How to create an application in Python for Android

Mobile application development is traditionally associated with the Java and Kotlin languages for the platform Android. However, thousands of developers around the world are wondering: is it possible to use your favorite Python to create native or cross-platform solutions? The answer is clear: yes, it is possible, and the tools for this are becoming more powerful every year.

Using Python allows you to significantly reduce development time thanks to its concise syntax and a huge ecosystem of libraries. You don't need to be a Java expert to get your product on Google Play. In this article, we will look at the main approaches, tools and pitfalls that you will encounter when creating a mobile application in Python.

It is worth noting right away that the path from a script on a computer to an apk file on a smartphone is not always direct. There are various frameworks, each of which has its own compilation features and restrictions on access to hardware devices. Let's take a closer look at what tools will help you realize your plans.

Choosing a suitable framework for development

The first and most critical step is to choose a tool that will convert your Python code into an Android-readable format. Today, several solutions are in the lead, each of which is suitable for different types of tasks. Kivy remains the most popular choice for creating applications with its own graphical interface that does not depend on system widgets.

If your task requires strict adherence to material design Google and the use of native controls, it is worth taking a closer look at Buildozer in conjunction with Kivy or framework BeeWare. The latter attempts to use each platform's native widgets, which makes the application more "native" to the user, but can complicate the development of complex interface logic.

For applications focused on data or rapid prototyping, SL4A (Scripting Layer for Android) is sometimes used, although this project is currently supported by the community and has limitations. The choice depends on how deeply you plan to integrate with the Android system.

• 🚀 Kivy —an ideal choice for games and custom interfaces with multi-touch support.
• 🎨 BeeWare —suitable for those who value native controls and a strict style of the platform.
• ⚙️ Buildozer —an automation tool that simplifies building a project for Android.
• 📱 SL4A —a solution for simple scripts and automation of tasks on the device.

⚠️ Attention: The Kivy framework uses its own rendering engine, so your application may look different than standard Android apps. This needs to be taken into account when designing the UX.

Setting up the environment and installing dependencies

Before writing the first line of code, you need to prepare the working environment. Development for Android in Python requires not only the interpreter itself, but also a set of tools for cross-compilation. You will need to install Python version 3.8 or higher, as well as version control system Git.

The key component for assembly is Buildozer. This tool automatically downloads the required dependencies, including Android SDK, NDK and Apache Ant. Installation is done through the package manager pip. After installation, you need to initialize the project in an empty folder by executing the command in the terminal.

pip install buildozer
buildozer init

After executing the command buildozer init a file will appear in the project directory buildozer.spec. This is a configuration file where you specify the application name, package ID, required permissions and library versions. Proper configuration of this file is the key to successful compilation.

Please note that the first build process may take considerable time, since the system needs to download several gigabytes of development tools from Google. Make sure that you have a stable Internet connection and enough disk space.

Creating an interface using KV Language

B ecosystem Kivy a special markup language is used to describe the interface - KV Language. It allows you to separate the application logic (written in Python) from the visual part. This makes the code cleaner and more maintainable, especially when the interface becomes complex.

Files with the extension .kv describe widgets, their properties and location on the screen. You can create buttons, labels, input fields and complex layouts using nesting and rules. The KV syntax is intuitive and reminiscent of CSS combined with a tree structure.

Let's look at a simple example of creating a button and a label. In the Python file you define the application class, and in the KV file you describe what it should look like. The connection between them is carried out through the class name. For example, if your class is called MainApp, then the corresponding block in the KV file will be called MainApp:.

Component	Description	Usage example
BoxLayout	Container for linear arrangement	Placing buttons in a row
Label	Text label	Display title
Button	Interactive button	Start action on click
TextInput	Text input field	Registration form
Image	Display graphics	Application logo

Use KV Language also allows you to easily implement dynamic changes. You can bind widget properties to variables in Python code, creating a reactive interface. This is especially useful for applications where data is frequently updated.

Application logic and working with events

The main power Python is revealed in the business logic of the application. You can use all standard language libraries, as well as third-party packages for working with networking, databases, and computing. However, it is worth remembering the limitations of the mobile environment.

Event processing in Kivy occurs through class methods. For example, to respond to a button click, you define a method in a Python class and bind it to an event on_press in the KV file. This allows for a clear separation of responsibility between the interface and the code.

When working with long-running operations, such as server requests or complex calculations, it is critical not to block the main interface thread. Otherwise, the application will freeze and the Android system will prompt the user to close it. To solve this problem, use a module threading or asynchronous mechanisms provided by the framework.

Why does the application freeze?

If you perform a heavy operation (for example, downloading a large file) on the main thread, the interface stops updating. Android considers an application not responding (ANR) if it does not respond to input for more than 5 seconds. Always move such tasks into separate threads.

Access to device functions, such as camera, GPS or accelerometer, is carried out through special wrapper libraries, for example plyer. This library provides a single API for accessing hardware capabilities on different platforms, abstracting the developer from the specifics of Android.

Building the project and obtaining the APK file

When the code is written and tested on an emulator or a real device in debug mode, the moment of truth comes - building the release version. This is where Buildozercomes into play. The build command is simple, but it hides the complex process of compiling Python code into bytecode and packaging all resources.

To start the build, use the command buildozer android debug for a debug version or buildozer android release for publication. The process may take from 10 to 30 minutes depending on the power of your computer. During the build, temporary files are created that can be deleted after successful completion.

The finished file .apk will appear in the folder bin inside the project directory. This file can already be installed on your smartphone. However, to publish to the Google Play Store, you will need to sign the app with a digital key. Buildozer can help you create a key, but it’s better to do it consciously and save the key file in a safe place.

• 🔑 Keystore — a file with a digital key, without which you will not be able to update your application in the store.
• 📦 APK — Android installation package, the result of the compiler.
• 🛠️ AAB — a new publication format (Android App Bundle), which also is supported by modern versions of the tools.

⚠️ Attention: Never lose the keystore file. If you lose it, you will not be able to release an update for your application on Google Play and will have to create a new application with a new package name.

Optimizing size and performance

One ​​of the main problems of Python applications is their size. Since the entire Python interpreter and necessary libraries are packaged with your code, even a simple "Hello World" can be over 20-30 MB. This may discourage users with limited bandwidth or memory.

To reduce the size of the APK, it is recommended to use the tool PyInstaller (in the context of a desktop) or specific optimization flags in Buildozer. It is also worth removing unused modules from the standard library in the configuration file. The less code you include, the lighter the app will be.

Python performance on mobile devices is lower than native C++ or Kotlin code. It is better to rewrite critical sections of code that require high computation speed in Cython or put them into separate modules in C. This will speed up the application significantly.

Using Cython to compile critical sections of code can speed up the execution of mathematical operations by up to 100 times compared to pure Python.

It is also important to optimize the use graphics. Loading large images into memory without compression may cause the application to crash due to insufficient RAM (OOM Error). Use compressed texture formats and load resources as needed.

Publishing in the Google Play Store

The final stage is uploading the application to the store. Google Play requires strict design and security guidelines. You need to create a developer account, fill out a description, upload screenshots and the file itself .aab or .apk. Before publication, the application is moderated.

Make sure that your application only requests the permissions that it actually needs to function. Excessive permission requests (such as flashlight contact access) are a common reason for app rejection by moderators. The privacy policy should be available via a link and clearly describe data collection.

Testing on real devices before release is mandatory. Emulators do not always correctly display the behavior of the application on different versions of Android and different smartphone models. Use the app Google Play Console for closed testing among a limited group of users.

⚠️ Attention: Google Play Rules and requirements for API levels (Target SDK) are regularly updated. Before publishing, be sure to check the latest requirements in the developer console documentation so that your application is not rejected due to outdated security standards.

Frequently asked questions (FAQ)

Is it possible to create a game in Python for Android?

Yes, it is possible. The framework Kivy is great for creating 2D games. It supports multi-touch, graphics and sound. However, for complex 3D projects with high graphics, it is better to use engines like Unity or Unreal Engine, since Python's performance may not be sufficient.

Do you need to know Java to develop in Python for Android?

No, knowledge of Java is not required. You can write all the logic and interface in Python. However, a basic understanding of the structure of Android projects and how the operating system works will help you more effectively solve problems when debugging and building.

Why does my application weigh so much?

Along with your code, the Python interpreter and all the libraries that you imported are packaged in the APK. This is an inevitable cost for cross-platform. Use compression tools and remove unnecessary dependencies to buildozer.specto reduce the size a little.

Is it possible to update an application over the air without a store?

Yes, you can implement a self-updating mechanism within the application by downloading a new APK from your server. But to install a new version, the user will still have to confirm permission to install from unknown sources in the Android settings.

Does Python work on iOS the same way as on Android?

iOS support exists (through the same Kivy or BeeWare), but the build process is much more complicated due to the closed nature of the Apple ecosystem. You will need a computer with macOS and Xcode. In addition, the App Store policy is more strict towards interpreted languages, although applications in Python are published there.