Creating your own software product for the most popular mobile operating system in the world is an ambitious task that opens the door to the world of high technology. Millions of users interact with mobile applicationsdaily, and your creation can become a part of their lives, solving specific problems or providing entertainment. The development process seems complicated only at first glance, but with the right approach and basic programming knowledge, anyone can master this skill.
In this article we will analyze in detail the entire path of the developer: from installing the necessary software to publishing the finished product in the store. Google Play. You will learn which programming languages are relevant today, how to set up a working environment, and which steps cannot be skipped in order to create a quality product. Even if you have never written code before, structured information will help you take your first confident steps in Android development.
The modern market dictates high demands on user experience and performance. Therefore, it is important not just to “write code”, but to create a thoughtful architecture that will work stably on thousands of different devices. Ready to dive into the world of app creation? Then let's start with choosing tools.
Preparing the working environment and choosing tools
The first step towards creating an application is to install an integrated development environment (IDE). Today, the de facto standard is Android Studio, the official environment from Google, based on the IntelliJ IDEA platform. It provides all the tools you need to write code, debug, profile, and emulate devices right on your computer. You can download it for free from the official website of the developers.
In addition to the development environment itself, you will need to install the development kit Android SDK (Software Development Kit). In modern versions Android Studio this process is automated: upon first launch, the installation wizard will offer to download the necessary platform components, emulators and system images. Make sure you have enough free space on your hard drive, as the full package can take up several gigabytes.
A Java Development Kit (JDK) is also critical, although newer versions of the studio often come with a built-in version of OpenJDK. You can use the command line to check whether the environment variables are set correctly. Enter the command to check the Java version:
java -versionIf the system displays a version number, then the environment is ready to use. Otherwise, you will need to manually configure system variables JAVA_HOME and PATH. Correctly setting up the environment will save you from many compilation errors in the early stages of learning.
⚠️ Attention: The versions of SDK components and emulators are constantly updated. Before starting a new project, check the official Google documentation to ensure that you are using compatible versions of the Gradle API and build tools.
To get started, it is recommended to create a simple "Hello World" project to verify that the emulator starts correctly and the application installs without errors.
Choice of programming language: Kotlin vs Java
For a long time, the main language for Android development was Java. It is a powerful, strongly typed language with a huge library ecosystem and community. However, in 2017, Google officially declared Kotlin the priority language for development for Android. Today, most new projects are created in Kotlin due to its conciseness, security and excellent compatibility with existing Java code.
Kotlin eliminates many of the problems inherent in Java, for example, the famous error NullPointerExceptionthanks to built-in support for Nullable types. Kotlin syntax allows you to write less code (boilerplate code) to perform the same tasks, which significantly speeds up the development process. It also supports functional programming and has excellent support from modern tools Android Studio.
However, knowledge of Java remains a useful skill. Many old projects, libraries and code examples on the Internet are written in it. If you plan to support legacy code or work in a large corporation with complex infrastructure, understanding the basics of Java will be an advantage. However, for a beginner starting from scratch, choosing Kotlin is the most rational decision.
It is important to note that both languages are compiled into bytecode, which is executed by the Android virtual machine Runtime (ART). This means that the performance of Kotlin and Java applications is almost identical. The choice depends solely on the ease of development and the requirements of a particular project.
Application architecture and main components
Any Android application is built on the basis of four main types of components, each of which plays its own unique role in the app life cycle. Understanding their purpose is the key to creating a stable and logical product. The developer must clearly understand how these parts interact with each other through interprocess communication mechanisms.
The central element of the interface is Activity (Activity). It is a single screen with a user interface. For example, in the messenger one activity can display a list of chats, and another - a correspondence window. Activities have a complex life cycle, including states of creation, pause, stopping and destruction, which must be handled competently in the code.
To perform background tasks that do not require user interaction, Services (Services) are used. They can work even after the user has minimized the application or switched to another task. Typical examples of using services are playing music, downloading files, or tracking geolocation.
The table below shows the main components and their purpose:
| Component | Purpose | Use example |
|---|---|---|
| Activity | Representation of user interface | Login screen |
| Service | Background execution of tasks | Data synchronization |
| Broadcast Receiver | Reaction to system events | Response to low battery |
| Content Provider | Access control to data | Reading contacts from the phone book |
Another important component is Broadcast Receiver (Broadcast message recipient). It allows an application to respond to events that occur on the system or in other applications, such as a change in network status or the completion of a file download. There are also Content Providersthat provide structured data access for other applications.
Proper use of the Activity lifecycle prevents memory leaks and application crashes when rotating the screen or switching between tasks.
Creating a user interface (UI)
The visual part of the application is created with using markup language XML or declarative toolkit Jetpack Compose. The traditional XML approach allows you to describe the structure of the screen, arranging (Views) such as buttons, text fields and images. This method is well studied and has many ready-made solutions, but can be verbose.
Jetpack Compose is a modern tool that allows you to build an interface directly in the Kotlin language. It uses a reactive approach: the interface automatically updates when the state of the data changes. This greatly simplifies the creation of complex and animated interfaces, reducing the amount of code and the likelihood of errors. For new projects, Google strongly recommends using it Compose.
When designing the interface, it is necessary to take into account the variety of screens of Android devices. Your application should be displayed correctly on both compact smartphones and large tablets. This is done using adaptive layouts, constraint chains (ConstraintLayout) and resources of alternative sizes. Don't forget about the dark theme and support for different pixel densities.
⚠️ Attention: UI interfaces and libraries are evolving quickly. What was standard a year ago may be considered outdated today. Always check the status of libraries in the official Android Development guides before implementing them into your project.
The component Navigationis used for navigation between screens. It manages the stack of activities and fragments, ensuring smooth transitions and the back button working properly. Well-designed navigation is the key to a convenient user experience.
Working with data and network requests
Most modern applications are not isolated: they exchange data with the server or store information locally. For working with the network in Android, the standard library is Retrofit. It allows you to easily describe HTTP requests using annotations and automatically converts JSON server responses into programming language objects.
A database is used to store data locally Room, which is an abstraction over SQLite. Room simplifies working with SQL queries by checking their correctness at the compilation stage. This is a reliable solution for storing cache, user settings and offline content. An alternative for simple data can be SharedPreferences or a new mechanism DataStore.
An important aspect is asynchrony. Network requests and database operations should never be performed in the main thread (UI thread), otherwise the application will hang and the system will throw an ANR (Application Not Responding) error. To control threads, coroutines (Coroutines) in Kotlin or libraries like RxJava are used. They allow you to write asynchronous code that appears consistent and understandable.
What is an API?
API (Application Programming Interface) is a set of rules that allows one application to communicate with another. In mobile development, this is most often a way to retrieve data from a remote server.
When working with sensitive data, such as authorization tokens or passwords, you must use encrypted storage EncryptedSharedPreferences. Never store secrets in clear text in code or normal settings, as this creates security vulnerabilities.
Testing, Debugging and Publishing on Google Play
Before you show your application to users, it must be thoroughly tested. Android Studio provides powerful tools for unit testing and UI testing. The emulator allows you to test the application on different versions of Android and with different screen sizes without the need to have a fleet of physical devices. However, testing on real hardware is still necessary to check performance and work with sensors.
The debugging process is carried out using a tool Logcatthat displays system and application logs in real time. Log analysis helps to find the causes of crashes and incorrect behavior. Profiler is also useful for monitoring memory, CPU, and network usage, which helps optimize your application.
When the application is ready, the publishing stage begins. You will need to register in the developer console Google Play Consoleby paying a one-time fee. The publishing process involves creating an app page, uploading screenshots, a description, and a signed APK or AAB file. Please note that the format is now required Android App Bundle (.aab) to publish new applications.
☑️ Checklist before publishing
Moderation on Google Play can take from several hours to several days. Once approved, the application will be available for download by users around the world. Don't forget to monitor reviews and crash statistics to quickly release updates and fixes.
How long does it take to learn how to write applications?
Basic skills for creating a simple application can be mastered in 2-3 months of intensive training. For a Junior level developer capable of working in a team, it usually takes 6 to 12 months of practice and studying in-depth topics.
Do you need to know mathematics to develop for Android?
For most typical applications (news, social networks, utilities), a school mathematics curriculum is sufficient. Advanced mathematics is required only for developing games, augmented reality applications or complex graphics.
Is it possible to develop applications on a phone?
Technically, there are environments for programming on mobile devices, but they are extremely inconvenient for full development. To create high-quality applications, you need a computer with a full-fledged IDE, a large screen and a keyboard.
Is it free to publish applications on Google Play?
Registration of a developer account costs $25 (one-time). After payment, you can publish an unlimited number of applications without a monthly subscription, unlike some other platforms.