How can you check multiple index using charAt() method in java?

I am trying to compare two string-arrays from a .txt file input based on the index of a char.

So String1[i] is not complete -> example: B_nana.

String2[j] is the fitting word for string 1 -> Banana

If the program finds a matching index, for example -> both have "a" at index 1, it checks for the string length and if that matches aswell it replaces String1[i] = String2[j].

But everytime the charAt() index exceeds the length of a string while comparing (one of the strings is shorter than the other), I get StringOutOfBoundException.

So my question is, is there any way to compare not only one index of two strings but all of them?
I already tried using

string.substring(0, str.length -1) but thats not working at all.

Grateful for any suggestions and if you need more information to answer my question please feel free to say so.

Based on your comment, I would do the following:

1. Build a list of valid words (List<String> knownWords)
2. Build a list of words with gaps (List<String> guessWords)

Here is some pseudo code

• For each word in guessWords:
  • while (!match && has more words in knownWords)
    • set match to false
    • compare the length of the current guess word to the nth word in know words
    • if they have the same length, compare each character. If each character from the known word is equal to each character of the guess word or if the guess word's character is _ then match = true

This should put you on the right track

Sample source code (Java)

package eu.webfarmr;

/**
 * This class takes in 2 lists (or arrays) and tries to match words from the first array to words in the second
 * the underscore (_) is considered to be a missing letter.
 * @author dbrossard
 *
 */
public class WordMatcher {
	private final static String[] knownWords = {"apple", "arcane", "batter", "butter", "banana"};
	private final static String[] guessWords = {"a___e","a____e","__tte_","b_____"};
	public static void main(String[] args) {
		for (String guessWord : guessWords) {
			boolean matchFound = false;
			int i = 0;
			while (!matchFound && i < knownWords.length) {
				if (guessWord.length()==knownWords[i].length()) {
					int j = 0;
					while (j < guessWord.length() && (guessWord.charAt(j)==knownWords[i].charAt(j) || guessWord.charAt(j)=='_') ) {
						j++;
					}
					matchFound = (j == guessWord.length());
					if (matchFound) {
						System.out.println(guessWord + " matches " + knownWords[i]);
					}
				}
				i++;
			}
		}
	}
}

If you want to find all matches and not just the first one change while (!matchFound && i < knownWords.length) { to while (i < knownWords.length) {.

Here is sample output:

a___e matches apple
a____e matches arcane
__tte_ matches batter
__tte_ matches butter
b_____ matches batter
b_____ matches butter
b_____ matches banana