Kids Learning App: Android Project Structure Explained

The Kids Learning App follows a conventional Android Gradle project layout, with all application source code located under app/src/main/java/com/kidsapp/fiver1/. The package is deliberately flat at the top level for the main activities, with four sub-packages (db/, model/, helper/, layout/, view/, and gameactivities/) handling specialised concerns such as persistence, puzzle rendering, and game modes.

Directory Tree

Kids_learnig_App/
├── app/
│   ├── build.gradle          # App-level Gradle config
│   ├── proguard-rules.pro
│   └── src/main/
│       ├── AndroidManifest.xml
│       ├── java/com/kidsapp/fiver1/
│       │   ├── SplashScreen.java        # Entry point / launcher
│       │   ├── Select_act.java          # Mode picker (Learning vs Games)
│       │   ├── FinalmainScreen.java     # Learning hub
│       │   ├── Animals_question.java    # Animal quiz
│       │   ├── Colours_question_act.java
│       │   ├── FoodActivity.java
│       │   ├── NumbersAct.java
│       │   ├── EmoQuestionsActivity.java
│       │   ├── TravelAct.java
│       │   ├── Vehicals_Act.java
│       │   ├── ScoringPage.java
│       │   ├── Sequencegame.java
│       │   ├── Puzzlemainscreen.java
│       │   ├── Puzzlestart.java
│       │   ├── Show_ImagesMain.java
│       │   ├── AddImge.java
│       │   ├── GameMainAct.java
│       │   ├── GameLoader.java
│       │   ├── AdsClass.java
│       │   ├── db/
│       │   │   ├── MemoryContract.java
│       │   │   ├── MemoryDbHelper.java
│       │   │   └── MemoriesAdapter.java
│       │   ├── model/
│       │   │   └── Memory.java
│       │   ├── helper/
│       │   │   ├── DataHelper.java
│       │   │   ├── Block.java
│       │   │   └── BitmapUtil.java
│       │   ├── layout/
│       │   │   └── PuzzleLayout.java
│       │   ├── view/
│       │   │   └── PuzzleView.java
│       │   └── gameactivities/
│       │       ├── Action.java
│       │       ├── Cards.java
│       │       ├── Classic.java
│       │       ├── Racing.java
│       │       └── Contact.java
│       └── res/
│           ├── drawable/   # Quiz images (b0-b9 animals, c0-c9 food, etc.)
│           ├── layout/     # XML layouts
│           ├── raw/        # background_music.mp3
│           └── anim/       # zoom_in, zoom1-5 animations
└── build.gradle             # Project-level Gradle

Key Packages

db/ — SQLite persistence layer for the photo gallery

The db/ package contains all database infrastructure for the Memory Gallery feature:

MemoryContract.java — Defines the SQLite table schema as static constants (table name, column names). Acts as the single source of truth for column identifiers used across the package.
MemoryDbHelper.java — Extends SQLiteOpenHelper. Handles onCreate and onUpgrade, creating and migrating the memories table that stores Base64-encoded image strings and metadata.
MemoriesAdapter.java — A RecyclerView.Adapter that binds Memory model objects to gallery item views in Show_ImagesMain. Handles decoding Base64 strings back to Bitmap for display.

model/ — Memory data model

The model/ package contains a single class:

Memory.java — A plain Java object (POJO) representing one gallery entry. It holds the image encoded as a Base64 string (images are resized to 250 × 250 px via BitmapUtil before encoding) along with any associated metadata. This model is serialised to/from the SQLite database through MemoryDbHelper and surfaced in the UI by MemoriesAdapter.

helper/ — Puzzle tile logic and bitmap utilities

The helper/ package provides shared utilities used by the puzzle feature:

DataHelper.java — Manages the puzzle tile data structure. Implements the core tile-swap algorithm: tiles are represented as an ordered list of Block objects; DataHelper handles shuffling (with solvability checking) and validates move legality before committing a swap.
Block.java — A lightweight value object representing a single puzzle tile. Stores the tile’s current position index and its correct (solved) position, allowing DataHelper to detect when the puzzle is complete.
BitmapUtil.java — Utility methods for bitmap manipulation: resizing images to the target dimensions (250 × 250 px for gallery storage) and converting between Bitmap and Base64 String for SQLite persistence.

layout/ and view/ — Custom puzzle rendering

These two packages together implement the custom puzzle UI:

PuzzleLayout.java (layout/) — A custom ViewGroup that arranges PuzzleView children in a grid. It overrides onMeasure and onLayout to size and position each tile without relying on standard layout managers, giving precise control over tile boundaries.
PuzzleView.java (view/) — A custom View that renders a single puzzle tile. It draws the appropriate cropped region of the source bitmap using Canvas and handles touch events, forwarding valid swipe gestures to DataHelper for processing.

gameactivities/ — Game hub activity classes

The gameactivities/ package contains the Activity subclasses loaded by GameLoader when a child selects a game category in GameMainAct:

Action.java — Hosts the Action-category WebView, loading an action game URL into a full-screen WebView with JavaScript enabled.
Cards.java — Hosts card-based games (e.g., memory card flip) in a dedicated WebView activity.
Classic.java — Hosts classic mini-games such as simple platformers or arcade titles via WebView.
Racing.java — Hosts racing games in a WebView with landscape orientation locked.
Contact.java — A lightweight screen providing developer contact information and app version details, accessible from within the game hub.

Drawable Naming Conventions

All quiz and answer images in res/drawable/ follow a strict prefix-and-index naming scheme. Understanding this convention is essential when adding new quiz content or debugging missing image errors.

Prefix	Content
`b0` – `b9`	Animal question images
`a0` – `a24`	Animal answer images
`c0` – `c9`	Food question/answer images
`d0` – `d19`	Answer distractor images
`e0` – `e9`	Emotion question images
`h0` – `h22`	Colours & shapes images
`m0` – `m9`	Number answer images
`n0` – `n9`	Number question images
`o0` – `o9`	Object answer images
`p0` – `p2`	Person images
`q0` – `q9`	Things / vehicles question images
`s0` – `s9`	Transport answer images
`t0` – `t9`	Transport question images
`w0` – `w16`	Wildlife / world answer images

Activity Flow

The diagram below summarises the primary navigation paths through the app:

SplashScreen (launcher)
    └── Select_act (mode picker)
            ├── FinalmainScreen (learning hub)
            │       ├── Animals_question
            │       ├── Colours_question_act
            │       ├── FoodActivity
            │       ├── NumbersAct
            │       ├── EmoQuestionsActivity
            │       ├── TravelAct
            │       ├── Vehicals_Act
            │       │       └── ScoringPage (shared results screen)
            │       └── Sequencegame → ScoringPage
            ├── Puzzlemainscreen → Puzzlestart
            ├── Show_ImagesMain ↔ AddImge
            └── GameMainAct → GameLoader
                    └── gameactivities/ (Action, Cards, Classic, Racing)

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Kids Learning App: Android Project Structure Explained

Directory Tree

Key Packages

Drawable Naming Conventions

Activity Flow

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Documentation Index

​Directory Tree

​Key Packages

​Drawable Naming Conventions

​Activity Flow

Build docs developers (and LLMs) love

Directory Tree

Key Packages

Drawable Naming Conventions

Activity Flow