Let all instances of object call method at same time (java)

June 27, 2022, at 08:00 AM

So I have a superclass called Tile and many subclasses like BlueTile, GreenTile etc..

All instances of the different subclasses are stored in an ArrayList (eg. (blueTile1, blueTile2, greenTile1....)).

There is a method called "activateTile()" in the superclass, that all subclasses use in a different way.

Now when I loop trough the array and activate all blue Tiles with blueTile.activateTile() they will be activated one after another right?

How can I let all blueTiles in the Array call the method at the same time? Or is there a way to simply say "all instances of that class, do that method now"?

Thank you :)

Answer 1

Unless you intend to launch a new Thread per instance, they will always being running methods sequentially.

Do you intend something like this?

void activateInParallel() {
    ArrayList<Thread> tileThreads = new ArrayList<>();
    for(Tile t : allTiles) {
        tileThreads .add(new Thread(()->t.activateTile()));
    }
    tileThreads.forEach(Thread::start);
}

I don't know enough details, but that is very likely not the best way to do it. I would consider using an Executor with a thread pool and offloading the work to it in a similar way.

    Executor executor = Executors.newFixedThreadPool(8);
    void activateInParallel() {
        for(Tile t : allTiles) {
            executor.execute(t::activateTile);
        }
    }