Java - fire action after specific Thread has ended [duplicate]

Question

This is my code:

Thread T = new Thread() {
    public void run() {
        //some code here...
    }
};
T.start();

I need to know when this specific thread has finished so I can start another code right afterwards, something like this hypothetical option:

T.finished(){
    //some code here
}

EDIT: the solution provided by @swpalmer is the most straightforward and the easiest compared to all the other ones, I would not consider this being a duplicate as the accepted solution is different to the others and is really extremely easy to implement, yet doing what it should and what I was asking for!

Answer 1

Here:

 public void run() {
    //some code here...
    whatever.finished();
 }

That is the straight forward way of solving this: your last action in your thread is to send that "event".

Sure, you can also use Thread.join() to do that from the outside.

Answer 2

Instead of Thread, consider using java.util.concurrent.CompletionStage

You can chain together actions using whenComplete() or one of the other methods.

See examples here

    CompletableFuture.runAsync(() -> {
        //some code here...
        System.out.println("Hi!");
    }).thenRun(() -> {
        //some code here
        System.out.println("Greeting completed");
    });