How to ensure thread safety of utility static method?

Question

Is there any general way or rules exits by which we can ensure the thread safety of static methods specifically used in various Utility classes of any applications. Here I w

Answer 1

I would recommend creating a copy of that (mutable) object as soon as the method starts and use the copy instead of original parameter.

Something like this

public static Date getNormalizeDate(Date date) {
    Date input = new Date(date.getTime());
    // ...
}