What is the best way to make an async method call in Java?

General Discussions
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1

What is the best way to make an async method call in Java?

I’ve been exploring Go’s goroutines and wanted something similar in Java. From what I’ve found, the common way to parallelize a method call is by using:

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

But this approach doesn’t feel very elegant. Is there a better way to achieve this?

I actually needed an async method call in Java for a project, so I created my own wrapper class that allows calling methods asynchronously. My library, J-Go, makes it easy to do something like:

Go.with(obj).callLater("myRandomMethod");
// ... do other things
if (Go.lastResult().isReady()) {
    System.out.println("Method is finished!");
}

Internally, I use a Runnable implementation and reflection to invoke methods dynamically.

Is this approach safe? Is there already a simpler or more efficient way to handle Java async method calls? I’d love to hear opinions on my library and the overall best practices for asynchronous execution in Java.

2

In my experience, if you’re aiming for a simple and effective way to handle Java async calls, starting with ExecutorService is a solid bet. It offers cleaner thread management and is widely used in production setups.

:white_check_mark: Solution: ExecutorService (Cleaner Thread Management)

  • Automatically manages thread pooling.
  • Prevents the overhead of manually starting and managing threads.

:wrench: Code Example:

import java.util.concurrent.*;

ExecutorService executor = Executors.newSingleThreadExecutor();

Future<Boolean> future = executor.submit(() -> {
    return "somethingelse".matches("something");
});

// Perform other operations while async call executes

try {
    System.out.println("Result: " + future.get());  // Blocks until completion
} catch (Exception e) {
    e.printStackTrace();
}

executor.shutdown();

:bulb: Why Use This?

  • Efficient thread pooling.
  • Future<T> enables non-blocking retrieval of results.
  • Clean, reliable, and familiar in Java async programming.
3

@joe-elmoufak solution is great, but if you’re on Java 8 or later, there’s a more modern and flexible option: CompletableFuture. It makes Java async operations more readable and reactive."*

:white_check_mark: Try This: CompletableFuture (More Modern & Flexible)

:wrench: Code Example:

import java.util.concurrent.*;

CompletableFuture<Boolean> future = CompletableFuture.supplyAsync(() -> 
    "somethingelse".matches("something")
);

// Continue with other tasks

future.thenAccept(result -> 
    System.out.println("Result: " + result)  // Executes when the result is ready
);

:rocket: Why It’s Better:

  • Non-blocking: thenAccept() executes when the task finishes.
  • Chainable: Combine multiple async operations using thenApply(), thenCombine(), etc.
  • Built-in (Java 8+): No need for external libraries.
  • Cleaner Code: Simplifies async Java programming significantly.
4

@sam.aarun makes a great point with CompletableFuture, but if you’re working with Java 19 or later, there’s an even better option: virtual threads. These offer lightweight concurrency similar to Go’s goroutines."*

:white_check_mark: Next-Level Solution: Virtual Threads (Java 19+, Super Lightweight)

Key Benefits:

  • Ultra-lightweight threads with minimal overhead.
  • Highly scalable for massive async Java operations.
  • Perfect for I/O-bound or high-concurrency tasks.

:wrench: Code Example:

Thread.startVirtualThread(() -> {
    System.out.println("Running in a virtual thread!");
});

:bulb: Why Choose This?

  • Minimal Resource Usage: Virtual threads consume fewer resources than OS threads.
  • Scales Efficiently: Great for handling a large number of concurrent Java async tasks.
  • Closer to Go’s Goroutines: Offers goroutine-like performance and simplicity.