.charAt(0) != secondWord.charAt(count) && count + 1 < secondWord.length())
                    return containedWordsCheck(firstWord, secondWord, count + 1);
        else
                    return false;

Maybe my eyes are bad but I can't see where I am going out of bounds

Main for clarity:

 public static void main(String[] args) {
    String firstWord = userWord.nextLine();
    String secondWord = userWord.nextLine();
    int position = 0;
    if (containedWordsCheck(firstWord, secondWord, position))
        System.out.println("They are contained!");
    else
        System.out.println("They are not contained");

Please provide full function and how you are calling it for clarity — Sangharsh, Feb 15 '17 at 19:06
As @Coder pointed, add `if (firstWord.length == 0) return true;` as first condition. — Sangharsh, Feb 15 '17 at 19:10
@Sangharsh I had those checks in there I forgot to add them, just edited — Chris M, Feb 15 '17 at 19:11
I believe, you have issue in substring method. you should have like this : `return containedWordsCheck(firstWord.substring(1, firstWord.length()-1), secondWord, 0);` — Akash KC, Feb 15 '17 at 19:16
@LolCoder아카쉬 I noticed my code doesn't properly work now that I fixed the out of bounds exception, I tried adding the -1 like you suggested but now I get OutOfBounds: String index out of range: -1 — Chris M, Feb 15 '17 at 19:28

score 0 · Answer 1 · answered Feb 15 '17 at 19:11

Return if count is equal to the length of secondWord

public static boolean containedWordsCheck(String firstWord, String secondWord, int count) {
//Default rule for setting to false if the size of the first word is larger than the second
        if (firstWord.length() > secondWord.length() || count == secondWord.length())
            return false;
        //Default rule for setting to true if both strings are empty
        if (firstWord.isEmpty() && secondWord.isEmpty())
            return true;
        if (firstWord.charAt(0) == secondWord.charAt(count))
                    return containedWordsCheck(firstWord.substring(1, firstWord.length()), secondWord, 0);
        else if (firstWord.charAt(0) != secondWord.charAt(count) && count + 1 < secondWord.length())
                    return containedWordsCheck(firstWord, secondWord, count + 1);
        else
                    return false;

score 0 · Answer 2 · answered Feb 15 '17 at 19:12

The error indicates that you are attempting to execute charAt on an empty string. An empty string has no index 0, since it is empty. Just add a check to stop if the string is empty:

public static boolean containedWordsCheck(String firstWord, String secondWord, int count) {
    if (firstWord.length == 0)
        return false;
    //Default rule for setting to false if the size of the first word is larger than the second
    if (firstWord.length() > secondWord.length())
        return false;
    //Default rule for setting to true if both strings are empty
    if (firstWord.isEmpty() && secondWord.isEmpty())
        return true;
    if (firstWord.charAt(0) == secondWord.charAt(count))
                return containedWordsCheck(firstWord.substring(1, firstWord.length()), secondWord, 0);
    else if (firstWord.charAt(0) != secondWord.charAt(count) && count + 1 < secondWord.length())
                return containedWordsCheck(firstWord, secondWord, count + 1);
    else
                return false;
}

Thank you for the exception fix, unfortunately it seems my code doesn't work though. — Chris M, Feb 15 '17 at 19:30

Recursive method: StringIndexOutOfBoundsException

2 Answers2