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Asynchronicity

Approaches for Asynchronous Programming​

There are two commonly used approaches for Asynchronous Programming as mentioned below:

1. Callbacks with CompletableFuture​

2. Asynchronous Programming with Future and ExecutorService​

1. Callbacks with CompletableFuture​

  • The CompletableFuture is a class introduced in Java 8 that facilitates asynchronous programming using the callback-based approach.
  • It represents a promise that may be asynchronously completed with the value or an exception.
//Java program to demonstrate the use of the CompletableFuture
import java.io.*;
import java.util.concurrent.CompletableFuture;

public class CF {

	public static void main(String[] args) {
		CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {
			try {
				Thread.sleep(200);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
			return "Hello, CompletableFuture!";
		});
		future.thenAccept(result -> System.out.println("The Result: " + result));
		try {
			Thread.sleep(300);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}
}

Output​

The Result: Hello, CompletableFuture!

2. Asynchronous Programming with Future and ExecutorService​

  • The Future and ExecutorService can be used for the asynchronous programming in a more traditional way.
  • The ExecutorService allows you to submit tasks for the asynchronous execution.
//Java program to demonstrate Asynchronous
// Programming with Future and ExecutorService
import java.io.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class FE {

	public static void main(String[] args) {
		ExecutorService executor = Executors.newSingleThreadExecutor();
		Future<String> future = executor.submit(() -> {
			try {
				Thread.sleep(200);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
			return "Hello, Future!";
		});
		try {
			String result = future.get();
			System.out.println("The Result: " + result);
		} catch (Exception e) {
			e.printStackTrace();
		}
		executor.shutdown();
	}
}

Output​

The Result: Hello, Future!