Multithreading: CompletableFuture.thenCombine joins two futures

thenCombine runs a function over the results of two independent CompletableFutures once both have completed, without either one having to wait for the other to start. The combining function itself only runs after both async computations are done.

Code

CompletableFuture<Integer> a = CompletableFuture.supplyAsync(() -> 6);
CompletableFuture<Integer> b = CompletableFuture.supplyAsync(() -> 7);
CompletableFuture<Integer> combined = a.thenCombine(b, (x, y) -> x * y);
System.out.println("Combined result: " + combined.get());

Output

Combined result: 42