How to handle exception of CompletableFuture get() method

I need to to send requests to 3rd party urls so i used @Async on getStatus() method which returns CompletableFuture of enum and if TimeoutException is thrown i'd like to consider status as DOWN or how to catch InterruptedException and ExecutionException of each call

try {
    firstAppStatus = service1.getStatus().get(20, TimeUnit.SECONDS);
} catch (TimeoutException e) {
    firstAppStatus = ComponentStatusEnum.DOWN;
}
try {
    secondAppStatus = service2.getStatus().get(20, TimeUnit.SECONDS);
} catch (TimeoutException e) {
    secondAppStatus = ComponentStatusEnum.DOWN;
}
try {
    thirdAppStatus = service3.getStatus().get(20, TimeUnit.SECONDS);
} catch (TimeoutException e) {
    thirdAppStatus = ComponentStatusEnum.DOWN;
}

I know this code will executed sequentially so how run them asynchronous with this behavior without making changes on client request timeout

If I understand you correctly, you want something like this:

// allow all three requests to run concurrently
CompletableFuture<ComponentStatusEnum> status1 = service1.getStatus();
CompletableFuture<ComponentStatusEnum> status2 = service2.getStatus();
CompletableFuture<ComponentStatusEnum> status3 = service3.getStatus();

// wait for either, the completion of all three or the timeout, whatever comes first
try {
    CompletableFuture.allOf(status1, status2, status3).get(20, TimeUnit.SECONDS);
} catch(TimeoutException|InterruptedException|ExecutionException ex) {
    // no action, as all cases are handled below
}

// get results with fall-backs on timeout
firstAppStatus  = status1.getNow(ComponentStatusEnum.DOWN);
secondAppStatus = status2.getNow(ComponentStatusEnum.DOWN);
thirdAppStatus  = status3.getNow(ComponentStatusEnum.DOWN);

First, do not query the results immediately if you want to allow all requests to run in parallel. Then, using allOf, you can wait for the completion of all operations with a single timeout.

getNow is the right operation to get the result immediately when available or the specified fall-back value if the operation has not completed yet. In principle, it’s possible that the operation completes in the small time window between getting a TimeoutException and calling getNow, but this should not create any problem for your application logic.

Regarding exception handling, getNow behaves like join() throwing an unchecked CompletionException instead of the checked ExecutionException when the underlying operation failed. If you don’t catch it, it gets propagated to the caller, which is the best option if you have no special handling for this case. If the waiting with timeout got interrupted, it will behave just as if you had a smaller timeout; the operations might have finished already or get the fall-back value at getNow.

With Java 9 you can use completeOnTimeout:

CompletableFuture<ComponentStatusEnum> firstAppStatus = service1.getStatus().completeOnTimeout(ComponentStatusEnum.DOWN, 20, TimeUnit.SECONDS);

More info here.