Android development: what you need to know before starting

The world of mobile development is huge, and entering it often seems daunting due to the abundance of technologies and rapidly changing standards. However, if you want to create applications for the most popular operating system in the world, you will have a fascinating journey of learning tools and patterns. Android development Today is fundamentally different from what it was five years ago, shifting the focus from imperative programming to declarative interfaces.

Before you write the first line of code, you need to understand that the Google ecosystem requires the developer not only to know the syntax, but also to have a deep understanding of the application life cycle. You will have to work with Android Studio, understand gradle scripts and constantly monitor updates to Jetpack libraries. This is not just writing code, it is creating sustainable architectural solutions that will work on thousands of different devices.

In this article we will analyze the fundamental knowledge without which it is impossible to become a sought-after specialist. We will touch on the choice of programming language, setting up the environment and key architectural components that form the basis of modern projects.

Choosing a programming language: Kotlin vs Java

For a long time, the main language for creating mobile applications was Java, and a huge amount of legacy code is still written in it. However, since 2019, Google has announced an approach Kotlin-first, making this language a priority for all new developments. If you are just starting your journey, there is practically no question of choice - learn Kotlin.

This language has strong typing, eliminates routine code (for example, you do not need to write getters and setters manually) and protects against common errors such as NullPointerException. Kotlin syntax is more concise and expressive, which allows you to focus on application logic rather than template constructs.

⚠️ Attention: Learning Java can still be useful for reading old documentation or supporting legacy projects of large banks, but for starting new products it is an unjustified waste of time.

In addition, modern libraries from Google, such as Jetpack Compose and Coroutinesare initially developed taking into account the capabilities of Kotlin. Using Java in conjunction with new tools often leads to the need to write additional wrapper code (boilerplate code), which complicates project support.

It is important to understand that knowing one language is not enough. You will need to understand how this language interacts with the virtual machine ART (Android Runtime) and how memory is managed. Garbage Collector Android works differently than in desktop applications, and incorrect reference management can lead to memory leaks and application crashes.

Setting up the development environment and tools

The main working environment for any Android developer is Android Studio. It is a powerful IDE based on IntelliJ IDEA that provides all the necessary tools for writing, debugging and testing code. Installing the environment is the first step, which can be difficult for beginners due to the need to configure emulators and SDKs.

You will need to install Android SDK (Software Development Kit), which contains platforms, build tools and system images. In the SDK manager, you should select the latest stable versions of the API, but it is also useful to have images of older versions on hand to check compatibility.

Particular attention should be paid to the emulator. While testing on real devices is always preferable, an emulator allows you to quickly test UI changes on different screen resolutions. Modern versions of the emulator support acceleration via Hyper-V or HAXM, which makes their operation almost indistinguishable from a real phone.

Do not forget about the version control system. S Git integration is built into Android Studio, and the use of branches to develop new features is an industry standard. Never write code directly to the main branch without a code review.

Architecture fundamentals and application components

Understanding architecture is what distinguishes a professional from an amateur. An application should not be a monolithic piece of code; it must be divided into logical layers. In modern development, the de facto architecture has become the MVVM (Model-View-ViewModel) architecture, which clearly separates display logic and business logic.

The key components of any application are Activity and Fragment. An Activity is a single screen with an interface, and a Fragment is a modular part of the interface that can be used inside an Activity. Improper management of their life cycle is the most common cause of bugs.

Component	Purpose	Features of the life cycle
Activity	Represents a single screen with UI	Manages a window, responds to screen rotations
Fragment	Behavior or part of the UI in an Activity	Has its own life cycle, depending on host
Service	Perform operations in the background	Works without an interface, important for long tasks
BroadcastReceiver	Reaction to system events	Started by the system when an event occurs

The system is used to store data and transfer information between components Intent. This is a message object that can be explicit (indicates a specific class) or implicit (describes an action to be performed by the system). Understanding how Intents work is critical to navigating between screens.

What is the Activity lifecycle?

The Activity lifecycle includes states: Created, Started, Resumed, Paused, Stopped, Destroyed. The developer must correctly handle transitions between them to save data when the screen is rotated or the application is minimized, otherwise the user will lose the entered information.

Working with user interface (UI)

Creating interfaces is undergoing a revolution. The traditional approach using XML markup is gradually becoming a thing of the past, giving way to a declarative framework Jetpack Compose. If earlier you described the screen structure in a separate file and linked it with code via findViewById, now the interface is described directly in the Kotlin language.

Compose allows you to create complex animations and adaptive interfaces with much less code. Composables react to state changes automatically, which eliminates a whole class of errors associated with data and display desynchronization.

However, knowledge of XML is still required, since many existing projects and some third-party libraries do not yet support Compose 100%. You need to be able to work with ConstraintLayout, RecyclerView and theme systems (Themes & Styles).

⚠️ Attention: When designing the interface, always take into account the variety of screens. What looks beautiful on Pixel 8 Promay break on a budget smartphone with a small screen. Use dp (density-independent pixels) instead of pixels for padding and sizes.

Adaptability is a key trend. Your application should work correctly not only on phones, but also on tablets, foldable devices and even on car screens (Android Auto). To do this, you need to study the principles Material Design 3that offer ready-made guidelines for adapting interfaces to different form factors.

Data storage and network interaction

Any modern application interacts with the outside world in one way or another: downloads news, sends forms, synchronizes data. The standard for working with the network is the library Retrofit. It allows you to describe HTTP requests as interfaces, automatically converting JSON responses into Kotlin objects.

A database Roomis used to locally store data that should be saved after the application is closed. This is a wrapper over SQLite that provides convenient work with data through annotations. Room checks SQL queries at the compilation stage, which prevents many runtime errors.

Here is an example of what an entity description for a database might look like:

@Entity(tableName = "users")
data class User(
@PrimaryKey val id: Int,
val name: String,
val email: String
)

In addition, DataStoreis used to store simple settings (for example, a theme or an authorization token). The old mechanism SharedPreferences is considered obsolete and is not recommended for use in new projects due to performance problems when working in the main thread.

Publishing and monetizing applications

When the application is ready, it needs to be prepared for publication in Google Play. This process requires creating a developer account, paying a one-time fee, and carefully filling out metadata. The app store has strict security and content policies, violation of which leads to a ban.

You will need to prepare graphic assets: an application icon, screenshots for different types of devices and promotional videos. A Privacy Policy is also required, especially if the application collects any user data.

• 📱 App signature: Each APK or AAB file must be signed with a digital key. Keep this key in a safe place, its loss will make it impossible to update the application in the future.
• 💰 Monetization: Select a model: paid download, In-App Purchases or advertising through AdMob. Integration of Google Play Billing Library is required for sales of digital goods.
• 📊 Analytics: Connect Firebase Analyticsto understand how users interact with your product, where they fall off and what functions they use most often.

The moderation process on Google Play can take from several hours to several days. Often applications are returned for revision with specific violations of the rules indicated. Be prepared to promptly respond to reviewers' comments.

⚠️ Attention: Google Play rules change frequently. Be sure to check the Target SDK Level requirements before each publication. Applications that are not updated to meet new security requirements may be hidden from search or deleted.

Frequently asked questions (FAQ)

How long does it take to become a Junior Android developer?

With intensive training (4-6 hours a day), the basic level is achieved in 6-9 months. However, it is important not just to take courses, but to create 2-3 full-fledged pet projects for a portfolio that demonstrate knowledge of architecture and working with the network.

Do you need to know mathematics to develop for Android?

For most business applications (shops, social networks, utilities), the school curriculum is enough. Higher mathematics will be required only in specific niches: game development, working with graphics, AR/VR or complex encryption algorithms.

Is it possible to develop for Android on Mac or Linux?

Yes, Android Studio is cross-platform. Moreover, to build iOS versions of applications (if you decide to become a cross-platform developer), a Mac is required, since Xcode only works on macOS.

What are ProGuard and R8 and why you need them?

These are code obfuscation and optimization tools. They reduce the size of the APK file and make it difficult to reverse engineer (decompile) your application by renaming classes and methods into unintelligible symbols.