Creating mobile applications is traditionally associated with the Kotlin or Java languages, but the Python ecosystem offers powerful tools for cross-platform development. If you already know Python syntax, you don't have to learn a new technology stack from scratch to release your product on Google Play. Modern frameworks allow you to transform Python code into a native APK package, ready for installation on any device.
However, this process has its own nuances that differ from classical web development or writing scripts for the server. You will have to deal with the limitations of the mobile operating system, the features of touch controls and the need to optimize the interface for small screens. In this article we will analyze in detail how to make a Python application for Androidusing current tools and avoiding common mistakes of beginners.
Choosing the right framework for mobile development
The first and most critical step is choosing a tool that will be responsible for drawing the interface and interacting with the hardware of the smartphone. The standard Tkinter library, popular among desktop developers, will not work here as it does not support mobile platforms. You need to choose a solution that is specifically adapted to touch screens and the Android architecture.
The most mature and time-tested solution is considered Kivy. This is a framework that uses its own graphics rendering engine via OpenGL ES 2.0. The main advantage of Kivy is its complete independence from native operating system widgets. This ensures that your application will look identical on both Android and iOS or Linux, but requires writing your own CSS-like markup language for the interfaces. An alternative is the project and its library. Unlike Kivy, this approach strives to use each platform's native controls. This means that the button on Android will look like a standard Android button, and on iOS it will look like an iOS button. While this gives a more "native" look to the application, BeeWare's mobile compilation support is still under active development and may be less stable for complex projects. kv for interfaces.
An alternative is the project BeeWare and his library Toga. Unlike Kivy, this approach strives to use each platform's native controls. This means that the button on Android will look like a standard Android button, and on iOS it will look like an iOS button. While this gives a more "native" look to the application, BeeWare's mobile compilation support is still under active development and may be less stable for complex projects.
⚠️ Attention: Don't try to use Flask or Django to create a full-fledged mobile application. These web frameworks are designed for the server side. Although they can be wrapped in a WebView, the performance and user experience will be significantly inferior to native Kivy solutions.
- 🐍 Kivy: Ideal for games, GUIs and applications with a unique design that is not system dependent.
- 🐝 BeeWare (Toga): Suitable for utilities and business applications where compliance is important platform guidelines.
- 📱 Flet: A new player on the market that allows you to create interfaces based on Flutter, but controlled by Python code.
Preparing the environment and installation dependencies
Before writing the first line of code, you need to properly set up your working environment. Android development with Python is rarely done directly on a mobile device; the main process takes place on a PC followed by compilation. For Windows and macOS users, it is critical to have a virtual environment to isolate project packages from system libraries.
Installation of the framework itself is usually done through a package manager pip. However, for Kivy the installation process can be non-trivial due to its dependence on specific SDL2 libraries. On Windows, it is recommended to use pre-compiled wheels or install dependencies pip install kivy.deps.sdl2 kivy.deps.glew before the main installation. Ignoring this procedure often leads to import errors at startup.
To emulate the application on a computer, you will need an Android emulator or connecting a real device via USB. Enable USB debugging mode in the developer options on your smartphone. This will allow you to run debug versions of the code directly on the device, which significantly speeds up the process of testing the interface and operating logic.
python -m venv venv
source venv/bin/activate # For Linux/Mac
venv\Scripts\activate # For Windows
pip install kivy
It is also important to install the utility Buildozerif you are running Linux or macOS. This tool is responsible for packaging your Python script, Python interpreter and all the necessary libraries into a single APK file. On Windows, direct compilation via Buildozer is difficult, so many developers use a virtual machine with Ubuntu or cloud services for building.
Use the `pip freeze > requirements.txt` command immediately after setting up the environment. This will save the exact versions of all libraries, which will save you from compatibility problems when transferring the project to another computer or build server.
Application architecture and interface creation
The structure of a Kivy application differs from conventional scripts. The entry point is a class inherited from Appthat manages the life cycle of the app. Inside the method build you return the root widget, which becomes the basis of the entire user interface. The separation of logic and presentation here is a key principle for code maintainability.
Language is used to describe the interface KV. It is a declarative language that allows you to specify element placement, colors, sizes, and event bindings separately from Python code. A file with the extension .kv is automatically loaded by the framework if its name matches the name of the application class (lowercase without the App suffix). This approach allows designers and developers to work in parallel without conflicting in the same file.
Working with Layouts in Kivy requires an understanding of how elements occupy space. The most often used BoxLayout for linear arrangement (horizontally or vertically) and GridLayout for grid. Correct use of properties size_hint and pos_hint ensures that your application will be displayed correctly on screens with different resolutions and aspect ratios.
| Widget | Purpose | Analog in Android |
|---|---|---|
Button |
Action button | android.widget.Button |
Label |
Text display | android.widget.TextView |
TextInput |
Text input field | android.widget.EditText |
ScrollView |
Scrollable area | android.widget.ScrollView |
Handling events, such as clicks or swipes, is implemented through methods starting with a prefix on_, for example on_press or on_touch_down. You can bind these events both in Python code through the method bind, and directly in the KV file, which makes the code more readable and intuitive.
☑️ Checking the application architecture
Access to device functions and native API
One of the main difficulties when porting Python to mobile platforms is access to hardware. The camera, GPS, accelerometer, vibration motor, and Android file system are protected by a permissions system and are not directly accessible through the standard Python libraries. To solve this problem, a mechanism for wrapping native code is used.
In the Kivy ecosystem, this role is played by the library python-for-android (p4a) and a set of ready-made recipes. Recipes are scripts that automatically download, compile and integrate the necessary native libraries (in Java or C) into your APK. For example, to access the camera, a package is used opencv or specialized wrappers like plyer.
The Library plyer is a universal tool that provides a single API for accessing OS functions on different platforms. You write the code once, and Plyer determines which native implementation to call: on Android it will be Java code, on iOS it will be Objective-C, and on Windows it will be WinAPI. However, it is worth remembering that support for some functions in Plyer may be incomplete or require additional configuration.
⚠️ Attention: Starting with Android 11 (API level 30), the file system access policy has become stricter (Scoped Storage). Your application will not be able to simply read any files on the disk. You must request specific permissions in the manifest and only work in designated directories.
To work with notifications, lights, or sensors, you will have to edit the Buildozer specifications file. In the android.permissions section you need to explicitly list all the rights that the application requires. Lack of the required permission will cause the application to crash when trying to call the corresponding function or to the system silently ignoring the request.
List of critical permissions
camera (Camera), access_FINE_location (Precise GPS), write_external_storage (Write to disk - only for old Android), internet (Network access). Without them, the application will not pass moderation or will not launch.
Compiling and assembling an APK package
The moment of truth for any mobile developer is receiving the installation file. On the Linux platform, this process is most streamlined thanks to the tool Buildozer. It automates the installation of the Android SDK, NDK, Python compilation to bytecode for ARM processors, and packaging it all into an APK. On other OSes you will have to use Docker containers with a buildozer image or virtual machines.
The build configuration is stored in a file buildozer.spec. This file is generated by the command buildozer init and contains dozens of parameters. Here you specify the application name, package name (for example, com.example.myapp), version, screen orientation and, most importantly, a list of requirements. A mistake in the package name can cost you the ability to update the application in the future, since the identifier cannot be changed after publication.
The first compilation process can take a significant amount of time, from 15 minutes to an hour, depending on the power of your computer and Internet speed, since the system needs to download gigabytes of development tools from Google. Subsequent builds will be faster thanks to dependency caching. The result of the work will be a debug APK file that can be installed on your phone for testing.
buildozer -v android debug
To create a signed release version
buildozer -v android release
A simple debug-APK is not enough to publish on the Google Play Store. You need to create a release build signed with a digital key (keystore). This key must be kept secret because losing access to it means you will not be able to release updates to your application. Buildozer allows you to configure automatic signing by specifying the path to the key store and passwords in the specification.
The first APK build is always the longest and most complex. Don't panic if the process freezes during the NDK download phase - this is normal. Use the `-v` flag to display detailed logs to understand at what stage the problem occurred.
Optimizing size and performance
Python applications are traditionally large in size, since the entire language interpreter and standard library are packaged together with the code in the APK. The weight of an empty Kivy application can reach 20-30 MB, which is significantly larger than its Java/Kotlin counterpart. For users with limited bandwidth or memory, this may be a barrier to installation.
To reduce the package size, you can use the flag --include-polyfill or manually exclude unused modules from the standard library in the Buildozer settings. Compressing resources and using bytecode format instead of source files also helps, although this makes debugging more difficult. The latest versions of the tools now support APK separation by processor architecture (arm64-v8a, armeabi-v7a), which also reduces the weight of the distribution. .pyc (bytecode) instead of the original ones .py files, although this makes debugging more difficult. The latest versions of the tools now support APK separation by processor architecture (arm64-v8a, armeabi-v7a), which also reduces the weight of the distribution.
Python's performance on mobile devices is inferior to compiled languages in intensive computing tasks. If your application deals with real-time video processing or complex mathematics, critical sections of the code should be rewritten in Cython or use ready-made native libraries via JNI. Optimizing the rendering cycle and minimizing the number of widgets on the screen also have a positive effect on FPS.
- 🚀 Cython: Allows you to compile critical sections of Python code in C, speeding up work significantly.
- 🗑️ Removal unnecessary libraries: Exclude heavy packages like `numpy` if they are not used directly.
- 📦 Split APKs: Generate separate files for different processor architectures to save space.
⚠️ Attention: Google Play requires new applications and updates to support 64-bit architecture (arm64-v8a). Make sure your
buildozer.specsettingandroid.archsenables this architecture, otherwise the store will reject the download.
Frequently asked questions (FAQ)
Is it possible create a game in Python for Android?
Yes, it is possible and quite popular. The Kivy framework is great for creating 2D games thanks to its multi-touch and accelerometer support. For more complex 3D graphics, you can use Kivy with the engine Panda3D, although setting up such an environment requires high qualifications. However, for highly loaded 3D shooters, it is better to consider specialized engines like Unity or Unreal Engine.
Do you need to know Java to develop in Python for Android?
Deep knowledge of Java is not necessary to create simple and medium-complexity applications. However, a basic understanding of the structure of Android projects and the ability to read error logs (logcat) will be a huge plus. In some cases, when there is no ready-made recipe for the desired function in python-for-android, you may need to write a small wrapper in Java, but this is the exception rather than the rule.
Why does my application crash immediately after launch?
The most common reason is the lack of necessary permissions in the manifest or an error in the initialization code, which is visible only in the logs. Connect your phone to your computer and run the command adb logcat in the terminal when the application starts. Look for lines marked Python or CRITICAL —the exact reason for the failure will be indicated there.
Is it possible to publish an application in the App Store for iOS?
Yes, the Kivy framework supports building for iOS using the tool toolchain and the Xcode environment on macOS. The process is more complicated than for Android and requires a Mac computer, since compiling for iOS is not possible on Windows or Linux. The code logic remains the same, but the build and signature settings are different.
What is the minimum APK size you can get?
With careful optimization, using ProGuard to compress the code and eliminating unnecessary libraries, the minimum APK size for a simple "Hello World" application on Kivy can be increased to 10-15 MB. Without optimization, this figure is usually 25-40 MB. For comparison, a native Java application can weigh less than 1 MB.