Validation Filter

public static String filter(String value) {
    if (value == null) {
        return null;
    }
    StringBuilder result = new StringBuilder(value.length());
    for (int i = 0; i < value.length(); ++i) {
        switch (value.charAt(i)) {
            case '<':
                result.append("<");
                break;
            case '>':
                result.append(">");
                break;
            case '"':
                result.append(""");
                break;
            case '\'':
                result.append("'");
                break;
            case '%':
                result.append("%");
                break;
            case ';':
                result.append(";");
                break;
            case '(':
                result.append("(");
                break;
            case ')':
                result.append(")");
                break;
            case '&':
                result.append("&");
                break;
            case '+':
                result.append("+");
                break;
            default:
                result.append(value.charAt(i));
                break;
        }
    }
    return result;
}