CompletableFuture.java

// when there is no return value
CompletableFuture<Void> future2 = CompletableFuture.runAsync(() -> {
    System.out.println("Hello "+ Thread.currentThread().getName());
});
future2.get(); // get() should be called to execute the thread


// when there is a return value
CompletableFuture<String> future3 = CompletableFuture.supplyAsync(() -> {
    System.out.println("HEllo " + Thread.currentThread().getName());
    return "Hello";
});
System.out.println(future3.get());