G7 verstaendlicher

String findLCS(String str1, String str2) {
    int longest = 0;
    String longestSubstring = "";

    for (int i=0; i < str1.length(); ++i) {
        for (int j=i+1; j <= str1.length(); ++j) {
            String substring = str1.substring(i, j);
            if (str2.contains(substring) && substring.length() > longest) {
                longest = substring.length();
                longestSubstring = substring;
            }
        }
    }

    return longestSubstring;
}