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Anko Overview

Anko: A Kotlin Framework for Android Development.

Introduction​

Anko is an open-source Kotlin library developed by JetBrains that simplifies Android application development. It provides a set of utilities and DSLs (Domain Specific Languages) which eliminate boilerplate code and make Android development more concise and enjoyable.

Anko offers various features such as layout creation, asynchronous programming, SQLite database operations, and intents. Additionally, it seamlessly integrates with existing Android projects, allowing developers to mix Anko code with traditional Android code.

History​

The development of Anko started in 2015 with the aim of improving Android development in Kotlin. Kotlin is a modern programming language developed by JetBrains that is fully compatible with Java. By leveraging Kotlin's features, Anko simplifies many common Android tasks.

Features​

1. Layout Creation​

Anko provides a DSL for creating Android layouts programmatically, eliminating the need for XML layout files. This DSL allows you to define layouts using Kotlin code, making it easier to manipulate and customize UI elements.

verticalLayout {
    textView("Hello, Anko!")
    button("Click Me").setOnClickListener {
        // Handle button click
    }
}

In the above example, a vertical layout is created with a TextView displaying "Hello, Anko!" and a Button labeled "Click Me". The setOnClickListener function sets a click listener for the button.

2. Asynchronous Programming​

Anko simplifies asynchronous programming in Android by providing higher-order functions for executing code on different threads. It offers functions like doAsync and uiThread that allow you to perform background tasks and update the UI respectively.

doAsync {
    // Perform background task
    val result = fetchDataFromNetwork()

    uiThread {
        // Update UI with the result
        textView.text = result
    }
}

In the above example, doAsync executes the code block in a background thread, while uiThread updates the UI on the main thread. This helps prevent UI freezes and improves responsiveness.

3. SQLite Database Operations​

Anko provides a convenient DSL for working with SQLite databases. It simplifies tasks such as creating tables, inserting data, querying, and updating records.

database.use {
    createTable("Users", true,
        "id" to INTEGER + PRIMARY_KEY + AUTOINCREMENT,
        "name" to TEXT,
        "age" to INTEGER
    )

    insert("Users",
        "name" to "John",
        "age" to 25
    )

    val users = select("Users").parseList(classParser<User>())
}

In the above example, a table named "Users" is created with columns for id, name, and age. An entry is inserted into the table, and then a query is performed to retrieve all users. The classParser function is used to parse the query result into a list of User objects.

4. Intents​

Anko simplifies the creation of intents, making it easier to start activities and pass data between them.

val intent = intentFor<DetailActivity>("userId" to 1)
startActivity(intent)

In the above example, an intent is created for the DetailActivity class, and the "userId" extra is set to 1. The startActivity function is then used to start the activity.

Examples​

Example 1: Creating a Toast​

toast("Hello, Anko!")

The toast function displays a short-duration toast message with the specified text. In this example, "Hello, Anko!" is shown as a toast.

Example 2: Showing a Dialog​

alert("Are you sure?") {
    yesButton { toast("Confirmed") }
    noButton { toast("Cancelled") }
}.show()

The alert function creates a dialog with the specified message. It also allows you to add buttons and define their click listeners. In this example, a dialog with "Are you sure?" message is shown, and clicking the "Yes" button displays a toast with "Confirmed", while clicking the "No" button displays a toast with "Cancelled".

Example 3: Starting an Activity with Result​

button("Open Settings") {
    onClick {
        startActivityForResult<SettingsActivity>(SETTINGS_REQUEST_CODE)
    }
}

The startActivityForResult function starts an activity and expects a result. In this example, clicking the "Open Settings" button starts the SettingsActivity and waits for a result. The SETTINGS_REQUEST_CODE is a user-defined constant used to identify the request.

Conclusion​

Anko is a powerful Kotlin framework for Android development that simplifies common tasks and reduces boilerplate code. Its features such as layout creation, asynchronous programming, SQLite database operations, and intents make Android development more efficient and enjoyable. By using Anko, developers can write cleaner and more concise code, resulting in faster development and easier maintenance.

For more information, please visit the official Anko website: https://github.com/Kotlin/anko