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

In Kotlin coroutines, both launch and async are coroutine builders used to initiate the execution of coroutines. However, they serve different purposes and offer different mechanisms for handling coroutine execution and result retrieval.

• launch: The launch coroutine builder is used to launch a new coroutine asynchronously without returning a result. It starts the execution of a coroutine and returns a Job object, which can be used to control and manage the lifecycle of the coroutine.

kotlin

val job = CoroutineScope(Dispatchers.Default).launch {
 // Coroutine code
}

• async: On the other hand, the async coroutine builder is used to launch a new coroutine asynchronously and immediately returns a Deferred object that represents a future result of the coroutine computation. It allows you to perform asynchronous computation and retrieve the result at a later point in time.

kotlin

val deferred = CoroutineScope(Dispatchers.Default).async {
 // Coroutine code
 return@async result
}