A.java

public static String escapeString(Object o) {
    if (o == null) {
        return null;
    }
    String str = o.toString();
    if (str.contains("\\")) {
        str = str.replace("\\", "\\\\");
    }
    if (str.contains("\"")) {
        str = str.replace("\"", "\\\"");
    }
    return str;
}