Android Developer Roadmap 2024 | Master Kotlin & Jetpack Compose

Android – A name that is now part of life of billions people on earth. According to a statistics android hold 73% smartphone market share. Android has 1.6 billion users world wide. Have a look on below data which is enough to get you into the realm on android.

• Android dominates countries like Brazil, India, Indonesia, Vietnam, and Turkey, where its market share exceeds 85%.
• As of March 2023, the Google Play Store had 2.67 million apps available.
• TikTok is the most downloaded app on Android, with 24 million downloads, followed by Instagram and WhatsApp Messenger.
• The highest-earning app on Android is Coin Master, generating USD 47.96 million in revenue.
• 97% of Android apps are free, while only 3.1% are paid apps.
• Android became the most popular mobile OS in 2014, reaching 1 billion users in just one year.
• Android’s user base peaked in 2018, with steady growth since its launch.
• Samsung holds the largest share of the Android market, with 14.5%, followed by Xiaomi.

As you already know android is becoming our body part due to its day to day use in our life. Android is makes our life easy with its apps. It is not the Android OS that makes our life smooth but its the Apps that has changed everything. As android grows so does its users that will create need for more android developers. So its the best time to get into the realm of Android App development.

In this article I will explain in steps about the complete android development roadmap which should be followed to become a successful android development.

What is Android

Android is a mobile operating system developed by Google, designed primarily for touchscreen devices like smartphones and tablets. It powers millions of devices worldwide and is built on the Linux kernel, making it open-source, flexible, and highly customizable.

Key Features of Android

1. Open Source: Developers can modify and build their own versions of Android.
2. Wide Ecosystem: It supports a variety of apps and services through the Google Play Store.
3. Customizability: Users and manufacturers can personalize the interface, features, and functionality.
4. Versatile Use: Beyond phones, Android is used in TVs, smartwatches, cars, and even home appliances.

Why is Android Important?

• Popularity: Android powers over 73% of the world’s smartphones.
• Opportunities: It creates a thriving ecosystem for developers to build apps for billions of users.
• Diverse Career Paths: Android developers work on apps, games, and systems for various industries.

This makes Android an exciting platform for developers to learn, grow, and create amazing user experiences.

Best way to Learn Android

The best way to learn any technology is through courses online/offline, reading books and today’s common You tube videos. But only reading or watching videos doesn’t make you a better android developer. The best way to learn and retain something in mind forever is to implement it in real life. In case of coding is pretty much similar. You need to code as much as you can to grasp the technology early. Making projects is the best practice you can choose to learn any programming technology.

Steps to Become Android Developer

Step 1. Choose Development Field –

1. Native Development

In native development, app are built for specifically one platform either for android or iOS separately. Each field has its different technology to build apps for its environment. Apps made for one platform will work only on that platform.

1. Android – To build apps for android platform we use Kotlin or Java programming languages.
2. iOS – To build iPhone apps we can use Swift or Objective-C programming languages.

This development has some pros like high performance, high stability, better user experience and cons like higher cost and longer development time due to write two separate code bases.

2. Cross-Platform

In this type of development apps are made common for both android and iOS. Apps made with cross platform technology will run on both platforms. You will write code once and that will work for both Android and iOS.

1. Flutter – It is famous framework used in making cross-platform apps with dart programming language.
2. React Native – It is also a framework for making apps with JavaScript or TypeScript programming languages.

Cross-platform apps has some pros like single codebase and cost efficient but has some cons also like performance issues and limited access to platform specific features.

Step 2. Choose Programming Language

In Android, programming is done in two languages JAVA or Kotlin and XML(Extension Markup Language). The XML file deals with the design, presentation, layouts, blueprint, etc (as a front-end) while the JAVA or KOTLIN deals with working of buttons, variables, storing, etc (as a back-end).

Java or Kotlin?

Kotlin is the official language for Android App Development Declared by Google  and it is the most used language as well. Many of the apps in the Play Store are built with Kotlin and it is also the most supported language by Google. Kotlin is fast and easy than java. Kotlin also include Lot of new features and libraries that is not present in Java. 

Java is the native language used by Android, applications that helps to communicate with the operating system and  hardware that directly uses Java. This language allows the creation of any program and supports almost all types of machines, and OS X be it Android, Windows, or Linux.  Java was developed by Sun Microsystems (now the property of Oracle) and one can use Microservices with Java.

Kotlin is a cross-platform programming language that can be used as an alternative to Java for Android App Development. It has also been declared  “official” language by google . The only sizable difference is that Kotlin removes one of the features of Java such as null pointer exceptions. It also removes the use of semicolon at the end of every line . In short, Kotlin is much simpler for beginners as  compared to Java and Now most of developer also shift from java to Kotlin for Android App Development.

Learn Language Fundamentals

If you have decided any language which should be Kotlin in case of Android for obvious reasons then you should learn at least the basics it. You don’t need to learn from A-Z of that language but have basic ideas about the following-

1. Variables – Where the smallest data entity stored in memory
2. Data Types – What type of data we can store using this language like numbers, letters etc
3. Conditionals – These are the condition base features of language like if-else
4. Loops – These are the ways in a language which help use to run some condition multiple times
5. OOPs Concepts – This is a advance topic of a language but if you have an idea then well and good.

Step 3. Integrated Development Environment

As the name suggest, you need some kind of environment for android development which is a software based tools that help us to make apps easily. The basic purpose of IDEs is to make our development easy like auto code completions, run time errors, code suggestions, code compilations, app building, code testing and debugging. So, for android we use Android Studio for our code companion.

To start with Android Studio you need to have an Idea about the following

1. Hardware Requirement – Android studio need min 8GB of RAM and higher variant of processors than i3 to make its functioning smooth.
2. File Structure- You should have an basic Idea about how studio store apps file or what are all apps files that you need to deal with.
3. API Levels – As any software or app has new versions betters and more efficient than their previous counter parts, same android also has its versions which are named as API levels. With each newer Versions new API levels are launches by android to make android more better and secure than previous.
4. Gradle – It is a build automation tool which that will compile and wrap up you app into a final apk file that can be run on any android device.
5. Android Virtual Device – It is smart phone built in into android studio itself which can be used for testing apps but this is a virtual device so its performance is very leggy.

Version Control System – Git

Git is a version control system which will controls the versions of you code base as you make some improvement in you code. As you add more and more features in app then its version should also increase along with maintaining the history of previous versions. Some time you need to go back to your previous code than Git will take you back into code history.

Step 4. Android Platform Architecture

The Android platform architecture is the underlying structure of the Android operating system, designed to provide a flexible and secure environment for app development and execution. It consists of several layers, each with specific components and responsibilities.

Main Parts of Android Platform Architecture:

1. Linux Kernel:

• Acts as the foundation of the Android platform.
• Handles core system functionalities like device drivers, memory management, power management, and networking.
• Ensures communication between hardware and software.

2. Hardware Abstraction Layer (HAL):

• Provides standard interfaces for hardware-specific implementations.
• Allows the Android framework to interact with hardware components (like camera, Bluetooth, etc.) without needing to know their low-level details.

3. Android Runtime (ART):

• Executes and manages apps.
• Includes the Core Libraries (providing essential APIs for app development) and the ART Virtual Machine, which converts app code into machine-readable instructions.

4. Native C/C++ Libraries:

• Offers core functionalities for media playback, graphics rendering, databases, and more.
• Examples include OpenGL (for graphics), SQLite (for databases), and Libc.

5. Android Framework:

• Provides a set of reusable tools and services for app development.
• Includes components like Activities, Services, Content Providers, and Broadcast Receivers.
• Manages key system services like location, notifications, and UI rendering.

6. Application Layer:

• This is where Android apps run.
• Developers create apps using the Android framework, which interacts with lower layers to deliver functionality.
• Apps are typically written in Kotlin, Java, or C++.

Step 5. Android Main Components

Android components are the building blocks of an Android app. They define how an app interacts with the user, other apps, and the system. There are four main components in Android:

1. Activities:

• Represent a single screen in an app.
• Used for user interaction (e.g., a login page or a settings screen).
• Each activity has its own lifecycle (e.g., start, pause, resume, stop).
• Example: The main screen of a shopping app where users browse products.

2. Services:

• Perform background tasks without a user interface.
• Used for operations like playing music, downloading files, or syncing data.
• Runs even if the app is not visible.
• Example: A music app playing songs in the background.

3. Broadcast Receivers:

• Listen for system-wide messages or events.
• Used to respond to notifications like battery low, network changes, or incoming SMS.
• Can also trigger app-specific tasks.
• Example: An app receives a notification when the phone connects to Wi-Fi.

4. Content Providers:

• Manage data sharing between apps or within the app.
• Allow apps to access data like contacts, media, or custom databases.
• Example: A messaging app accessing the phone’s contact list.

Supporting Components:

• Intents: Used to communicate between components (e.g., starting an activity or service).
• Fragments: Subsections of an activity, used for building dynamic and reusable UI components.

Step 6. UI Components

Here’s a detailed comparison of Android UI components in XML and their corresponding counterparts in Jetpack Compose, grouped into categories like elements, layouts, navigation, and others.

1. Basic UI Elements

Text

• XML: <TextView>
  • Used to display text.
• Jetpack Compose: Text()
  • A composable function to display text.

Button

• XML: <Button>
  • A clickable button.
• Jetpack Compose: Button(onClick = { }) { Text("Button") }
  • Provides click handling and customization.

Image

• XML: <ImageView>
  • Displays an image.
• Jetpack Compose: Image(painter = painterResource(id = R.drawable.image), contentDescription = "")
  • Displays an image with more control.

EditText (Input Field)

• XML: <EditText>
  • For user input.
• Jetpack Compose: TextField(value = "", onValueChange = { })
  • Provides input handling with modern styling.

CheckBox

• XML: <CheckBox>
  • Allows users to select or deselect an option.
• Jetpack Compose: Checkbox(checked = true, onCheckedChange = { })
  • A composable checkbox.

RadioButton

• XML: <RadioButton>
  • Used for single-choice selection.
• Jetpack Compose: RadioButton(selected = true, onClick = { })
  • Works similarly for radio groups.

Switch

• XML: <Switch>
  • A toggle switch for enabling/disabling options.
• Jetpack Compose: Switch(checked = true, onCheckedChange = { })
  • Modern toggle component.

ProgressBar

• XML: <ProgressBar>
  • Displays a loading spinner or progress.
• Jetpack Compose: CircularProgressIndicator() or LinearProgressIndicator()
  • Used for circular or linear progress indicators.

Floating Action Button (FAB)

• XML: <com.google.android.material.floatingactionbutton.FloatingActionButton>
  • A button for primary actions.
• Jetpack Compose: FloatingActionButton(onClick = { }) { Icon(...) }
  • Easy to customize.

2. Layouts

Linear Layout

• XML: <LinearLayout>
  • Arranges children in a vertical or horizontal direction.
• Jetpack Compose: Column { ... } or Row { ... }
  • Vertical (Column) or Horizontal (Row) arrangement.

Relative Layout

• XML: <RelativeLayout>
  • Positions children relative to each other.
• Jetpack Compose: Box { ... }
  • Use modifiers like align() for relative positioning.

Constraint Layout

• XML: <ConstraintLayout>
  • Flexible and powerful layout system.
• Jetpack Compose: ConstraintLayout { ... }
  • Compose has a ConstraintLayout equivalent.

Frame Layout

• XML: <FrameLayout>
  • Stacks children on top of each other.
• Jetpack Compose: Box { ... }
  • Works the same for stacking elements.

Grid Layout

• XML: <GridLayout>
  • Displays items in a grid.
• Jetpack Compose: LazyVerticalGrid(...)
  • For grids with lazy item loading.

ScrollView

• XML: <ScrollView>
  • Allows scrolling for vertical content.
• Jetpack Compose: Column(Modifier.verticalScroll(rememberScrollState()))
  • Enables vertical scrolling.

RecyclerView

• XML: <RecyclerView>
  • Displays a list of items efficiently.
• Jetpack Compose: LazyColumn { items(...) { ... } }
  • A composable list with lazy loading.

3. Navigation Components

NavigationView

• XML: <NavigationView>
  • For navigating between screens.
• Jetpack Compose: NavHost(...) with NavController
  • Compose navigation with Jetpack Navigation.

Bottom Navigation

• XML: <com.google.android.material.bottomnavigation.BottomNavigationView>
  • A bar at the bottom for switching tabs.
• Jetpack Compose: BottomNavigation { ... }
  • Similar tab-based navigation.

TabLayout

• XML: <TabLayout>
  • Displays tabs for switching views.
• Jetpack Compose: TabRow { ... }
  • Allows tab-based navigation in Compose.

4. Additional UI Components

Dialog

• XML: Handled programmatically with AlertDialog.Builder.
• Jetpack Compose: AlertDialog(onDismissRequest = { }) { ... }
  • Direct composable for dialog UI.

Card

• XML: <androidx.cardview.widget.CardView>
  • Displays content inside a card.
• Jetpack Compose: Card { ... }
  • Easily creates card UIs.

Snackbar

• XML: Handled programmatically with Snackbar.
• Jetpack Compose: Snackbar { ... }
  • Shows snackbars directly.

ToolBar

• XML: <Toolbar>
  • A customizable action bar.
• Jetpack Compose: TopAppBar { ... }
  • Equivalent for app bars.

Bottom Sheet

• XML: <BottomSheetDialog>
  • Displays modal bottom sheets.
• Jetpack Compose: ModalBottomSheetLayout { ... }
  • Compose alternative for bottom sheets.

Toast

• XML: Handled programmatically with Toast.makeText.
• Jetpack Compose: Toast is still called programmatically.

Step 7. Android Storage

Internal Storage in Android

Internal storage is a private storage space allocated to an app within the device’s memory. Data stored here is accessible only by the app that created it, ensuring privacy and security.

Features:

1. Private to the App: Files are stored in the app’s sandbox directory (/data/data/<package_name>).
2. Secure: Other apps cannot access these files without root permissions.
3. Data Removal: Data is deleted when the app is uninstalled.
4. Access Methods:
   • openFileOutput() for writing files.
   • openFileInput() for reading files.

Best Uses:

• Storing sensitive information like user credentials.
• Temporary files that do not need to be shared with other apps.

External Storage in Android

External storage refers to a device’s shared memory (e.g., an SD card or emulated external storage) that allows data to be accessible across multiple apps or by the user directly.

Features:

1. Shared with Other Apps: Files can be accessed by other apps and users.
2. User-Visible: Data is stored in the device’s shared folders, such as Downloads, Pictures, or Music.
3. Less Secure: Files are not sandboxed, so they can be accessed or modified by other apps (with permission).
4. Access Methods:
   • getExternalFilesDir() for app-specific external files.
   • Environment.getExternalStorageDirectory() for shared files.

Best Uses:

• Media files like photos, videos, or music.
• Files the user should access directly (e.g., exported reports, downloads).

Comparison Between Internal and External Storage

Android provides several ways to store data based on the app’s requirements. Here’s a summary:

1. SharedPreferences

• Purpose: Store small key-value pairs (e.g., settings or user preferences).
• Storage: XML file.
• Usage: getSharedPreferences() for retrieving and storing data.
• Best for: Simple settings like “dark mode enabled” or “user logged in”.

2. Internal Storage

• Purpose: Store private files that only the app can access.
• Storage: Stored in the app’s sandbox directory (/data/data/<package_name>/files).
• Usage: openFileOutput() and openFileInput().
• Best for: Sensitive data or files specific to the app.

3. External Storage

• Purpose: Store files that users can access outside the app (e.g., media files).
• Storage: Device’s external memory (e.g., SD card or shared storage).
• Usage: getExternalFilesDir() or Environment.getExternalStorageDirectory().
• Best for: Media files, downloads, or user-exported data.

4. SQLite Database

• Purpose: Store structured data in tables with SQL queries.
• Storage: Internal app storage.
• Usage: Use the SQLiteOpenHelper class for database operations.
• Best for: Complex and relational data, such as a contact list or inventory.

5. Room Database

• Purpose: A modern abstraction over SQLite with added benefits like type safety.
• Storage: Internal storage using SQLite as the backend.
• Usage: Define entities and access data using DAOs (Data Access Objects).
• Best for: Structured and large-scale local data with an ORM approach.

6. Content Providers

• Purpose: Share data between apps.
• Storage: Can access SQLite, files, or other internal data.
• Usage: Create a ContentProvider subclass and use URIs for access.
• Best for: Sharing files, contacts, or other app data securely.

7. Cache Storage

• Purpose: Temporarily store frequently accessed data for better performance.
• Storage: App-specific cache directory.
• Usage: Use getCacheDir() or getExternalCacheDir().
• Best for: Temporary data like images or network responses.

8. DataStore

• Purpose: Modern replacement for SharedPreferences.
• Storage: Uses either Preferences or Proto for key-value or typed storage.
• Usage: Leverages Kotlin Coroutines for asynchronous operations.
• Best for: Storing small, reactive data like user preferences.

Step 8. Android Local APIs

1. AlarmManager

• Purpose: Schedule tasks or actions to run at specific times, even if the app is not active.
• Usage: getSystemService(Context.ALARM_SERVICE).
• Examples:
  • Sending daily reminders.
  • Triggering background sync at night.

2. LocationManager

• Purpose: Retrieve device location using GPS, Wi-Fi, or cellular networks.
• Usage: getSystemService(Context.LOCATION_SERVICE) and request updates.
• Examples:
  • Fetching user location for maps or weather apps.
  • Location-based notifications.

3. ConnectivityManager

• Purpose: Monitor and manage network connectivity.
• Usage: getSystemService(Context.CONNECTIVITY_SERVICE) and check network state.
• Examples:
  • Detecting if the user is connected to Wi-Fi or mobile data.
  • Managing offline/online modes in apps.

4. PowerManager

• Purpose: Manage power states and battery optimization.
• Usage: getSystemService(Context.POWER_SERVICE).
• Examples:
  • Keeping the screen on during a video call.
  • Managing wake locks for background tasks.

5. SensorManager

• Purpose: Access device sensors like accelerometer, gyroscope, and proximity.
• Usage: getSystemService(Context.SENSOR_SERVICE) to retrieve sensor data.
• Examples:
  • Fitness tracking apps (step counter).
  • Tilt-based gaming controls.

6. NotificationManager

• Purpose: Manage and display system notifications.
• Usage: getSystemService(Context.NOTIFICATION_SERVICE).
• Examples:
  • Sending alerts for messages or updates.
  • Displaying progress notifications for downloads.

7. ClipboardManager

• Purpose: Copy and paste data between apps or views.
• Usage: getSystemService(Context.CLIPBOARD_SERVICE).
• Examples:
  • Copying text from a message to a browser.
  • Managing clipboard history in apps.

8. Vibrator

• Purpose: Trigger vibrations for feedback or alerts.
• Usage: getSystemService(Context.VIBRATOR_SERVICE).
• Examples:
  • Haptic feedback for button clicks.
  • Alerting users for notifications.

9. AudioManager

• Purpose: Manage audio settings and streams.
• Usage: getSystemService(Context.AUDIO_SERVICE).
• Examples:
  • Adjusting media, ringer, or alarm volume.
  • Switching between audio outputs (speaker or Bluetooth).

10. PackageManager

• Purpose: Interact with installed apps and their components.
• Usage: getPackageManager().
• Examples:
  • Checking if another app is installed.
  • Launching an app via its package name.

Step 9. Android Design & Architecture

• Design: Focuses on user-friendly UI/UX following Material Design guidelines, ensuring consistency, intuitive navigation, and responsive layouts.
• Architecture: Android follows a layered architecture:
  • App Layer: Built with MVVM, MVP, or MVI for separation of concerns.
  • Libraries Layer: Jetpack libraries for lifecycle, navigation, and more.
  • Framework Layer: Manages UI, permissions, and resource access.
  • Linux Kernel: Handles hardware and system services.

Step 10. Code Analysis & Testing

• Code Analysis: Tools like Lint and SonarQube ensure code quality by identifying performance, security, and style issues.
• Testing:
  • Unit Testing: Tests logic using JUnit and Mockito.
  • UI Testing: Automates UI flows with Espresso.
  • Integration Testing: Ensures components work together.
  • Firebase Test Lab: Tests apps on real devices in the cloud.

Step 11. App Distribution

• Play Store: Primary distribution platform with tools for app reviews, beta testing, and analytics.
• APK/AAB: Apps are packaged as APK (traditional) or AAB (modern for optimized delivery).
• Alternative Channels: Includes third-party stores (e.g., Amazon Appstore) or direct APK sharing.

This is all about android roadmap, you can refer my flow chart for more reference here