Hands-On High Performance with Spring 5

@Async with CompletableFuture

In the previous section, we saw how we can use java.util.Future to get the result of asynchronous method execution. It provides an isDone() method to check whether the computation is done or not, and a get() method to retrieve the result of the computation when it is done. But there are certain limitations to using the Future API:

• Suppose we have written code to fetch the latest product price from an e-commerce system through a remote API. This task is time-consuming, so we need to run it asynchronously and use Future to get the result of that task. Now, the problem will occur when the remote API service is down. At that time, we need to complete Future manually by the last cached price of the product and that ...