Kotlin async func

To wait for a coroutine to finish, you can call Job. join . join is a suspending function, meaning that the coroutine calling it will be suspended until it is told to resume. At the point of suspension, the executing thread is released to any other available coroutines (that are sharing that thread or thread pool).

Coroutines are computer program components that generalize subroutines for non-preemptive multitasking, by allowing execution to be suspended and resumed . Coroutines are well-suited for implementing familiar program components such as cooperative tasks, exceptions, event loops, iterators, infinite lists and pipes.

runBlocking is a coroutine function . … Runs a new coroutine and blocks the current thread interruptible until its completion. This function should not be used from a coroutine. It is designed to bridge regular blocking code to libraries that are written in suspending style, to be used in main functions and in tests.

interface CompletableDeferred<T> : Deferred <T> A Deferred that can be completed via public functions complete or cancel.

Deferred value is a non-blocking cancellable future — it is a Job with a result. It is created with the async coroutine builder or via the constructor of CompletableDeferred class. It is in active state while the value is being computed.

Deferred represents a concept known by other names such as Future or Promise : it stores a computation, but it defers the moment you get the final result; it promises the result sometime in the future.