Introduction To Coroutines

What are Coroutines?

Coroutines are a powerful feature in Kotlin that simplify asynchronous programming. They allow developers to write code in a sequential manner while performing non-blocking operations. This means you can handle tasks like network calls, database access, or any operations that might take time without freezing the main thread.

Why Use Coroutines?

Coroutines offer several advantages over traditional asynchronous programming techniques such as callbacks or threads:

Simplicity: Code written with coroutines is often easier to read and maintain.
Lightweight: Coroutines are lighter than threads, allowing you to run thousands of coroutines without significant overhead.
Structured Concurrency: Coroutines help manage the lifecycle of tasks, making it easier to avoid memory leaks and manage exceptions.

Basic Coroutine Example

To use coroutines in Kotlin, you need to include the Kotlin Coroutines library in your project. Here’s a simple example:

First, add the dependencies in your build.gradle file:

implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.5.0'

Now, you can create a simple coroutine:

import kotlinx.coroutines.*

fun main() = runBlocking {
launch { // Launching a new coroutine
delay(1000L) // Non-blocking delay for 1 second
println("World!")
}
println("Hello, ")
}

Output:
Hello,
(after 1 second)
World!

Understanding Coroutine Builders

There are several coroutine builders provided by Kotlin:

runBlocking: Blocks the current thread until all coroutines inside are completed.
launch: Launches a new coroutine and immediately returns a reference to the coroutine without blocking the current thread.
async: Similar to launch, but it returns a Deferred object that represents a future result.

Example of Async Coroutine

Here’s an example using async to perform two tasks concurrently:

import kotlinx.coroutines.*

fun main() = runBlocking {
val deferred1 = async { doSomethingUsefulOne() }
val deferred2 = async { doSomethingUsefulTwo() }
println("The answer is ${deferred1.await() + deferred2.await()}")
}

suspend fun doSomethingUsefulOne(): Int {
delay(1000L)
return 13
}

suspend fun doSomethingUsefulTwo(): Int {
delay(1000L)
return 29
}

Output:
The answer is 42

Conclusion