Anko: A Powerful Library for Android Development in Kotlin

Anko is an open-source library developed by JetBrains for simplifying Android application development using Kotlin. The library provides a set of extensions, functions, and types that make Android programming more concise and expressive. In this article, we’ll explore the various features of Anko and see how it can be used to build a simple Android app.

Getting Started with Anko

To start using Anko in your Android project, add the following dependencies to your build.gradle file:

dependencies {
    implementation 'org.jetbrains.anko:anko-commons:0.10.8'
    implementation 'org.jetbrains.anko:anko-sdk27:0.10.8'
    implementation 'org.jetbrains.anko:anko-appcompat-v7:0.10.8'
    implementation 'org.jetbrains.anko:anko-design:0.10.8'
}

These dependencies bring in the core Anko library, along with support for various Android SDK and AppCompat versions. You can replace the version numbers with the latest available versions from the Anko GitHub repository.

Anko Layouts

Anko Layouts is a feature that allows you to create Android UI layouts using Kotlin code instead of XML. This approach provides several benefits, including better compile-time type checking, more expressive layouts, and easier refactoring.

To create a layout with Anko, you can define a subclass of AnkoComponent and implement the createView method. Here’s a simple example:

class MainActivityUI : AnkoComponent<MainActivity> {
    override fun createView(ui: AnkoContext<MainActivity>): View = with(ui) {
        verticalLayout {
            val name = editText {
                hint = "Enter your name"
            }
            button("Say Hello") {
                onClick { ctx.toast("Hello, ${name.text}!") }
            }
        }
    }
}

In this example, we create a simple UI consisting of an EditText and a Button arranged in a vertical layout. The createView method takes an AnkoContext parameter, which is used to create the layout and access the parent activity.

To use this layout in an activity, just call the setContentView method with an instance of the AnkoComponent:

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        MainActivityUI().setContentView(this)
    }
}

Anko Commons

Anko Commons is a collection of utility functions and extensions that simplify common Android tasks, such as working with intents, dialogs, and logging.

For example, the following code demonstrates how to use Anko Commons to start a new activity with an intent:

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        MainActivityUI().setContentView(this)

        button("Open Details Activity") {
            onClick {
                startActivity<DetailsActivity>("key" to "value")
            }
        }
    }
}

In this example, the startActivity function is provided by Anko Commons and allows you to start a new activity with a concise syntax. The to function creates a Pair, which can be used to pass data to the target activity.

Anko Commons also provides functions to create dialogs and toasts with a more expressive syntax:

button("Show Dialog") {
    onClick {
        alert("This is an Anko dialog", "Anko Dialog") {
            yesButton { toast("You clicked Yes!") }
            noButton { toast("You clicked No!") }
        }.show()
    }
}

Conclusion

Anko is a powerful library for simplifying Android development with Kotlin. It offers a more expressive and concise syntax for creating layouts, working with intents, and handling other common tasks. By leveraging Anko’s features, you can create cleaner and more maintainable Android applications.