Java · Senior · Coding

There are price providers, and each one has a price method that takes a SKU and asynchronously returns a CompletableFuture with a price. Write a method bestPrice that takes a SKU and a list of providers, queries all of them in parallel, and returns a CompletableFuture with the lowest price: providers that fail or don't respond within two seconds are skipped, and if nobody returned a price, the result completes with an error.

~15 min by voice

How to approach it

They're checking whether you can build a non-blocking composition of CompletableFutures: a parallel fan-out, a timeout and error isolation for each call, aggregation via allOf, and correct handling of an empty result with an exception rather than null.

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Topics

completable future async

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Answer by voice

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