CompletableFuture已完成，但出现异常

CompletableFuture<Integer> future = CompletableFuture.completedFuture(42)
    .thenApply(i -> i / 0)
    .exceptionally(ex -> {
        System.out.println("Exception: " + ex);
        return 0;
    });

CompletableFuture<Integer> future = CompletableFuture.completedFuture(42)
    .thenApply(i -> i / 0)
    .handle((result, ex) -> {
        if (ex != null) {
            System.out.println("Exception: " + ex);
            return 0;
        } else {
            return result;
        }
    });

CompletableFuture<Integer> future = CompletableFuture.completedFuture(42)
    .thenApply(i -> i / 0)
    .whenComplete((result, ex) -> {
        if (ex != null) {
            System.out.println("Exception: " + ex);
        } else {
            System.out.println("Result: " + result);
        }
    });