Your First Kotlin App: Coding a ‘Hello World’

Nicholas Idoko 17 min read

Last Updated on October 23, 2023

Introduction

Starting with a simple “Hello World” app in Kotlin is crucial as it sets the foundation for learning the language.

This basic app allows beginners to understand the syntax, structure, and workflow of Kotlin programming.

The importance lies in grasping the fundamentals before moving on to more complex applications.

Kotlin’s growing popularity in the programming community makes it even more essential to start with a “Hello World” app.

With its concise syntax and interoperability with Java, Kotlin has gained traction among developers, especially for Android development.

This has led to an increase in learning resources, community support, and job opportunities related to Kotlin.

By starting with a simple app, developers can gradually build their skills and confidence in using Kotlin effectively.

It acts as a stepping stone to explore the language’s features, such as null safety, extension functions, and data classes.

Ultimately, mastering the basics through a “Hello World” app will enable developers to create more sophisticated and robust applications in Kotlin.

So, begin your Kotlin journey with the humble “Hello World” app and unlock the potential of this versatile programming language.

Setting up the Development Environment

In this section, we will walk you through the process of setting up your development environment for creating your first Kotlin app.

Downloading and installing the JDK (Java Development Kit)

Before you start coding in Kotlin, you need to have the JDK (Java Development Kit) installed on your system.

Open your web browser and go to the official Oracle website.

Search for the latest version of JDK and click on the download link.

Choose the appropriate JDK version based on your operating system and click on the download button.

Once the download is complete, run the installer and follow the on-screen instructions to install the JDK.

After the installation is complete, open your command prompt (or terminal) and type “java -version” to verify the installation.

Installing Android Studio with Kotlin support

Android Studio is the official IDE (Integrated Development Environment) for Android app development, and it provides built-in support for Kotlin.

Follow these instructions to install Android Studio on your system.

Open your web browser and go to the official Android Studio website.
Click on the “Download” button and wait for the download to complete.
Run the downloaded installer and follow the on-screen instructions to install Android Studio.
Make sure to check the box for installing the Kotlin plugin during the installation process.
Once the installation is complete, launch Android Studio and select “Start a new Android Studio project”.
Choose a project template and click on the “Next” button.
Set the project name and minimum SDK version, and select the language as “Kotlin”.
Click on the “Finish” button to create the project.

Congratulations! You have successfully set up your development environment for coding in Kotlin.

In the next section, we will guide you through the process of coding your first ‘Hello World’ app in Kotlin. Stay tuned!

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Creating a New Project in Android Studio

Creating a new project in Android Studio is the second step in coding our first Kotlin app.

To accomplish this, follow these steps:

Open Android Studio and select “Start a new Android Studio project” from the home screen.
A dialog box will appear, prompting you to choose a template for your app. Select the one that suits your needs.
After selecting the template, you will be asked to configure the project settings. This includes providing a name for your app, choosing a package name, and selecting the minimum SDK version.
Next, select the language you want to use for coding your app. In this case, choose Kotlin.
Android Studio will now start creating your new project based on the template and settings you provided.
Once the project is created, you will see the project structure on the left-hand side of the Android Studio window.
The initial files and folders of your project will be displayed here. These include the app folder, which contains all the code and resources for your app.

Now, it’s time to explore the various components of your project. Take a moment to familiarize yourself with the different directories and files.

The “app” folder is where most of your work will take place. Inside this folder, you will find subdirectories for activities, layouts, and other resources.

The “MainActivity.kt” file is the starting point of your app. It contains the code for the main activity, which is the entry point of your app.

By default, Android Studio creates a basic “Hello World” app with a single activity. You can modify this code to customize your app further.

Choose a template and configure the project settings as needed

Now that your project is set up, you can start coding your app by adding functionality and designing user interfaces.

Android Studio provides a visual editor, layout files, and a code editor for Kotlin, making it easy to build your app.

As you code your app, make sure to test it frequently on different devices and screen sizes using the built-in emulator or a physical device.

Don’t forget to regularly save your project and commit it to a version control system like Git to track changes and collaborate with others.

Android Studio also provides various debugging tools that can help you identify and fix any issues in your app.

Remember to write clean and maintainable code, follow best practices, and document your code for future reference.

Finally, once you are satisfied with your app, you can build a release version of it and distribute it to users through the Google Play Store or other app stores.

Creating a new project in Android Studio is the crucial step in kickstarting your Kotlin app development journey.

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Your First Kotlin App: Coding a 'Hello World'

Adding Kotlin Support

Enable Kotlin support in the project by selecting “Include Kotlin support.”

Kotlin offers several benefits for Android app development that make it worth considering.

Kotlin is a modern programming language that is fully interoperable with Java.

It is concise, expressive, and reduces boilerplate code, making development faster and more efficient.

Kotlin has null safety built into its type system, reducing the chances of null pointer exceptions.

It provides powerful features like extension functions, smart casts, and data classes, enhancing developer productivity.

Kotlin is fully supported by Google, making it a recommended choice for Android development.

It offers seamless integration with existing Java code, allowing gradual adoption in existing projects.

Kotlin has excellent tooling support, with features like auto-completion and error checking in popular IDEs like Android Studio.

It has a large and active community contributing libraries and resources to aid development.

Kotlin supports functional programming paradigms, allowing developers to write more concise and readable code.

It provides coroutines for asynchronous programming, simplifying tasks like network requests and database operations.

Benefits of using Kotlin for Android app development

Kotlin supports Android-specific annotations and features, like the @Parcelize annotation for Parcelable objects.

It offers improved nullability handling, reducing the occurrence of NullPointerExceptions in Android apps.

Kotlin is fully compatible with Java libraries, allowing developers to leverage existing code and libraries.

It offers easy integration with popular frameworks like Dagger for dependency injection and Retrofit for networking.

Kotlin has excellent documentation and learning resources, making it easy for developers to get started.

It has a high adoption rate among top companies in the Android ecosystem, ensuring its long-term viability.

Kotlin’s concise syntax and modern features make code more readable and maintainable, reducing developer frustration.

It provides advanced language features like sealed classes, inline functions, and type aliases, increasing code expressiveness.

Kotlin enables developers to write safer code by leveraging features like non-nullable types and strict data classes.

It supports functional programming patterns like immutability and pure functions, leading to more reliable code and fewer bugs.

Kotlin’s strong type inference enables developers to write code without explicitly specifying types, reducing verbosity.

It offers simplified syntax for common Android tasks like handling shared preferences, RecyclerViews, and SQLite databases.

Kotlin’s seamless integration with Java allows developers to adopt it gradually in existing projects without rewriting the entire codebase.

Overall, Kotlin is a powerful and modern language that offers numerous benefits for Android app development.

By adding Kotlin support to your project, you unlock a wide range of modern features, improved productivity, and a more enjoyable development experience.

Whether you are starting a new project or migrating an existing one, Kotlin is definitely worth considering.

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Coding the “Hello World” App

To start coding the “Hello World” app in Kotlin, you need to create a new Kotlin file for the main activity.

This can be done by right-clicking on the package where you want the file to be created, and selecting “New -> Kotlin Class.”

Once you’ve selected “Kotlin Class,” you’ll be prompted to name the file.

Choose a name that makes sense for your app. For example, if your app is called “HelloApp,” you might name the file “MainActivity.”

After naming the file, you’ll be asked to choose the superclass for your main activity.

In this case, select “Activity” as the superclass.

This will allow you to extend the functionality of the Android Activity class.

Now that you’ve created the Kotlin file for your main activity, it’s time to implement the necessary code to display “Hello World” on the screen.

To do this, you’ll need to override the onCreate() function in your MainActivity class.

Inside the onCreate() function, you’ll use the setContentView() method to set the layout for your activity.

This method takes a layout resource id as its parameter.

In this case, you’ll use the built-in layout resource file called “activity_main.xml,” which comes with a TextView already defined.

To display “Hello World” on the screen, you’ll need to find the TextView view in your layout and set its text property to “Hello World.”

This can be done using the findViewById() method, which takes the ID of the view as its parameter.

Once you have a reference to the TextView view, you can call its setText() method and pass “Hello World” as the parameter.

This will update the text displayed by the TextView.

Implement the necessary code to display “Hello World” on the screen

Finally, to see the “Hello World” message on the screen, you’ll need to run your app on an emulator or a physical device.

Android Studio provides a built-in emulator that you can use for testing.

Congratulations! You have successfully coded a “Hello World” app in Kotlin.

This simple app is often the first step in learning any programming language or framework. It’s a great way to get started and familiarize yourself with the basics of app development.

In the next section, we will explore more advanced topics and build upon the foundation laid in this section. Stay tuned for more exciting coding examples and explanations.

Building and Running the App

Once you have finished coding your Hello World app in Kotlin, the next step is to build and run the project. Follow these steps to successfully build and run your app:

1. Building the project

Open Android Studio and make sure your project is open.
In the top menu, click on “Build” and then select “Make Project” from the options.
Android Studio will now start building your project, which may take a few moments.
Once the build is complete, you will see a message indicating the build status.

2. Running the app on an Android emulator or device

To run the app on an Android emulator, make sure you have set up an emulator beforehand.
In the top menu, click on “Run” and then select “Run ‘app'” from the options.
Android Studio will display a list of available emulators for you to choose from.
Select the desired emulator and click on the “OK” button to start running the app.
The emulator will now launch, and you will see your Hello World app running on the emulator screen.

Alternatively, you can also run the app on a physical Android device by following these steps:

Connect your device to your computer via USB.
On your Android device, go to “Settings” and enable “Developer options” by tapping on the “Build number” multiple times.
Once enabled, go to “Developer options” and enable “USB debugging”.
In Android Studio, click on “Run” and then select “Run ‘app'” from the options.
A dialog box will appear, displaying the list of connected devices.
Select your device from the list and click on the “OK” button to start running the app.
The app will be installed and launched on your connected Android device.

Congratulations! You have successfully built and run your Kotlin Hello World app.

Now you can see the “Hello World” message displayed on the emulator or device screen.

This is just the beginning of your journey into Kotlin app development, and there is a lot more to explore and learn.

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Conclusion

Coding a “Hello World” app in Kotlin involves a few simple steps.

Firstly, make sure you have the necessary tools like Android Studio and the Kotlin plugin.

Then, create a new project and choose Kotlin as the programming language.

Next, open the MainActivity file and write the code for the “Hello World” app, which consists of just a single line. After that, run the app on an emulator or a physical device to see the message displayed on the screen.

Overall, Kotlin offers simplicity and efficiency in Android development.

Its concise syntax allows for faster and more intuitive coding.

Developers can leverage Kotlin’s powerful features, such as null safety, extension functions, and lambda expressions, to build robust and performant applications.

To further explore Kotlin’s capabilities, developers can take advantage of the vast resources offered by the Kotlin community.

There are numerous tutorials, documentation, and forums available to help developers enhance their Kotlin skills and tackle more complex app development challenges.

Additionally, Kotlin’s seamless interoperability with Java makes it easier to migrate existing Java projects to Kotlin and enjoy its benefits.

In summary, developing a “Hello World” app in Kotlin is a great starting point for learning and experiencing the simplicity and efficiency of this programming language in Android development.

By delving deeper into Kotlin’s features and community resources, developers can unlock endless possibilities for creating innovative and cutting-edge applications.