CompletableFuture

What is CompletableFuture?

• Supports asynchronous programming in Java

• A class that implements Future and CompletionStage

  • What is Future?

    • A class that represents the result of an asynchronous operation

      • It allows you to know the result of a scheduled task

    • It can pass processed data to another thread in a multi-thread environment

    • Since it is implemented as Thread-Safe internally, there is no need to use synchronized blocks

• It makes the following tasks, which were difficult with Future, much easier

  • A Future cannot be completed externally

    • You cannot cancel it or set a timeout on get()

  • Without using blocking code (get()), you cannot execute a callback when the task finishes

    • Any work that creates a result value through a Future and does something with it must come after get()

  • Multiple Futures cannot be combined

    • ex) Fetching event information and then fetching the list of members who participated in the event

  • It does not provide an API for exception handling