What does 'result' in ExecutorService.submit(Runnable task, T result) do?

Question

Looking at the javadocs it just says

Future submit(Runnable task, T result)

Submits a Runnable task for executio

Answer 1

You can mutate the object that was passed-in during the task. For example:

final String[] mutable = new String[1];
Runnable r = new Runnable() {
    public void run() {
        mutable[0] = "howdy";
    }
};
Future f = executorService.submit(r, mutable);
String[] result = f.get();
System.out.println("result[0]: " + result[0]);

When I run this code it outputs:

result[0]: howdy