Try monad in Java 8

Question

Is there a built-in support for monad that deals with exception handling? Something similar to Scala\'s Try. I am asking because I don\'t like unchecked exceptions.

Answer 1

You can do what you want by (ab)using CompletableFuture. Please don't do this in any sort of production code.

CompletableFuture sc = CompletableFuture.completedFuture(
                                                      new Scanner(System.in));

CompletableFuture divident = sc.thenApply(Scanner::nextInt);
CompletableFuture divisor = sc.thenApply(Scanner::nextInt);

CompletableFuture result = divident.thenCombine(divisor, (a,b) -> a/b);

result.whenComplete((val, ex) -> {
    if (ex == null) {
        System.out.printf("%s/%s = %s%n", divident.join(), divisor.join(), val);
    } else {
        System.out.println("Something went wrong");
    }
});