promise sample java

Here is a sample Java code for Promise:

import java.util.concurrent.CompletableFuture;

public class PromiseExample {
    public static void main(String[] args) {
        CompletableFuture<String> promise = new CompletableFuture<>();
        
        // Set the promise value after 2 seconds
        new Thread(() -> {
            try {
                Thread.sleep(2000);
                promise.complete("Promise Fulfilled!");
            } catch (InterruptedException e) {
                promise.completeExceptionally(e);
            }
        }).start();
        
        // Wait for the promise to be fulfilled
        promise.thenAccept(value -> {
            System.out.println(value);
        }).join();
    }
}

In this example, we create a CompletableFuture object named promise. We then start a new thread that waits for 2 seconds before setting the promise value to "Promise Fulfilled!". We then use the thenAccept method to wait for the promise to be fulfilled and print the value when it is fulfilled. Finally, we use the join method to wait for the promise to be fulfilled before exiting the program.