Java equivalent of C# Action.BeginInvoke

Question

I have this C# code:

Action action = MyFunction;
action.BeginInvoke(action.EndInvoke, action);

which, from what I can tell, just runs MyFunction asynchronously. Can you do the same thing in Java?

score 5 · Accepted Answer · answered Mar 12 '12 at 14:47

5

This is how you could run an action in its own thread in Java:

new Thread(new Runnable() {

    @Override
    public void run() {
        aFunctionThatRunsAsynchronously();
    }
}).start();

There are other higher-level frameworks available that give you more control on how things are run such as Executors, which can for example be used to schedule events.

answered Mar 12 '12 at 14:47

assylias

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`BeginInvoke` will use the thread pool, is there such a concept in Java? - Sorry, I should have taken a second to follow your "Executors" link! Thanks – weston Mar 12 '12 at 14:50
When I try this I get the error "The method run() of type new Runnable(){} must override a superclass method". – adam0101 Mar 12 '12 at 14:51
1

@adam0101 Not sure why: it works on my machine. What version of Java JDK are you using? If you use Java 5 or earlier, you might need to remove the `@Override` annotation (http://stackoverflow.com/questions/2135975/can-i-get-java-5-to-ignore-override-errors). – assylias Mar 12 '12 at 14:56

score 2 · Answer 2 · answered Mar 12 '12 at 14:52

Natively, the ExecutorService provides the closest I can think of. Here's how you can use the ExecutorService to run a method async and then get the return value later:

ExecutorService executor = Executors.newFixedThreadPool(NTHREDS);
Future<String> future = executor.submit(new Callable<String>() {
    return getSomeLongRunningSomethingHere();
});
//... do other stuff here
String rtnValue = future.get(); //get blocks until the original finishes running 
System.out.println(rtnValue);

score 1 · Answer 3 · edited May 23 '17 at 12:05

This is somewhat related to Asynchronous Event Dispatch in Java. Basically, you can structure the method you want to run as a class implementing Callable or Runnable. Java doesn't have the ability to refer to a "method group" as a variable or parameter, like C# does, so even event handlers in Java are classes implementing an interface defining the listener.

Try something like this:

Executor scheduler = Executors.newSingleThreadExecutor();

//You'd have to change MyFunction to be a class implementing Callable or Runnable
scheduler.submit(MyFunction);

Java equivalent of C# Action.BeginInvoke

3 Answers3