I’ll walk you through the entire Android app development process using Android Studio, from the very first setup step to publishing and maintenance — no code, only clear explanations and the full project folder structure with what every file/folder means and why it exists. I’ll also explain important concepts (build system, lifecycles, resources, app signing, testing, Play Store workflow, tooling, and best practices). I’ll assume you want a modern Android approach (Android Studio + Gradle + AndroidX + Jetpack), and I’ll point out alternatives when useful.
Machine & OS: Android Studio runs on Windows / macOS / Linux. Make sure you have enough RAM (8–16 GB recommended), disk space (tens of GB), and a recent CPU.
Install Android Studio: installer bundles the IDE and SDK manager. During install it will download the Android SDK, platform tools, and a default emulator image if you choose.
Java / JDK: Android Studio ships a compatible JDK; you rarely need to install one separately now. The JDK is used to compile Java/Kotlin bytecode.
SDKs & API levels: decide minimum SDK (minSdk) and target SDK. The SDK packages contain the Android platform libraries and emulator system images.
Version control: install Git and initialize repositories early. Always keep source in Git (or another VCS).
Google account: for Play Console to publish apps.
Plan app features & UX (wireframes).
Create a new Android Studio project (module(s), language Kotlin/Java).
Implement UI and app logic (Activities/Fragments/ViewModels).
Integrate data layer (network, database).
Handle resources (images, layouts, strings).
Run & debug on emulator and real devices.
Write tests (unit, integration, UI).
Polish (performance, battery, accessibility, localization).
Build release artifacts (AAB/APK), sign them.
Publish to Google Play, monitor metrics and crashes.
Maintain: updates, analytics, A/B, CI/CD automation.
Components:
Activity: single focused screen controller. Hosts UI. Lifecycle-managed (created→started→resumed→paused→stopped→destroyed).
Fragment: reusable UI piece that lives inside an Activity. Useful for modular UI and navigation.
Service: component for long-running background work (foreground services for visible background tasks).
BroadcastReceiver: listens for system or app-wide broadcasts (power connected, SMS received, custom events).
ContentProvider: exposes structured data so other apps can read/write it (rare for many apps).
Intents: messages used to start components or request actions (implicit vs explicit).
Lifecycle: Android manages component lifecycles — you must design for configuration changes (rotation), background/foreground transitions, process kill and restore.
Permissions: runtime permissions required for sensitive features (location, camera). There’s a permission model and gradations (normal vs dangerous).
Threads & concurrency: UI runs on main thread — long tasks must run off the main thread (background threads, coroutines, executors). Use modern concurrency (Kotlin coroutines or Java concurrency).
Dependency injection: decouples modules (ex: Hilt/Dagger) to improve testability and structure.
Architecture patterns: MVP / MVVM / MVI — MVVM with Jetpack ViewModel + LiveData/Flow is common today — separates UI, domain, data layers.
IDE features: code editor, refactoring, smart completion, linting, profiling tools, layout editor (WYSIWYG), resource manager, AVD (emulator) manager.
Project templates: starter templates (Empty Activity, Navigation Drawer) scaffold common setups.
Gradle integration: the IDE uses Gradle to build. You configure modules, dependencies, build types in Gradle files and Android Studio drives builds.
Run / Debug: debug on emulator or physical device with breakpoints, inspected variables, heap/dump analysis.
Profiler: CPU, Memory, Network profilers find leaks and performance hotspots.
Layout inspector: view runtime UI hierarchy on device.
Resource manager & translations editor: manage localized strings and assets.
Below is a canonical tree for a single-module app (names in parentheses are typical file meanings). I’ll present the tree and then explain each item.
MyApp/ (project root)
├─ .gradle/
├─ .idea/
├─ gradle/
│ └─ wrapper/
├─ build/ (generated build outputs)
├─ gradle.properties
├─ gradlew
├─ gradlew.bat
├─ settings.gradle(.kts)
├─ build.gradle(.kts) (project-level Gradle file)
├─ local.properties (sdk.dir etc — machine-specific)
├─ app/ (module: 'app' — your actual Android app)
│ ├─ build.gradle(.kts) (module-level Gradle)
│ ├─ proguard-rules.pro
│ ├─ src/
│ │ ├─ main/
│ │ │ ├─ AndroidManifest.xml
│ │ │ ├─ java/ or kotlin/ (app source code packages)
│ │ │ │ └─ com/example/myapp/
│ │ │ │ ├─ ui/ (activities, fragments, viewmodels)
│ │ │ │ ├─ data/ (repositories, models, DAOs)
│ │ │ │ ├─ di/ (dependency injection)
│ │ │ │ └─ util/ (helpers)
│ │ │ ├─ res/
│ │ │ │ ├─ layout/ (XML layout files)
│ │ │ │ ├─ drawable/ (images, xml drawables)
│ │ │ │ ├─ mipmap/ (launcher icons)
│ │ │ │ ├─ values/ (strings.xml, colors.xml, styles.xml)
│ │ │ │ ├─ values-<qualifier>/ (locale or size/density specific values)
│ │ │ │ ├─ raw/ (raw resource files)
│ │ │ │ └─ menu/ (menu xml)
│ │ │ └─ assets/ (raw bundled files, fonts sometimes)
│ │ ├─ androidTest/ (instrumented UI tests)
│ │ └─ test/ (unit tests)
│ └─ libs/ (third-party local jar/aars)
├─ README.md
└─ .gitignore
.gradle/: internal Gradle cache for that project (auto-managed).
.idea/: Android Studio project metadata (workspace settings). Keep in VCS selectively.
gradle/: Gradle wrapper files so any machine can run the same Gradle version.
gradlew / gradlew.bat: scripts to run Gradle via the wrapper.
gradle.properties: project-wide Gradle properties (can define JVM args, secrets via environment).
settings.gradle(.kts): tells Gradle which modules are part of the build.
build.gradle (project-level): config shared by modules (repositories, plugin versions, classpath).
local.properties: contains local SDK location — do not commit this to shared VCS.
.gitignore: files not to commit (build outputs, local configs).
README.md: project overview & instructions.
Inside app/ module:
app/build.gradle (module-level): core of module build settings — applicationId, minSdk, targetSdk, versionCode, versionName, dependencies, buildTypes (debug/release), productFlavors (if used), and signing configs. Gradle uses this to produce APK/AAB.
proguard-rules.pro: rules for code shrinking/obfuscation (R8/ProGuard) to keep or remove classes/method names and to control obfuscation.
src/main/AndroidManifest.xml: central manifest that declares app package, app-level metadata, components (Activities, Services), permissions, intent-filters, themes. Build process merges this file with libraries’ manifests.
src/main/java or kotlin: your source code organized by package. Conventionally split into ui/, data/, di/, domain/ etc. The files here compile into dex/classes used by the app.
src/main/res/: app resources (layouts, drawables, strings). Resources are compiled into the app and accessed by resource IDs.
layout/: XML files that declare UI structure. These are inflated into runtime Views.
drawable/: images (PNG, JPG) or XML-defined drawables (shapes, selectors, vectors).
mipmap/: app launcher icons at different densities — kept separate for launcher optimization.
values/strings.xml: user-visible text — used for localization. Never hardcode strings in layouts; use resource strings.
values/colors.xml: color constants used across the app.
values/styles.xml / themes.xml: centralize look-and-feel (colors, fonts, shapes).
values-dimens.xml: standardized spacing and sizing units (dp/sp).
menu/: menu layouts for toolbars, navigation drawers.
raw/: raw binary files (sound, large JSON) bundled as-is.
assets/: arbitrary files accessible via AssetManager at runtime.
src/test/: unit tests that run on the JVM (fast).
src/androidTest/: instrumentation tests that run on device/emulator and can interact with Android framework (Espresso UI tests).
libs/: local libraries (JAR/AAR) not pulled from remote repositories.
Gradle: build automation system. It reads project and module build files and:
resolves dependencies (libraries),
compiles sources,
processes resources,
runs annotation processors (e.g., Dagger/Hilt),
converts Kotlin/Java to bytecode,
runs dexing (convert to Dalvik executable format),
signs and packages APK or AAB.
Build Types:
debug: default for development; debuggable, not obfuscated.
release: optimized, minified/obfuscated, signed with release key.
Product Flavors: produce multiple variants (free/paid, regional). Creates separate build outputs per flavor/build type.
APK vs AAB:
APK: installable package.
AAB (Android App Bundle): preferred for Play; contains all resources and Play serves optimized APKs per device.
Signing: release builds must be signed with a private key (keystore). The keystore must be stored securely; losing it can prevent updates.
R8/ProGuard: code shrinker & obfuscator — removes unused code, shortens names to reduce APK size, and can alter behavior if rules not configured properly.
Multidex: when method count exceeds limit, the app may require multiple dex files; Android plugin handles this with multidex support.
Resource IDs: compile-time generated references (R.java/R.kt) allow code to reference resources.
Qualifiers: resource folders can have qualifiers (e.g., values-fr/ for French, drawable-hdpi/, layout-sw600dp/) so Android selects correct resource depending on device locale, density, screen size, orientation, etc.
Density buckets: provide raster images for mdpi/hdpi/xhdpi/xxhdpi rather than scaling at runtime.
Vector drawables: scalable icons (XML) replacing many raster images.
Strings and localization: place user-visible text in strings.xml per locale. The system picks the right strings file at runtime.
View hierarchy: layouts declare Views (TextView, ImageView, ConstraintLayout, etc.). Android inflates layout XML files into runtime View objects.
Layout inflation: process of converting XML into objects; expensive if used heavily — reuse views (ViewHolder patterns) and keep hierarchies shallow for performance.
dp and sp:
dp (density-independent pixels) for layout sizes and margins.
sp for text sizes (scaled by user font settings).
Themes & styles: centralize colors, typography, and other UI attributes. Material Design provides guidelines and components.
Recycler patterns: for lists, use optimized recycling views (RecyclerView) rather than nesting many views.
In-memory models: simple POJOs/DTOs used by UI.
Local persistence:
SharedPreferences / DataStore: key-value storage for small settings.
Room: SQLite abstraction for structured local storage with DAOs and compile-time checks.
Files / cache dir: for files, images, downloads.
Networking:
Use HTTP client (OkHttp), higher-level mapping (Retrofit) to call REST APIs.
Handle connectivity, timeouts, caching, and error states.
Repository pattern: centralize data access — abstracts whether data is from network or cache/local DB.
Caching: memory and disk caching strategies for performance and offline behavior.
Threading: execute heavy tasks off the main thread. For modern apps, Kotlin coroutines are preferred.
WorkManager: recommended API for deferrable, guaranteed background tasks (suitable for uploads, sync, periodic jobs). It handles constraints (network/connectivity) and survives reboots.
Foreground services: for active background tasks that must continue (media playback, navigation).
JobScheduler / AlarmManager: older scheduling APIs; WorkManager wraps them for compatibility.
Notification channels: required on modern Android to group notifications and let users control their importance.
PendingIntents: allow notifications to trigger app actions.
Deep linking & app links: open specific app screens from URLs or other apps (user flows from web to app).
Runtime permissions: request sensitive permissions at runtime; handle denial and rationales.
Secure data storage: use encrypted preferences or encrypted databases for sensitive data.
Network security: use HTTPS, certificate pinning if needed, and avoid embedding secrets in code.
Obfuscation: R8 reduces reverse engineering, but don't rely solely on it for security.
Least privilege: ask for only the permissions you need and explain why to users.
Unit tests: run on JVM for business logic (fast).
Instrumentation tests: run on device/emulator to test Android APIs (Espresso for UI).
Integration tests: combine modules and real data flows.
End-to-end UI tests: simulate user flows.
Mocking & DI: use dependency injection to swap real services for mocks in tests.
CI integration: set up CI (GitHub Actions, GitLab, Bitrise, Firebase Test Lab) to run tests on PRs and produce build artifacts.
Memory: watch for leaks (use profiler). Avoid holding references to Activities or Contexts in static fields.
Battery: avoid unnecessary wakelocks, background polling; favor push and scheduled background work.
Network: compress payloads, use caching, lazy-load images.
Start-up & cold starts: minimize heavy initialization on app launch (defer to background).
Keystore & signing key: create and securely store a keystore used to sign releases. Keep backups.
Versioning: maintain versionCode (integer) and versionName (string). Increment for each Play release.
Build artifacts:
Prefer AAB for Play (smaller device-optimized APKs).
For sideloading or other stores, use APK.
Play Console:
Create app listing with title, description, screenshots, promo images, privacy policy.
Setup content rating, pricing, distribution countries.
Upload signed AAB, configure release tracks (internal, alpha, beta, production).
Use staged rollouts to limit sudden problems.
App signing by Play: you can opt in to have Play manage your signing key (recommended by Play) or keep your own.
Continuous Integration: build and run tests on pushes/PRs.
Continuous Delivery/Deployment: configure to produce signed release artifacts automatically (on tagged commits).
Store deploy: use Gradle or Play publisher APIs to upload to Play (requires proper credentials).
Crash reporting & monitoring: integrate (Firebase Crashlytics, Sentry) to collect crash and performance data.
Analytics: integrate event-based analytics (Firebase Analytics or other) for usage insights.
Remote config / feature flags: toggle features remotely to test gradually.
A/B testing: measure changes (UI, onboarding, pricing) for conversion improvements.
In-app feedback & crash logs: capture user issues and monitor reports.
Accessibility: ensure content descriptions for images, proper focus order, contrast levels, resizable text (sp/sp), screen reader compatibility.
Internationalization (i18n): externalize strings, supporting right-to-left languages if needed, adapt layouts for longer text.
AndroidX + Jetpack: official libraries for lifecycle, navigation, room, work manager, paging, cameraX, lifecycle-aware components.
ViewModel: stores UI-related data across configuration changes.
LiveData / Flow: observable data streams for UI to react to changes. Flow (Kotlin) is modern.
Navigation component: simplifies in-app navigation, handles back stack, deeplinks.
Room: SQLite wrapper with compile-time query validation.
Paging: efficient loading of paginated data (lists).
CameraX, ML Kit: for camera and ML features.
Compose (UI): Jetpack Compose is the new declarative UI toolkit. If using Compose, project structure and resource handling differ slightly (layouts are Kotlin code instead of XML), but other concepts remain.
Do not perform network I/O on the main thread.
Keep Activity/Fragment logic small; move business logic to ViewModels/UseCases.
Avoid leaking Context; use applicationContext where appropriate.
Test on real devices and multiple API levels & densities.
Use resource qualifiers for multiple screen sizes and densities.
Use vector drawables where possible to reduce APK size.
Keep permissions minimal; explain to the user why you need them.
Always sign and back up your release keystore securely.
Design: sketch screens, user flows; decide storage & network needs.
Scaffold: create project in Android Studio, choose Kotlin (recommended).
Model & Data: define data models, repository interfaces.
UI skeleton: create Activities/Fragments & layouts, wire basic navigation.
Networking & storage: implement API clients and local DB.
Polish: add icons, themes, animations, accessibility.
Testing: write unit and instrumentation tests.
Beta release: internal track or closed beta on Play.
Collect feedback: logs, analytics, fix issues.
Production release: staged rollout.
Maintain: monitor metrics, update, add features.
App icon & adaptive icon created for all densities.
Privacy policy (required for some permissions or data use) URL ready.
Signed release AAB with proper versioning.
Content rating completed.
Target & compile SDK set to recent Android version per Play requirements.
Tested on phones of different hardware and API levels.
Crash reporting & analytics integrated.
Backup of keystore and release credentials stored securely.
AAR: Android Archive — a distributed Android library.
APK: Android Package — installable app bundle.
AAB: Android App Bundle — Play Store package format.
Dex: Dalvik Executable — compiled bytecode for Android runtime.
R.java/R.kt: generated resources class mapping resource names to IDs.
Gradle: build system.
AndroidX: modern support libraries replacing the old support libs.
Jetpack: suite of Android libraries (Navigation, WorkManager, etc.).
If you want, I can:
Provide a tailored checklist for your specific app idea (features, required permissions, target markets).
Lay out a file/folder convention for organizing ui/, domain/, data/ packages for a mid-sized app.
Explain one topic deeper (e.g., App signing, WorkManager, ViewModel lifecycles, Jetpack Compose differences).
Tip: start small with a single Activity + one Fragment, wire data through a repository, and iterate. Use Kotlin + AndroidX + Jetpack libraries for a future-proof stack.