Development of Android applications: from idea to publication on Google Play

Creating mobile applications for Android is one of the most in-demand skills in the IT field. According to data Statistain 2026, the share Android of the mobile OS market exceeds 70%, and the number of applications in Google Play exceeded 3.5 million. But how do you start developing your own app if you've never written code? This article will help you understand the basics: from choosing tools to publishing the finished product.

We will not delve into programming theory - instead, we will focus on practical steps. You will learn which programming language is best to choose to start with (Kotlin or Java), how to set up the development environment Android Studio, and what mistakes beginners most often make. And if you have already tried to write code, but encountered difficulties, here you will find solutions to typical problems.

Important: development for Android requires not only knowledge of the syntax, but also an understanding of the architecture of mobile applications. We will look at how activities, fragments and serviceswork, and also show how to test the application on real devices and emulators. Ready to get started?

1. Choosing a programming language: Kotlin vs Java

The first question any beginner asks: what language should I write in? Until 2019, Java was the only official language for Android, but today Google recommends Kotlin as a priority. Why?

Kotlin is a modern language with a concise syntax that solves many problems Java (for example, NullPointerException). It is fully compatible with Javabut requires less code to implement the same functionality. For example, creating a data class in Kotlin takes one line, while in Java you will need 10–15 lines of boilerplate code.

• ✅ Kotlin is the official recommendation Google, less code, better readability
• ⚠️ Java - more vacancies for legacy projects, but more difficult to learn
• 📱 C++/C# - for game engines (Unity, Unreal Engine)
• 🌐 Dart (Flutter) - cross-platform development (not native Android)

If you are just starting out, choose Kotlin. It is easier to learn, and most modern tutorials and documentation Android are focused on it. However, if you need to support old projects or work in a company with legacy code, you will have to learn Java.

⚠️ Attention: In 2026 Google announced a gradual withdrawal of support Java 8 in new versions Android Studio. If you choose Java, make sure that your project is compatible with Java 11+.

2. Setting up the development environment: Android Studio

Android Studio — official IDE (integrated development environment) from Google, which includes all the necessary tools: code editor, device emulator, debugger and build system Gradle. You can download it for free from the official website.

After installation, follow these steps:

1. Run Android Studio and wait for the initial setup to complete.
2. In the menu Configure → SDK Manager install the latest version Android SDK (for example, Android 14 (API 34)).
3. Create a new project via File → New → New Projectby selecting the template Empty Activity.
4. Wait for the dependencies to sync (this may take a few minutes). Gradle synchronizes dependencies (this may take several minutes).

Please note on the project structure:

• app/src/main/java/ — the source code is stored here Kotlin/Java.
• app/src/main/res/ — resources (layouts, images, lines).
• app/build.gradle — build configuration (SDK version, dependencies).

If you have a weak computer, the emulator may slow down. In this case, use a physical device for debugging. To do this:

1. Enable Developer mode on your phone (click on the build number in Settings → About phone).
2. Activate USB debugging in the developer settings.
3. Connect phone to the PC and confirm trust in the device.

3. Basics of Android application architecture

To write a working application, it is not enough to know the syntax of the language - you need to understand how the platform works Android. Main components:

Component	Description	Usage example
Activity	One screen with user interface	Login screen, main menu
Fragment	Part of the interface that can be reused	Tabs in the application, dialog boxes
Service	Background process without UI	Playing music, downloading files
Broadcast Receiver	System event handler	Low battery alerts
Content Provider	Data access control	Sharing contacts between applications

For example, when you open an application, main Activityis launched. If you go to another screen, a new one is created Activity or replaced Fragment. Services work in the background - for example, when you listen to music in Spotify, even minimizing the application.

Special messages are used for communication between components. For example, to open a web page, you send Intent - special messages. For example, to open a web page you send an explicit Intent:

val intent = Intent(Intent.ACTION_VIEW, Uri.parse("https://example.com"))
startActivity(intent)

⚠️ Attention: Starting with Android 12 (API 31), to work with Intent in some cases, an explicit indication of the package is required (setPackage()), otherwise the system may block the transition.

What is AndroidManifest.xml?

This is a configuration file where all application components (Activity, Service, etc.), permissions (for example, Internet access) and metadata are declared. Without the correct settings in this file, the application will not start.

4. User interface development: XML vs Jetpack Compose

Interface Android can be created in two ways:

1. XML layouts —the classic approach with markup in files .xml (for example, activity_main.xml).
2. Jetpack Compose —a modern framework for declarative description of the UI directly in Kotlincode.

Example of a button in XML:

<Button
android:id="@+id/myButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Press me" />

The same element on Jetpack Compose:

Button(onClick = { / action / }) {
Text("Click me")
}

Since 2023, Google recommends using Jetpack Compose for new projects, as it simplifies the development of adaptive interfaces and reduces the number of boilerplate code. However XML is still relevant for supporting old projects.

• 📄 XML — time-tested, many tutorials, but it is difficult to support large layouts
• ✨ Jetpack Compose — modern, flexible, but requires learning new syntax
• 🔄 Hybrid approach — you can combine both methods in one project

5. Testing and debugging the application

Even a simple application needs to be tested before release. Android Studio there are built-in tools for this:

• 🐞 Logcat — log output for finding errors (available in the bottom panel of the IDE).
• 📱 Android emulator — a virtual device for testing on different versions of the OS.
• 🔍 Android Profiler — analysis of CPU, memory and network usage.
• 🧪 JUnit/Espresso —automated testing of UI and business logic.

To run the application on the emulator:

1. Create a virtual device via Tools → Device Manager.
2. Select configuration (for example, Pixel 6 c Android 14).
3. Click Run (green triangle) in Android Studio.

If the application crashes, look for errors in Logcat. For example, NullPointerException means that you are trying to use an uninitialized object. A common mistake for beginners is to forget to declare Activity v AndroidManifest.xml:

<activity android:name=".MainActivity" />

⚠️ Attention: When testing on a real device, disable battery optimization for Android Studio (Settings → Applications → Android Studio → Battery → Unlimited), otherwise debugging may be interrupted.

6. Publish to Google Play: step by step

When the application is ready, you can publish it to Google Play. To do this:

1. Create a developer account in Google Play Console (one-time payment $25).
2. Prepare signed APK/AAB (use Build → Generate Signed Bundle / APK in Android Studio).
3. Fill in information about the application: name, description, screenshots (minimum 2), icon (512×512 pixels).
4. Indicate the category, age rating and privacy policy (required!).
5. Download the assembly and submit for review (usually takes 1-3 days).

Important requirements Google Play in 2026:

• 📦 Mandatory format Android App Bundle (AAB) instead of APK.
• 🔒 Applications for children must comply COPPA (Children's Internet Protection Act).
• 📱 Support Android 12+ (API 31+) for new applications.
• 🛡️ Mandatory privacy policy (even if the application does not collect data).

After publication, follow user reviews and metrics in Google Play Console. If the application crashes on certain devices, use Android Vitals to diagnose problems.

⚠️ Attention: Rules Google Play are updated regularly. Before publishing, check the latest requirements in Play Consoleespecially if your application uses permissions (for example, access to contacts or location).

7. Typical mistakes of beginning developers

Even experienced programmers sometimes make mistakes, and beginners even more so. Here are the most common:

• 🚫 Ignoring the Activity life cycle → memory leaks, crashes when the screen is rotated.
• 🔄 Storing data in static variables → the application can be killed by the system at any time.
• 📡 Working with the network in the main thread → NetworkOnMainThreadException (starting from Android 3.0).
• 🔑 Hard coding of API keys → risk of leakage (use androidx.security:security-crypto).
• 📱 Testing on only one device → compatibility issues on other screens/versions.

An example of correct processing of network requests (using Coroutines):

viewModelScope.launch(Dispatchers.IO) {
try {
val response = api.fetchData() // network request
withContext(Dispatchers.Main) {
updateUI(response) // updating the UI in the main stream
}
} catch (e: Exception) {
Log.e("NetworkError", e.message ?: "Unknown error")
}
}

Another common problem is leaks. memory. They occur when objects are held in memory unnecessarily (for example, through static links to ActivityTo find leaks, use Android Profiler or library LeakCanary.

How to check for memory leaks?

Install the LeakCanary library, launch the application and interact with it. If there is a leak, a message will appear in the logs with a stack trace showing which object is holding the reference.

FAQ: Answers to frequently asked questions

How long does it take to learn how to develop Android applications?

If you have never programmed, it will take you to master the basics Kotlin and basic architecture Android will go away 3–6 months with regular classes (2-3 hours a day). To create a simple application (for example, a task list), a month is enough. For complex projects (social networks, games) it may take a year or more.

Is it possible to develop Android applications on Mac or Linux?

Yes, Android Studio supports Windows, macOS i Linux. The only difference is that additional settings may be required Linux additional configuration may be required KVM to speed up the emulator. Also make sure that you have enough RAM (minimum 8 GB for comfortable work).

Do you need to pay for publishing on Google Play?

Yes, registering a developer account costs $25 (one-time). Downloading applications and updates is free, but Google takes 30% commissions on sales and subscriptions (for the first $1 million of revenue per year, the commission is reduced to 15%).

How to make money on an Android application?

There are several monetization models:

• 💰 Paid application —users buy it in Google Play.
• 📺 Advertising —integration AdMob or other networks.
• 🔑 Subscriptions/Freemium —basic version is free, advanced features paid.
• 🛒 In-app purchases — sale of virtual goods (for example, in games).

The most popular model is free application with advertising + optional paid version without unnecessary water.

What books/courses do you recommend for studying?

For beginners:

• 📖 Book: "Android Programming: The Big Nerd Ranch Guide" (Kotlin version).
• 🎓 Course: "Android Basics in Kotlin" from Google (free on developer.android.com).
• 🎥 YouTube: channel "Android Developers" (official tutorials from Google).

For advanced: study Clean Architecture, Jetpack Compose i Kotlin Coroutines.