Development of Android applications in Python

Mobile application development is traditionally associated with the Java or Kotlin languages, but the existence of Python in this niche has long ceased to be a myth. Many novice programmers dream of using already familiar syntax to create full-fledged apps that can be installed on a smartphone via Google Play. The ability to write logic in Python and compile it into an APK file opens the door to rapid prototyping and creating utilities without a deep dive into the Android Studio ecosystem.

Despite the fact that the native performance of Python is inferior to compiled languages, modern tools allow you to create completely working interfaces and functional backends. The key point here is the correct choice of a framework that will take on the task of rendering widgets and interacting with the device’s system APIs. You won't have to write JNI wrappers manually if you use specialized libraries created by the community.

In this article we will analyze in detail the main approaches to cross-platform development, compare popular tools and describe the process of assembling the finished product. You will learn the limitations of using an interpreted language on a mobile platform and how to effectively overcome them. Understanding these nuances will help you make an informed decision about the appropriate choice Python for your next commercial or pet project.

Choosing the right framework for mobile development

The first and most important step is to choose a tool that will translate your code into a format understandable for the Android operating system. Today, the leaders in this area are two main solutions: Kivy and BeeWare (in particular, the Toga library). Each of them has its own philosophy and approach to building a user interface, which directly affects the final appearance of the application.

Kivy uses its own rendering engine based on OpenGL ES. This means that your app will look the same on all devices, but it won't use standard Android controls like native buttons or input fields. This approach provides a high degree of design customization, but can create a feeling of “foreignness” of the app for a user accustomed to the standard system interface.

In contrast, the project BeeWare seeks to use native widgets of each platform. This allows the application to look like it was written in Java or Kotlin, integrating into the visual style of the smartphone. However, the framework's support for complex animations and custom controls may be limited compared to its flexibility. The choice depends on what is more important to you: a uniform design on all platforms or maximum compliance with Google guidelines. Kivy. The choice depends on what is more important to you: a uniform design on all platforms or maximum compliance with Google guidelines.

⚠️ Attention: The Kivy framework requires that you disable hardware acceleration in the emulator when testing on older versions of Android, as rendering artifacts may occur.

There are other less popular options, for example PyQt or SL4A, but their mobile platform support often lags or requires complex manipulation of the environment. For most interface building tasks, the community recommends focusing on two main leaders. Below is a comparative table that will help you make your choice.

Characteristics	Kivy	BeeWare (Toga)	Native development
Interface type	Native (OpenGL)	Native widgets	Native widgets
Difficulty of learning	Average	High (due to novelty)	High
Performance UI	High (60 FPS)	Medium	Maximum
APK file size	Large (includes interpreter)	Average	Minimum

Customization environment and installing the necessary tools

Before writing the first line of code, you need to prepare a working environment on your computer. Unlike desktop development, where you just need to install an interpreter, for Android you will need a set of specific utilities for cross-compilation. The main tool for building projects based on Kivy is Buildozer, which automates the process of creating an APK package.

Installation of Buildozer is only possible in a Linux or macOS environment, since it directly depends on the Android SDK and NDK command line tools. If you are running Windows, you will have to use an Ubuntu virtual machine or the WSL2 subsystem. This requirement is often a stumbling block for beginners, but it is necessary for the build chain to work correctly.

The setup process includes installing the Java Development Kit (JDK), Android SDK and Android NDK. The versions of these components must strictly match the requirements of your framework, otherwise the compilation process will fail. For example, for stable work with the latest versions Python-for-Android often requires a specific version of the NDK specified in the project documentation.

After installing all the dependencies, you create a configuration file buildozer.spec at the root of your project. This file contains application metadata such as title, package name, version, and a list of required permissions and dependencies. Correct configuration of this file is critical, since it is the file that dictates to the builder which libraries to include in the final image.

Creating a user interface in the KV language

In the Kivy ecosystem, a special markup language called KV Languageis used to describe interfaces. It allows you to separate the application logic written in Python from the visual representation, making the code much easier to maintain. The KV syntax is intuitive and reminiscent of YAML, which allows you to quickly layout screens without writing cumbersome procedural code.

You can create your own widgets by inheriting from base classes such as BoxLayout, GridLayout or ScrollView. This makes it possible to build complex interfaces with nested structures that adapt to different screen sizes of smartphones and tablets. Using class rules in KV files allows you to apply styling to your entire application centrally.

#:kivy 2.0.0

font_size: 20
color: 1, 1, 1, 1

:
background_color: 0.2, 0.6, 1, 1
color: 1, 1, 1, 1
bold: True

This is achieved through Kivy's properties and events engine, which automatically tracks data changes and updates the interface. This reactivity is the basis of the modern approach to UI development.

For those who prefer to write everything in pure Python, the framework also provides this opportunity, but the code becomes less readable when complication of the interface structure. Separating logic and presentation is considered a best practice that should be followed even in small projects. This will make it easier to further modify the design without the risk of breaking the business logic of the application.

Working with the hardware capabilities of a smartphone

One ​​of the main advantages of mobile applications is access to the unique functions of the device: camera, GPS, accelerometer and light sensors. In Python development, these functions are accessed through special extension packages such python-for-android or specific Kivy libraries. However, the implementation of this access may differ from the usual methods in native development.

To work with geolocation, you will need to request the appropriate permissions in the file buildozer.spec and use operating system services through wrappers. It is important to consider that in modern versions of Android, permissions are divided into normal and dangerous, requiring confirmation by the user at runtime. Your application must correctly handle situations when the user denies access to data.

• 📸 Access to the camera is implemented through a widget Camerathat displays the image stream, but saving photos will require additional logic for working with the file system.
• 📍 Geolocation is available through the provider gps, which returns coordinates in real time, but can significantly consume battery power if frequently requested.
• 📳 Vibration and sound are controlled through simple API calls, but require checking support for these functions on a specific device.

It should be noted that not all sensors may be available through standard libraries, and sometimes you have to write your own JNI modules in Java for accessing specific functions. This complicates the development process and requires knowledge of both platforms. However, for most standard tasks, the existing tools are quite sufficient.

⚠️ Attention: When working with background services (for example, GPS tracking in the background), make sure that you configure the Android power saving settings correctly, otherwise the system may kill your process.

File system access restrictions

Starting with Android 10, access to shared folders is severely limited by the Scoped Storage policy. You may need to use the Storage Access Framework to work with user files.

The process of compiling and building an APK file

The final stage of development is turning your script into an installation package. The command buildozer android debug starts a long process that downloads dependencies, compiles Python code into bytecode, packages resources, and signs the application. The first launch may take considerable time due to the loading of the Android SDK and NDK.

During the build, you may encounter C library compilation errors if some Python dependencies do not have ready-made recipes for cross-compilation. In this case, you will have to create recipes yourself or look for alternative libraries that are supported by the community. A successful build ends with the creation of a file .apk in the directory bin.

To publish on the Google Play Store, you will need to create a signed release version of the application. This is done using the command buildozer android release and the presence of a keystore file with signing keys. Losing this key means you won't be able to update the app in the future, so keep it in a safe place.

The size of the resulting APK file is usually significantly larger than the size of a similar native app, since it includes the entire Python interpreter and necessary libraries. This is a price to pay for ease of development and cross-platform functionality. Size optimization is possible by removing unused modules and compressing resources, but it will not be possible to completely get rid of overhead costs.

Performance optimization and publishing

After receiving a working APK, you need to focus on optimization. Python is an interpreted language, which may result in computational and interface delays. For critical sections of code, it is recommended to use libraries written in C, or move heavy calculations to separate threads so as not to block the main UI rendering thread.

Application profiling can be done using built-in Kivy tools or third-party utilities. Finding bottlenecks in the code allows you to improve the responsiveness of the interface. It is also worth paying attention to memory consumption, since mobile devices have more stringent limitations compared to desktops.

When preparing for publication, carefully study the Google Play Console requirements. Your application must comply with security policies, especially regarding data collection and permission usage. Errors in the manifest or incorrect handling of access rights may cause moderation to be rejected.

• ⚡ Use asynchronous programming for network requests so that the interface does not freeze while loading data.
• 🗑️ Clear the application cache regularly so that it does not take up too much space on the user's device.
• 🔒 Encrypt sensitive data stored locally using strong encryption algorithms.

⚠️ Note: Google Play policies are updated regularly. Before publishing, be sure to check the target API level requirements (targetSdkVersion) in the official developer document.

Frequently asked questions

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

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

How much slowdown will a Python application be compared to Java?

For typical tasks (forms, lists, working with the network), the difference is invisible to the user. Brakes can only occur during intensive mathematical calculations in the main thread or during complex animation of many objects.

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

For basic development, knowledge of Java is not required. However, it will be a big plus if you have to write your own modules to access specific Android APIs that are not covered by the standard Python libraries.

Is it possible to update an application written in Python via Google Play?

Absolutely. The update mechanism works as standard: you download a new version of the APK with an increased version number (versionCode), and users receive the update as usual.