Question

Will java.util.UUID work for classes in Java? That is to say i have a class that requires a unique id such that each time i construct an object of that class inside the main method, it will have a unique ID number.

the constructor might look something like this:

class flight{
        private UUID id;

        public void flight(){
           id = UUID.randomUUID();
        }
}

and the main method call might look something like this:

public static void main(String[] args){
    flight[] allflights = new flight[100];
    flight tempFlight;

    for(int i=0; i<100; i++){
        tempFlight = new flight()
        allflights[i] = tempFlight;
    }

Will this generate a unique ID for all the flights inside the flight array?

Answer 1

Yes, this is what UUIDs are for. You’ll get a new random UUID every time you call randomUUID() ; a UUID is a 128bit value.

So theoretically you could get collisions when using random UUIDs, but as it says that a cryptographically strong random generator is used i don’t think you need to bother with that possibility.