Kotlin Coroutines Android

Introduction

Kotlin Coroutines Android have gained significant traction in Android development due to their robustness and widespread adoption. They offer a streamlined and efficient solution for implementing asynchronous programming patterns. By leveraging suspending functions and structured concurrency, coroutines enable developers to write non-blocking code that can be paused and resumed at specific points. This approach eliminates the need for callbacks or separate threads traditionally used in Android asynchronous programming.

The main advantage of Kotlin Coroutines Android lies in its ability to enhance the responsiveness and performance of Android applications. Lengthy operations, such as network requests and database queries, can be executed in the background without blocking the main thread. This ensures a smooth user experience and prevents UI freezes. Kotlin Coroutines Android provides an intuitive and sequential programming model, allowing developers to write code that appears synchronous while executing asynchronously in the background.

Prerequisites

It's crucial to grasp asynchronous programming and the fundamentals of the Kotlin programming language before going into Kotlin Coroutines in Android development. It's also advised to be familiar with the Android Studio IDE.

Understanding of Asynchronous Programming in Android

Asynchronous programming enables lengthy activities to be carried out in the background without obstructing the main thread, making it a crucial ability for Android developers. This may enhance the app's functionality and responsiveness, which will enhance the user experience. Among other techniques, asynchronous programming on Android may be accomplished by using threads, callbacks, or RxJava.

Basic Knowledge of Kotlin Programming Language

Working with Kotlin Coroutines also requires a basic understanding of the Kotlin programming language. Modern, succinct, expressive, and built to replace Java, Kotlin is a programming language. It has achieved great acceptance in the Android community and is currently the recommended language for Android development. Kotlin's core features include lambdas, coroutines, extension functions, null safety, and lambda expressions.

Familiarity with Android Studio IDE

Working with Kotlin Coroutines also calls for familiarity with the Android Studio IDE. The official IDE for Android development, Android Studio, offers a variety of strong capabilities for creating, testing and debugging Android applications. Code completion, debugging tools, and the Android Emulator for testing apps on virtual devices are some of the main features of Android Studio.

Two Types of Coroutines

Why do we Need Coroutines?

• Simpler and more readable code:
  Coroutines enable programmers to write asynchronous code in a more organized and sequential manner without the need for callbacks or intricate synchronization. This can reduce the likelihood of problems and make it simpler to maintain the code over time by making it easier to read and comprehend.
• Improved performance:
  Coroutines are faster to build and delete than threads and consume less memory, making them more efficient than threads. Particularly in mobile and online apps where resources are scarce, this may result in quicker performance and less resource utilization.
• Simplified error management:
  Coroutines offers an organized method of managing mistakes, which makes it simpler to manage and spread faults throughout the program. As a result, the application's overall quality may increase and the likelihood of crashes may be decreased.
• Support for complicated activities:
  Coroutines offer a versatile and effective means of managing complex operations, such as lengthy processes or processes that need synchronization. As a result, writing scalable and efficient code may be simpler.
• Better integration with other modern programming techniques:
  Coroutines are meant to integrate more effectively with other contemporary programming paradigms, including reactive programming and functional programming. This can make it simpler to use other cutting-edge programming techniques and incorporate coroutines into current codebases.

Features

Lightweight:

Kotlin Coroutines Android is more efficient and consumes fewer system resources than traditional threading methods, reducing unnecessary context switching and improving performance. They are ideal for resource-constrained mobile and online apps.

Fewer Memory Leaks:

Kotlin Coroutines Android provides a structured approach to memory management. They are associated with a specific scope, ensuring they are terminated upon scope destruction, reducing the risk of memory leaks compared to traditional thread management.

Built-in Cancellation Support:

Kotlin Coroutines Android has built-in support for cancellation, simplifying the management of long-running tasks that need to be stopped. This ensures that resources are freed and the coroutine is terminated when canceled, reducing the risk of crashes.

Jetpack Integration:

Kotlin Coroutines Android is integrated with Android's Jetpack, providing developers with tools and libraries (e.g., LiveData, ViewModel, Room) that work seamlessly with Coroutines, speeding up Android app development.

Main Thread Safety:

Kotlin Coroutines Android is designed to be main-thread safe, allowing developers to perform asynchronous tasks without blocking the main thread. This is crucial for a responsive user experience, as it ensures that the main thread remains available for user interactions and other events. Coroutines achieve this through non-blocking suspend functions.

Kotlin Coroutines vs Threads

Advantages of Kotlin Coroutines over Threads:

• Lightweight:
  Coroutines written in Kotlin are faster and more efficient than threads because they are less in weight and utilize fewer system resources. Coroutines prevent idly moving between contexts, which can save memory and boost efficiency.
• Structured Concurrency:
  Kotlin Coroutines Android provides a structured concurrency model, which makes it easier to manage and control asynchronous operations. Coroutines are associated with a specific scope, and when the scope is destroyed, any associated coroutines are automatically canceled. This helps to avoid memory leaks and makes it easier to manage long-running tasks.
• Built-in Cancellation Support:
  Kotlin Coroutines Android has built-in cancellation support, which makes it easier to handle long-running tasks and operations that need to be canceled. When a coroutine is canceled, any resources associated with it are automatically released, which helps to avoid memory leaks and other issues.

Compared to Threads, Kotlin Coroutines have the following drawbacks:

• Learning Curve:
  Because Kotlin coroutines have a steeper learning curve than threads, developers who are unfamiliar with asynchronous programming may find it more challenging to utilize them. The programming model for coroutines is distinct from that of threads, therefore knowledge of suspend functions, coroutines, and the coroutine context is necessary.
• Compatibility:
  Because not all libraries and frameworks are compatible with Kotlin coroutines, their use in specific situations may be constrained. Utilizing coroutines, for instance, may require additional settings in various libraries and frameworks.

Advantages of Threads over Kotlin Coroutines:

• Compatibility:
  Threads are more adaptable than other asynchronous programming options since they function with a broad variety of libraries and frameworks. Almost any concurrency-supporting library or framework can utilize threads.
• Familiarity:
  Threads are easy to use and comprehend since they are a known programming model to many engineers. It could be simpler for developers to utilize threads than to learn a new programming paradigm like coroutines if they are already accustomed to using them.

Compared to Kotlin Coroutines, Threads has the following drawbacks:

• Overhead:
  Coroutines have lower overhead than threads, which can lead to faster performance and less resource utilization. It can be costly to move between threads of execution, particularly on mobile devices with constrained resources.
• Error-Prone:
  Threads are prone to errors and, if not used properly, can result in problems like deadlocks, race situations, and memory leaks. These problems can cause crashes and other problems in the program, and they can be challenging to detect and resolve.

Kotlin Coroutines Example

We'll be creating a weather app that shows the current temperature in a specific place. Coroutines will be used to manage network requests and UI modifications while the OpenWeatherMap API will be used to obtain weather data.

We must first configure the project in Android Studio. The following dependencies will be added to the build.gradle file of our new project, which we will create:

These dependencies include the Kotlin Coroutines library, the Retrofit networking library, and the Gson library for parsing JSON data.

Next, we'll create a data class to represent the weather data:

We'll also create a Retrofit service interface to handle the network requests:

Take note that the getCurrentWeather method's usage of the suspend keyword denotes that it is a coroutine function.

We will now design the application's primary action. We'll prepare the user interface (UI) and start a coroutine to handle the network request in the onCreate method:

Kotlin Coroutines Dependencies

The Kotlin language and standard library serve as the foundation for Kotlin coroutines. However, you'll need to add a few more dependencies to your project if you want to use coroutines in an Android application.

The kotlinx-coroutines-core and kotlinx-coroutines-android libraries are the two you'll need to add as dependencies. The launch and async methods for initiating coroutines, as well as the Dispatchers' object for setting the execution context of a coroutine, are provided by these libraries.

An illustration of how to add these dependencies to your build. gradle file is provided below:

Depending on the particular feature you wish to utilize, you might also need to add extra dependencies in addition to these essential ones. For instance, you'll need to add the Retrofit and Retrofit coroutines adapter requirements if you're using coroutines with Retrofit for networking:

Similarly, if you're using coroutines with Room for database access, you'll need to add the Room and Room coroutines dependencies:

Executing in a Background Thread

Understanding how to run code on a background thread is crucial when dealing with Kotlin coroutines. By doing this, you may avoid blocking the main thread, which can make the program unusable and make for a bad user experience.

A method for managing and controlling coroutines inside a certain scope is provided by the CoroutineScope class. Using an existing scope, such as the GlobalScope, or creating a new CoroutineScope using the CoroutineScope() constructor are also options.

Understanding the Usage of CoroutineScope and Dispatcher Classes

Coroutines are assigned to various threads using the Dispatcher class. The Kotlin coroutines library offers several built-in dispatchers:

• Dispatchers.Default:
  For CPU-bound operations without a defined thread need, this dispatcher utilizes a shared pool of threads.
• Dispatchers.IO:
  This dispatcher is designed to handle activities that need I/O, such as network requests and file I/O. Compared to Dispatchers, it employs a bigger thread pool. I/O activities that might be blocked are handled by default.
• Dispatchers.Main:
  This dispatcher is used for running code on the main thread, which is necessary for updating the UI.

How to Run Coroutines on a Background Thread?

The launch function and the Dispatchers object may be used to run a coroutine on a background thread. For illustration, the following is how you could start a coroutine on the IO dispatcher:

This will run the coroutine on a background thread optimized for I/O tasks.

Alternatively, you can use the async function to run a coroutine on a background thread and return a result. Here's an example:

The coroutine will be executed on a background thread and the outcome will be returned to the caller code. The coroutine's completion and return of the result are both awaited using the await() method.

Use Coroutines for Main-Safety

A key idea in Android development is main safety, which makes sure that UI-related operations are carried out on the main thread. This is essential to avoid blocking the UI thread, which might make the program unusable and negatively impact the user experience.

Importance of Main-safety in Android Development

To guarantee that UI-related code is performed on the main thread, Kotlin coroutines offer main safety by default. This implies that any coroutine launched on the main thread will immediately transition to the appropriate dispatcher. The Dispatchers are used for this. Dedicated to executing code on the main thread, the main dispatcher.

Use the proper dispatcher for the job at hand at all times while employing coroutines to guarantee main safety. When initiating a network request, for instance, you should first perform it on a background thread using the Dispatchers.IO dispatcher before switching to the Dispatchers. To update the UI with the outcome, use the main dispatcher.

Handling Exceptions in Kotlin Coroutines

For your app to be responsive and reliable, Kotlin Coroutines must properly handle exceptions. Coroutines offer numerous methods for dealing with exceptions, such as utilizing a try-catch block or the CoroutineExceptionHandler interface to deal with errors on a global scale.

Here's an illustration of how to handle errors in a coroutine using a try-catch block:

This will catch any exceptions that occur within the coroutine and allow you to handle them appropriately.

Alternatively, you can use the CoroutineExceptionHandler interface to handle exceptions globally for all coroutines within a specific scope. Here's an example:

This will deal with any exceptions that arise both within the coroutine itself and in any child coroutines that are launched within the scope.