Java implementation of HTML highlighter. Replaces found query tokens in target strings for their HTML bolded version, keeping the original case of the token.

simpleHTMLHighliter.java

    static String simpleHTMLHighlighter(String query, String str) {
        if (query == null || query.isEmpty()) {
            return str;
        }

        // Get unique tokens in the query
        String[] rawTokens = query.split("\\s+");
        HashSet<String> uniqueTokens = new HashSet<>();
        for (String token : rawTokens) {
            uniqueTokens.add(token.trim());
        }

        // Replace all instances of unique tokens for bolded versions in original string
        for (String token : uniqueTokens) {
            // find case insensitive regions where our token could be
            int offset=0;
            int regionEnd = offset + token.length();
            while (regionEnd < str.length()) {
                if (str.regionMatches(true, offset, token, 0, token.length())) {
                    String tokenAsFoundInStr = str.substring(offset, offset + token.length());
                    str = str.substring(0, offset) + "<b>" + tokenAsFoundInStr + "</b>" +
                          str.substring(offset + token.length());
                    offset += token.length() + 7;
                } else {
                    offset += 1;
                }
                regionEnd = offset + token.length();
            }
        }

        return str;
    }