How to asynchronously call a method in Java

user_40876 0
Viewed 381805

I've been looking at Go's goroutines lately and thought it would be nice to have something similar in Java. As far as I've searched the common way to parallelize a method call is to do something like:

final String x = "somethingelse";
new Thread(new Runnable() {
           public void run() {
                x.matches("something");             
    }
}).start();

Thats not very elegant. Is there a better way of doing this? I needed such a solution in a project so I decided to implement my own wrapper class around a async method call.

I published my wrapper class in J-Go. But I don't know if it is a good solution. The usage is simple:

SampleClass obj = ...
FutureResult<Integer> res = ...
Go go = new Go(obj);
go.callLater(res, "intReturningMethod", 10);         //10 is a Integer method parameter
//... Do something else
//...
System.out.println("Result: "+res.get());           //Blocks until intReturningMethod returns

or less verbose:

Go.with(obj).callLater("myRandomMethod");
//... Go away
if (Go.lastResult().isReady())                //Blocks until myRandomMethod has ended
    System.out.println("Method is finished!");

Internally I'm using a class that implements Runnable and do some Reflection work to get the correct method object and invoking it.

I want some opinion about my tiny library and on the subject of making async method calls like this in Java. Is it safe? Is there already a simplier way?

goroutine concurrency asynchronous java
12 Answers

Java 8 introduced CompletableFuture available in package java.util.concurrent.CompletableFuture, can be used to make a asynch call :

CompletableFuture.runAsync(() -> {
    // method call or code to be asynch.
});
user_48597370

Java also provides a nice way of calling async methods. in java.util.concurrent we have ExecutorService that helps in doing the same. Initialize your object like this -

 private ExecutorService asyncExecutor = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors());

and then call the function like-

asyncExecutor.execute(() -> {

                        TimeUnit.SECONDS.sleep(3L);}
user_109047240

There is also nice library for Async-Await created by EA: https://github.com/electronicarts/ea-async

From their Readme:

With EA Async

import static com.ea.async.Async.await;
import static java.util.concurrent.CompletableFuture.completedFuture;

public class Store
{
    public CompletableFuture<Boolean> buyItem(String itemTypeId, int cost)
    {
        if(!await(bank.decrement(cost))) {
            return completedFuture(false);
        }
        await(inventory.giveItem(itemTypeId));
        return completedFuture(true);
    }
}

Without EA Async

import static java.util.concurrent.CompletableFuture.completedFuture;

public class Store
{
    public CompletableFuture<Boolean> buyItem(String itemTypeId, int cost)
    {
        return bank.decrement(cost)
            .thenCompose(result -> {
                if(!result) {
                    return completedFuture(false);
                }
                return inventory.giveItem(itemTypeId).thenApply(res -> true);
            });
    }
}
user_33560280
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