KMP string-matching algorithm implementation

Question

This is Knuth-Morris-Prat algorithm implementation to check if a pattern is present in a larger text, and if it does the algorithm returns the start index of that pattern, else -1. It starts off by computing Longest Common Prefix array, please refer LCP array, and uses that to efficiently avoid redundant pattern matching. I request that my code be reviewed for implementation and naming conventions. For more context about the question please refer, StrStr()

int knuthMorrisPratt(String text, String pattern) {
    if (text == null || pattern == null || text.length() < pattern.length) {
        return -1;
    }
    if (pattern.length() == 0) {
        return 0;
    }
    int[] lcp = computeLongestCommonPrefixArray(pattern);
    int i = 0, j = 0;
    while (i < text.length() && j != pattern.length()) {
        if (text.charAt(i) == pattern.charAt(j)) {
            j++;
        }
        else {
            if (j > 0) {
                j = lcp[j - 1];
                continue;
            }
        }
        i++;
    }
    return (i - j) <= (text.length() - pattern.length()) ? (i - j) : -1;
}

int[] computeLongestCommonPrefixArray(String pattern) {
    int[] lcp = new int[pattern.length()];
    int len = 0, i = 1;
    while (i < pattern.length()) {
        if (pattern.charAt(i) == pattern.charAt(len)) {
            len++;
            lcp[i] = len;
            i++;
        }
        else {
            if (len != 0) {
                len = lcp[len - 1];
            }
            else {
                lcp[i] = 0;
                i++;
            }
        }
    }
    return lcp;
}