Mobile application development today is one of the most popular and highly paid areas in the IT industry. Billions of devices around the world run on the operating system Google Android, and the demand for high-quality software is only growing. If you are wondering how to learn how to write apps for Android, then you are on the verge of an exciting journey into the world of code, logic and the creation of digital products.
Everyone can start this path, regardless of age or previous experience, but it is important to immediately get ready for serious work. You will have to master not only the syntax of the programming language, but also understand the architecture of mobile devices, principles of working with memory and features of the user interface. The modern market dictates high quality standards, therefore fundamental knowledge here it is more important than the ability to quickly copy someone else's code.
In this article we will analyze all stages of training: from choosing tools to publishing the first application. We will not use complex terminology without explanation, but will focus on practical steps that will allow you to create a working project in the first weeks of training. The willingness to learn and experiment is the main key to success in this profession.
Choosing a programming language and development environment
The first and most critical step is choosing the tool on which you will write code. For a long time, language was considered the de facto standard Java, in which most legacy code in existing applications is written. However, in 2017, Google officially announced Kotlin the preferred language for Android development. It is more concise, safer, and frees the developer from many of the routine errors inherent in older approaches.
To write code, you will need an integrated development environment (IDE). The undisputed leader here is Android Studio, based on the platform IntelliJ IDEA. It is a powerful tool that provides everything you need: a code editor, a device emulator, a debugger, and profiling tools. There are alternatives, such as Visual Studio Code or Eclipse, but for a beginner they can create more problems than they solve due to the complexity of setting up the environment.
Start learning right away with Kotlin. This will save you time in the future, as new libraries and documentation focus on this language first.
Installing software requires care. It is important to download distributions only from official developer sites to avoid malicious modifications. The installation process Android Studio can take considerable time, since the system will need to load additional components, including a compiler and system images.
- 🚀 Kotlin - a modern, concise and safe language recommended by Google.
- ☕ Java - a classic language with a huge knowledge base and libraries.
- 🛠️ Android Studio - official IDE with all necessary tools.
- 📦 SDK Manager —a component for loading Android versions and platform tools.
⚠️ Attention: Do not try to write code for mobile applications in simple text editors without plugin support. The absence of code completion and code linter will lead to many errors that will be extremely difficult for a beginner to debug.
Installing and configuring Android Studio
The process of setting up a working environment is the stage where many beginners encounter the first difficulties. After downloading the installer Android Studio from the developer's website, run it and follow the instructions of the installation wizard. The system will prompt you to select components that will be installed with the IDE. Among them must be Android SDK (Software Development Kit) - a set of tools without which the creation of applications is impossible.
Pay special attention to the choice of installation location. The folder path should not contain Cyrillic characters or spaces, as some build tools may not work correctly. After installation is complete, launch the app. When you launch it for the first time, a window will open Welcome to Android Studiowhere you need to select the item Standard to set the recommended settings.
File -> Settings -> Appearance & Behavior -> System Settings -> Android SDKInside the SDK settings menu you will see a list of available versions of the operating system. To get started, just select the latest stable version, for example Android 14 (API 34) or the one marked as Recommended. Also make sure that in the SDK Tools section Android SDK Build-Tools and Android Emulatorare installed. Without an emulator, you will have to constantly connect a physical device for testing, which is not always convenient.
☑️ Checking the environment
Emulator configuration is the creation of a virtual phone on your computer. In the window Device Manager click Create Device, select the model (for example, Pixel 6) and the system image. After creating the device, you can launch it directly in the app window, simulating the operation of a real smartphone. This allows you to test applications even without having a physical gadget at hand.
Structure of the first project and IDE interface
When the environment is ready, let's create the first project. Click New Project and select a template Empty Activity. This is a basic template that contains the minimum code required to run the application. In the window that opens, enter the name of the project (for example, MyFirstApp), specify the package (package name), which must be unique (usually in the format com.example.myapp), and select the language. Kotlin.
Interface Android Studio may seem overloaded, but it is logical. On the left is the project panel (Project), where the file structure is displayed. The central part is the code editor. On the right are tools for working with layouts and element properties. At the bottom there is an output panel (Build, Logcat), where error messages and compilation results are displayed.
What is Gradle?
Gradle is a build automation system. It manages dependencies (libraries), compiles the code and packages it into an APK file. When you first start a project, Gradle may take a long time to download files from the Internet - this is normal behavior, you just need to wait until the process is completed.
Key project files that you will work with constantly:
- 📄
AndroidManifest.xml— application passport, which describes access rights and components. - 🎨
activity_main.xml— interface markup file (UI), where buttons and text. - 💻
MainActivity.kt—a file with operating logic written in Kotlin. - 📦
build.gradle—a configuration file where external libraries are connected.
It is important to understand the difference between resources and code. All images, lines of text and styles are stored in the folder res. Using resources allows you to easily adapt the application to different languages and screens without rewriting the main code. For example, it is better to store the text of a button in a file strings.xmlrather than hard-code it in code.
Basics of interface markup (XML) and logic (Kotlin)
Creating an application for Android is divided into two parts: visual (how it looks) and logical (how it works). The visual part is described in XML (Extensible Markup Language). In the file activity_main.xml you place interface elements called Views. The most popular of them: TextView (text), Button (button), EditText (input field) and ImageView (image).
Each element has attributes that determine its appearance and behavior. For example, the android:text attribute specifies the text, and android:layout_width the width. To arrange elements, Layouts (layouts) are used, such as ConstraintLayout, LinearLayout or FrameLayout. They determine how elements will behave on screens of different sizes.
<Buttonandroid:id="@+id/myButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Click me" />
The application logic is written in a file MainActivity.kt. Here you find interface elements by their ID and assign actions to them. For example, you can make the text on the screen change when you click a button. To do this, use the function setOnClickListener.
The connection between XML and Kotlin is carried out through a unique identifier (ID). Without an assigned ID in the XML file, you will not be able to control the element from code.
⚠️ Attention: Interfaces and names of tools in Android Studio may be updated with the release of new versions. If you don't find the menu, use the settings search (Ctrl+Shift+A) or check the official documentation, as the location of the items may change.
Comparison of development approaches: Native vs Cross-platform
Before diving in, it's worth considering alternatives to native development. Native development involves creating applications specifically for one platform (Android or iOS) using native languages (Kotlin/Java or Swift). This gives maximum performance and full access to all device functions, but requires writing separate code for each system.
Cross-platform development allows you to write code once and run it on both platforms. Popular frameworks: Flutter (Dart language), React Native (JavaScript) and Kotlin Multiplatform. They use special bridges to interact with native components. The choice of approach depends on the goals of the project: for complex graphic games or AR applications, native is better, and for business applications and services, a cross-platform.
| Criterion | Native (Kotlin) | Cross-platform (Flutter/React Native) | Web App (PWA) |
|---|---|---|---|
| Performance | Maximum | High | Medium |
| Access to device API | Full | Via plugins | Limited |
| Development speed | Longer (2 code bases) | Faster (1 base) | Very fast |
| Application size | Minimal | More (engine) | Depends on cache |
For a deep understanding of how Android apps work, it is still recommended to start with native development in Kotlin. This will give you an understanding of the fundamental principles of the operating system, application lifecycle, and memory management. Switching to cross-platform tools later will be much easier with this background.
Debugging, testing and publishing
Writing code is only half the battle. The second, no less important part is finding and correcting errors. In Android Studio a tool Logcatis used for this. It displays all system messages and errors of your application in real time. If a app crashes or behaves strangely, the first thing you need to do is look in Logcat, look for red lines (Exceptions) and analyze the call stack.
Testing should be carried out on different devices and versions of Android. What works on an emulator with the latest Android may break on a real phone from three years ago. Use Android Virtual Device (AVD) manager to create emulators with different screen characteristics and OS versions. It is also useful to connect your physical smartphone in USB debugging mode.
When the application is ready, the publishing stage begins. To place the app in the store Google Play you need to create a developer account (one-time fee $25). Before downloading an APK file (or Android App Bundle), you need to prepare a description, screenshots, icon, and follow security policies. The moderation process can take from several hours to several days.
- 🐞 Debug — debugging mode, which allows you to execute the code step by step.
- 📱 Emulator —virtual device for testing.
- 📝 Logcat —log of system events and errors.
- 🚀 Release —final assembly for publication in store.
How to fix the "App keeps stopping" error?
This error most often occurs due to a NullPointerException (an attempt to access a non-existent object) or a lack of permission in the Manifest. Check Logcat, find the first red line with the name of your package, and read the reason for the exception (Caused by..). Often the problem is solved by checking the initialization of variables or adding the missing permission.
Do you need to know mathematics to app on Android?
For most standard applications (news, social networks, business services), higher mathematics is not required. Basic logic and the ability to build algorithms are enough. However, if you plan to develop games, AR applications or complex graphics editors, knowledge of linear algebra and geometry will be extremely useful.
How long does it take to learn how to write simple applications?
With regular training (2-3 hours a day), basic skills for creating a simple application (calculator, task list, weather widget) can be mastered in 1-2 months. To obtain the profession of a Junior developer, it usually takes from 6 to 12 months of intensive practice and study of additional technologies (databases, networks, architecture).