How to write an Android application in Python: a complete guide

Mobile development is traditionally associated with the Java and Kotlin languages, but the world does not stand still. More and more developers are looking for a way to use their existing Python skills to create full-fledged mobile applications running Android. This allows you to save time learning new syntax and get your product to market faster.

Although Python is not a native language for the Android platform, there are powerful tools and frameworks that successfully solve this problem. In this article we will analyze in detail how to write an application for Android in Pythonwhich tools to choose for a specific task and what pitfalls you will encounter during the compilation and publishing process.

The issue of performance and the size of the final APK file often becomes a stumbling block. However, modern approaches allow you to create fully working interfaces and backend logic, using the full power of the Python ecosystem. Let's dive into the technical details and look at current implementation methods.

Why Python for mobile applications: pros and realities

Using Python in mobile development has a number of undeniable advantages, especially for startups and projects with a limited budget. The main advantage is the speed of development. Python libraries allow you to implement complex business logic, work with data or neural networks many times faster than in native languages.

In addition, you get access to a huge number of ready-made solutions. If your application requires image analysis, API manipulation, or cryptography, you simply import the module you need instead of writing it from scratch in Java. This makes it an ideal choice for prototyping and MVP. However, be realistic: the interpreted nature of the language does have an impact on performance. For graphics-intensive games or applications that require an instant responsive interface, pure Python may not be suitable. However, for utilities, automation tools and information applications, this is an excellent option. Python ideal choice for prototyping and MVP.

However, it's worth being realistic: the interpreted nature of a language does have an impact on performance. For graphics-intensive games or applications that require an instant responsive interface, pure Python may not be suitable. However, for utilities, automation tools, and information applications, it is a great option.

• 🚀 Cross-platform: one code can run not only on Android, but also on iOS, Windows and Linux.
• 📚 Rich ecosystem: thousands of libraries for any task from parsing to machine learning.
• 💰 Resource saving: No need to hire a separate team of Android developers if you already have Python specialists.

⚠️ Attention: Applications written in Python usually have a larger installation file (APK) size, since a language interpreter and the necessary libraries are supplied with the code. Take this into account when publishing on Google Play.

Choosing a tool: Kivy, BeeWare or Chaquopy?

The first and most important step is choosing a framework. This affects the appearance of your application, the complexity of the build, and the resulting performance. Today there are three main paths, each of which has its own architectural features.

Kivy is the most popular and mature open source framework. It uses its own OpenGL ES 2 rendering engine, which means your app won't look like a standard native Android app. Buttons and menus will be drawn programmatically, which gives complete design freedom, but deprives the usual “native” look.

The second option is BeeWare (in particular, the Toga library). The philosophy of this project is radically different: it strives to use native operating system widgets. This means that on Android your application will look the same as an application written in Java, but the logic will remain in Python.

The third approach is to use a plugin Chaquopy for Android Studio. This method allows you to embed Python code directly into a native Java or Kotlin project. You get access to all the features of the Android SDK while writing complex logic in Python. This is a hybrid approach that professional teams often choose.

Tool	Interface	Difficulty of learning	Best use
Kivy	Custom (OpenGL)	Average	Games, unique design
BeeWare	Native widget	High (beta status)	Business applications, utilities
Chaquopy	Native (Java/Kotlin)	High (requires Android Studio)	Complex projects, AI/ML

Setting up a development environment for Kivy

Let's look at the setup process using the example of the most common framework - Kivy. First, you will need to install Python on your computer. It is recommended to use version 3.8 or higher, since many libraries have not yet been fully adapted to the latest releases.

The next step is to install the framework itself. Open a terminal or command prompt and enter the command to install through the pip package manager. Make sure you have all the required dependencies installed for your operating system (Windows, macOS or Linux).

pip install kivy kivy-deps.angle kivy-deps.glew

After installing the libraries, you need to set up your environment for cross-compilation. Since we're writing code on a PC but running it on Android, we'll need a tool Buildozer. It automatically downloads Google's SDK and NDK, compiles Python code into bytecode, and packages everything into an APK file.

It is important to note that Buildozer works best in a Linux environment. If you are using Windows or macOS, the most reliable way is to use a virtual machine from Ubuntu or a Docker container. This will save you from a lot of problems with paths and dependencies that often arise when installing directly on Windows.

• 🐍 Install the latest stable version of Python from the official website.
• 📦 Use a virtual environment venv to isolate project dependencies.
• 🛠 Install Buildozer command pip install buildozer inside the environment.

⚠️ Attention: For Buildozer to work, the Java Development Kit (JDK) must be installed. JDK version 11 or 17 is the most compatible with current Android SDK versions. Using an outdated JDK 8 may result in compilation errors.

Creating the first interface in the language KV

In the Kivy ecosystem, the interface is separated from the application logic. A special markup language is used to describe the appearance KV. This makes the code cleaner and allows designers or coders to work on the interface independently of the programmer.

Create a file with the extension .kv, the name of which should be the same as the name of your main Python class (without the .py extension). In this file you describe widgets: buttons, labels, input fields. The padding hierarchy in KV files is critical because it defines the nesting of elements.

For example, to create a simple screen with a title and a button, you define a root widget BoxLayoutthat organizes elements vertically or horizontally. Inside it you place Label for text and Button for action. The connection between interface elements and Python functions is carried out through properties on_press or through ObjectProperty.

The logic code is written in a regular Python file. You create a class that inherits from Appand override a method buildthat returns the root widget of your interface. This is where the application is initialized and the main event loop is launched.

Example of KV file structure

root: BoxLayout: orientation:'vertical' Label: text:'Hello, Android!' Button: text:'Click me' on_press: app.say_hello

Building APK and testing on the device

When the code is written and tested on an emulator or PC, the building stage begins. In the project folder, run the command buildozer init. It will create a file buildozer.spec —this is a configuration file where you specify the application name, package name (for example, com.myname.myapp), version and required permissions.

In the specification file, pay attention to the section requirements. Here you need to include python3,kivy any other libraries that you use in the code (for example, requests for working with the network). Buildozer will try to find and compile them for the ARM architecture used in smartphones.

The compilation process is started by the command buildozer -v android debug. The flag -v enables detailed log output, which is extremely useful when searching for errors. The first launch will take a long time, since the system will download the Android SDK, NDK and build tools.

After successful compilation, a file bin . Connect your smartphone via USB, enable “USB Debugging” in the developer menu and install the application with the command .apkwill appear in the folder adb install bin/your_application-debug.apk or simply copy the file to your phone and install manually.

⚠️ Attention: If the build is interrupted with an error related to Android SDK licenses, you need to accept the license agreements through the SDK Manager command line or manually edit the license files in the Android SDK installation directory.

Optimization and publishing on Google Play

The debug version of the application has an increased size and reduced performance, as it contains debugging information. To publish it in the store, you need to build the release version. To do this, Buildozer uses the command buildozer android release.

You will need to create a digital signature key (keystore). This key protects the authorship of your application. Without it, you will not be able to download updates to Google Play Console. Keep the key file and password in a safe place: losing the key means you will not be able to update the application in the future.

Before downloading, be sure to test the application on different versions of Android and screen resolutions. Interfaces built in Kivy can scale differently on tablets and phones with camera cutouts. Use Android Studio emulators to check compatibility.

Be aware of Google Play's metadata policy when publishing. You will need to prepare screenshots, an icon and a description. Although the logic is written in Python, for the user it is a normal application, and it must meet all the quality and safety standards of the store.

• 🔐 Generate a signing key with the command keytool and specify the path to it in buildozer.spec.
• 📉 Use compression tools (เช่น ProGuard or R8) to reduce the size of the final APK.
• 📱 Test operation of the application in the background and when the screen is rotated.

Is it possible to use popular libraries like Pandas or NumPy?

Yes, this is possible, but it requires additional configuration in the file. buildozer.spec. Not all libraries have ready-made compiled versions for ARM. For complex scientific libraries, you sometimes have to use forks or write your own build recipes for Buildozer, which can be a non-trivial task.

Will the application work without the Internet?

Yes, if your application does not request data from the network. Python code runs locally on the user's device. However, if you use third-party APIs or load resources from the cloud, then the connection will be required for the corresponding functions.

Is it difficult to switch from Kivy to native development later?

The transition will require rewriting the interface code from scratch, since Kivy widgets are not compatible with native View Android. However, business logic written in pure Python (mathematics, data processing) can be transferred or integrated through Chaquopy if the project architecture has been partitioned correctly.

What is the minimum version of Android supported?

Usually frameworks like Kivy support starting from Android 4.4 (API 19) or 5.0. However, it is recommended to focus on more recent versions (Android 8.0+), since older versions of the OS have security problems and may not display the modern interface correctly.