Design pattern to handle an asynchronous response in Java

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Answer 1

Could CountDownLatch help you? In the main method, you call getResponse and then countDownLatch.await(). Pass a count down latch to the getResponse method and then count down once getResponse the result from getResponse is finished:

CountDownLatch latch = new CountDownLatch(1);
Response a = getResponse(latch);
latch.await();

latch = new CountDownLatch(1);
Response b = getResponse(latch);
latch.await();

process(a, b);

Your getResponse needs to call latch.countDown() once it's asynch parts return a result.

e.g.:

public Response getResponse(CountDownLatch latch) {
     someAsychBloc(final CountDownLatch latch) {
       do work
       latch.countDown();
    }
}