Learn Kotlin Coroutines for Android Development

Get Started with Kotlin Coroutines for Android Development

Learn how to use Kotlin Coroutines for Android development. This tutorial will teach you how to create asynchronous programming with coroutines, manage background tasks, and more.

Kotlin coroutines are a powerful tool for asynchronous programming in Android. They allow developers to write asynchronous code in a more concise and readable way.

Credit: Github Kotlin Coroutines

What is Kotlin Coroutines?

If you’re new to Kotlin, you might be wondering what coroutines are and how they can help your app. Kotlin Coroutines are a new language feature in Kotlin 1.3 that allows you to run Kotlin code asynchronously. Coroutines allows us to suspend and resume the execution of our API calls asynchronously. This means that we can create asynchronous calls without having to worry about blocking each other on the main thread (i.e., the one used by your application).

Coroutines also allow us to manage thread creation and execution of code on those threads—so long as it doesn't block anyone else from doing anything else!

Why use Kotlin Coroutines?

Coroutines are useful in many situations where you want to use an asynchronous function and pass it as a parameter to another synchronous function. In fact, coroutines were originally introduced as an alternative to callbacks in Java, which was notoriously difficult to write cleanly and maintain.

Coroutines are a great way to write asynchronous code, with the added benefit of being easy to read and maintain. Kotlin provides the building block for asynchronous programming with a single construct: the suspend keyword, along with a bunch of library functions that make it shine.

How to use Kotlin Coroutines on Android

You now know what Kotlin Coroutines are, but how can you start using them?

Let's say we have an app that needs to fetch some data from an API and display it in a list. We want to do this asynchronously so that the UI remains responsive while the data is being fetched. Here's how we could use coroutines to achieve this:

1. Add the Coroutines dependency to your Android project.

You can add it to your app-level build.gradle file like this:

dependencies { 
    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:1.6.0" 
    implementation "androidx.lifecycle:lifecycle-runtime-ktx:1.6.0" 
}

2. Define a suspend function to fetch the data

Next, we'll define a function to fetch the data using coroutines:

suspend fun fetchData() : List<Data> = withContext(Dispatchers.IO) {
    // Make a network request to fetch the data
    val response = apiService.getData()
    // Convert the response to a list of Data objects
    val data = response.items.map { item -> Data(item.id, item.title, item.description) }
    // Return the data
    data
}

In this function, we're using the withContext function to switch to the IO coroutine dispatcher. This is because we're making a network request, which is an I/O operation that should be performed off the main thread. Once we have the data, we convert it to a list of Data objects and return them.

3. Fetch the data using lifecycleScope

Now, we can use this function in our activity to fetch the data and display it in a list:

class MainActivity : AppCompatActivity() {

    private val adapter = DataAdapter()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // Set up the RecyclerView
        recyclerView.layoutManager = LinearLayoutManager(this)
        recyclerView.adapter = adapter

        // Fetch the data
        lifecycleScope.launch {
            val data = fetchData()
            adapter.setData(data)
        }
    }
}

In the onCreate method, we're setting up a RecyclerView to display the data, and then use a coroutine to fetch the data and set it on the adapter. 

We're using the lifecycleScope provided by the androidx.lifecycle:lifecycle-runtime-ktx library to launch the coroutine. This ensures that the coroutine is canceled when the activity is destroyed, which helps avoid memory leaks.

Overall, using coroutines in Android allows us to write cleaner, more concise code for asynchronous operations. By using the suspend keyword and the withContext function.

We hope that this post has given you a good introduction to Kotlin Coroutines. These can be used for asynchronous programming in Android, and they’re very easy to understand once you get them down! 

Reference :

• https://github.com/Kotlin/kotlinx.coroutines