What is the difference between launch and async functions when using coroutines in Kotlin?

The launch and async functions in Kotlin are used to start coroutines but serve different purposes and return different types.

• launch starts a coroutine that runs in the background and does not return a result. It returns a Job object, which can be used to control the coroutine (e.g., cancel it).

• async starts a coroutine that returns a result in the future. It returns a Deferred<T> object, which is a subclass of Job and allows obtaining the result via await().

Example:

val job = scope.launch {
    // perform a task without a result
}

val deferred = scope.async {
    // compute and return a result
    42
}

runBlocking {
    val result = deferred.await() // get the result
    println(result) // 42
}

Summary:

• Use launch when no result is needed.
• Use async when you need to get the result of an asynchronous operation.