Question

I’m trying to create a program in java where threads are observable objects and a window is the observer. What I don’t understand is how do I distinguish the several threads, which all do the same thing, from each other on the update method so that I could update their position individually on the window.

Answer 1

As Stated in comment by @PeterLawrey you can use the name argument from the Thread object to set an unique name and then query your Threads and find which one is doing what. The constructor is as follows:

public Thread(String name)
    Allocates a new Thread object. This constructor has the same effect as Thread (null, null, name).
Parameters:
    name - the name of the new thread

But, for accessing the Threads more easily after it’s executing, and to track I recommend the use of ThreadGroup object. From the api docs:

A thread group represents a set of threads. In addition, a thread group can also include other thread groups. The thread groups form a tree in which every thread group except the initial thread group has a parent.

Therefore, you can use the method public int enumerate(Thread[] list,
boolean recurse)

Which

Copies into the specified array every active thread in this thread group. If recurse is true, this method recursively enumerates all subgroups of this thread group and references to every active thread in these subgroups are also included. If the array is too short to hold all the threads, the extra threads are silently ignored.

And getName() of all threads in the group. I hope it helped. Cheers