SYSTEMS ARCHITECT & ANDROID PRO

100 Days: Dual-Track Engineering Mastery
[ TARGET: SENIOR ENGINEER / PRODUCT BASED COMPANIES ]
Days Complete 0 / 100
Status ROOKIE
System Build 0%
LVL 01
Days 1 — 10

The Foundations of Compute & OS

Understand voltage turning into logic, and how the Android OS sits on top of a Linux Kernel.
Day
⚙️ Core Systems (1 hr)
🤖 Android Internals (1 hr)
🎯 Proof of Work
✅
01
CS What is computation? Electricity → Voltage → 0/1.
AOSP Android Architecture Stack (Linux Kernel, HAL, ART, Framework).
Draw the Android Architecture diagram from memory.
02
MATH Binary, Decimal, Hex. Converting bases.
OS The Zygote Process. How Android actually boots an app.
Explain Zygote fork() to a rubber duck. Calculate Dec to Hex on paper.
03
MATH Signed vs Unsigned Integers. 1's & 2's Complement.
SEC App Sandbox & UIDs. Why apps can't steal data easily.
Convert -25 to 8-bit binary. Read ADB shell ps output.
04
MATH Floating Point Numbers (IEEE 754 Intuition).
BUILD APK/AAB Structure. What happens when you hit "Build".
Unzip an APK. Inspect classes.dex and resources.arsc.
05
CODE Bitwise Operations (AND, OR, XOR, Shifts).
CORE The 'Context' God Object. Application vs Activity Context.
Write code using bitmasking. Note down when to NOT use Activity Context.
06
THEORY Data representation (Text/ASCII, Image pixels).
CORE Activity Lifecycle (Deep Dive: why onStop vs onDestroy).
App showing lifecycle logs during rotation & home button.
07
LOGIC Boolean Algebra basics (De Morgan's Laws).
CORE Task & BackStack. Launch Modes (SingleTop, SingleTask).
Build a 4-screen app testing different launch mode flags.
08
LOGIC Logic Gates (AND, OR, NAND, XOR). Truth Tables.
CORE SavedInstanceState vs ViewModels (Death & Rebirth).
Simulate process death via adb and restore UI perfectly.
09
LOGIC Half Adders & Full Adders (How CPUs actually add).
RES Resource Qualifiers (sw600dp, night). App Bundles (Play Delivery).
Combine gates on paper to make a Half Adder.
10
BOSS Review: Binary, Adders, Data Representation.
BOSS Review: Architecture, Context, Lifecycle.
Test: Explain how a touch event reaches an Activity in Android.
LVL 02
Days 11 — 20

Algorithms & The UI Pipeline

Train algorithmic thinking. Understand exactly how Android draws pixels to the screen at 60fps.
Day
⚙️ Core Systems (1 hr)
🤖 Android Internals (1 hr)
🎯 Proof of Work
✅
11
DSA Time & Space Complexity Intuition (Big-O).
THREAD Main Thread & Choreographer (The 16ms rule).
Calculate Big-O of nested loops. Explain "Skipped Frames" error.
12
DSA Recursion basics. Call stack visualization.
THREAD Looper, Handler, and MessageQueue mechanics.
Trace recursive Fibonacci. Write custom Handler without Kotlin Coroutines.
13
DSA Divide and Conquer concepts.
UI View Parsing: How LayoutInflater creates objects from XML.
Use Layout Inspector. View the tree depth.
14
DSA Searching: Linear vs Binary Search.
UI The View Lifecycle: onMeasure, onLayout, onDraw passes.
Code Binary Search. Log the View Lifecycle of a custom view.
15
DSA Sorting algorithms (Bubble, Selection - Why they are bad).
UI Custom Views I: Overriding onMeasure properly.
Build a Custom View that forces a specific aspect ratio.
16
DSA Sorting algorithms (Merge Sort - Why it's good).
UI Custom Views II: Canvas API & Paint.
Draw a custom interactive pie chart on a Canvas.
17
DSA Sorting algorithms (Quick Sort).
UI Touch Events Pipeline: dispatchTouchEvent, onIntercept.
Write code to intercept touch events in a parent ViewGroup.
18
DSA Two-pointer technique basics.
PERF UI Overdraw & Layout Hierarchies (ConstraintLayout internals).
Solve 1 Leetcode Two-pointer. Turn on "Show GPU Overdraw" in Dev Options.
19
DSA Sliding Window technique.
PERF RecyclerView Internals: ViewHolders, RecycledViewPool.
Solve 1 Leetcode Sliding Window. Explain why ListView was deprecated.
20
BOSS Algorithm Optimization Test.
BOSS UI Performance Test.
Test: Take a deeply nested LinearLayout and refactor to ConstraintLayout.
LVL 03
Days 21 — 35

C Language & Android Memory Management

Touch the metal. Understand Pointers in C, and how the Android JVM (ART) manages memory and garbage collection.
Day
⚙️ Core Systems (1 hr)
🤖 Android Internals (1 hr)
🎯 Proof of Work
✅
21
C Compilation Process (Preprocess, Compile, Assemble, Link).
MEM Dalvik vs ART (AOT vs JIT compilation).
Compile a C file via terminal. Write short note on ART.
22
C Stack Memory vs Heap Memory concepts.
MEM Android Memory Model (Pages, OOM Killer, LMK).
Draw memory stack frame for a function call.
23
C Pointers & Address-of operators.
MEM Garbage Collection Roots. Mark-and-Sweep algorithm.
Write C code modifying variable via pointer.
24
C Pointer Arithmetic & Array equivalence.
MEM Object References: Strong, Weak, Soft, Phantom.
Write Android code using WeakReference.
25
C Malloc, Calloc, Free (Heap allocation).
MEM Memory Leaks: How they happen in Android (Static contexts).
Create an intentional Memory Leak in an Activity.
26
C Structs and Memory Padding.
TOOL LeakCanary Internals: How it detects leaks (hprof parsing).
Install LeakCanary, find the leak from Day 25.
27
C Memory Leaks in C (Valgrind intro).
MEM Bitmaps: The heaviest objects. Memory calculation.
Calculate byte size of a 1080x1920 ARGB_8888 bitmap.
28
C Segmentation Faults (Why do they happen?).
MEM Bitmap Pooling & Glide/Coil cache mechanisms.
Write C code to intentionally cause a Segfault.
29
C Function Pointers.
TOOL Android Studio Memory Profiler. Heap Dumps.
Take a Heap Dump in AS and analyze shallow vs retained size.
30
C Build a custom String library in C.
NATIVE JNI & NDK Intro. Calling C code from Kotlin.
Setup a basic Android project with C++ native code.
31
C File I/O in C.
STORAGE Scoped Storage & MediaStore API.
Save an image safely in Android 13+.
32
C Macros and Preprocessors.
STORAGE SharedPreferences vs DataStore (Preferences/Proto).
Migrate a SharedPref integer to Preferences DataStore.
33
C Bit Fields.
STORAGE Protobuf Basics for Typed DataStore.
Define a simple .proto file and read it in Android.
34
C Buffer Overflows.
SEC EncryptedSharedPreferences and Keystore System.
Save a fake API key using EncryptedSharedPreferences.
35
BOSS Memory Layout Boss Fight.
BOSS Android Memory & Storage Boss Fight.
Test: Explain exactly why singletons holding context cause OOMs.
LVL 04
Days 36 — 50

Data Structures & App Persistence

Learn why data structures exist (cache issues, lookups) and master Android's Database (Room) & Network libraries.
36
DSA Arrays vs Linked Lists (CPU Cache implications).
DB SQLite Internals & SQLiteOpenHelper.
Implement generic LL in C.
37
DSA Stack implementation & uses.
DB Room DB Basics (Entities, DAOs).
Setup Room. Inspect generated code (Dao_Impl.java).
38
DSA Queue implementation & uses.
DB Room Relationships (1:1, 1:N) without Foreign Keys.
Implement User & Post relationship in Room.
39
DSA Hash Maps (Hash functions, Collisions).
DB Room Migrations under the hood.
Write auto and manual Room migrations.
40
DSA Hash Sets.
ASYNC Kotlin Coroutines Intro (Threads vs Coroutines).
Run 100k coroutines vs 100k threads. Observe output.
41
DSA LRU Cache mechanism.
ASYNC Suspend functions & Continuation Passing Style (CPS).
Decompile suspend func to Java. Look at the state machine.
42
DSA Trees basics (Binary Search Tree).
ASYNC Coroutine Dispatchers (Default vs IO vs Main).
Log thread names while switching Dispatchers.
43
DSA Tree Traversals (Inorder, Preorder, Postorder).
ASYNC Structured Concurrency (Job, SupervisorJob, Scope).
Handle a child coroutine crash without killing the parent.
44
DSA Graphs (Adjacency Matrix vs List).
NET OkHttp Internals: Connection Pool & Dispatcher.
Write an app making simultaneous network calls.
45
DSA BFS (Breadth First Search).
NET OkHttp Interceptors (Application vs Network).
Build an OkHttp Interceptor to inject an Auth Token.
46
DSA DFS (Depth First Search).
NET Retrofit Internals (Dynamic Proxies in Java).
Explain how an Interface becomes executable code in Retrofit.
47
DSA Heaps & Priority Queues.
NET Caching responses using OkHttp Cache.
Implement offline-first network read using cache headers.
48
DSA Tries (Prefix Trees).
NET Serialization/Deserialization (Gson vs Moshi/Kotlinx).
Benchmark Kotlinx Serialization vs Gson.
49
DSA Dynamic Programming basics.
ARCH Repository Pattern. Single Source of Truth.
Combine Room + Retrofit in a cleanly defined Repository.
50
BOSS The Data Architect Test.
BOSS Offline-First Build.
Project: Build a mini app fetching JSON, saving to Room, displaying lists.
LVL 05
Days 51 — 65

Operating Systems & Android IPC/Background

The hardest concepts. Processes, threads, IPC, and how Android manages background work without killing the battery.
51
OS What is an OS? User Space vs Kernel Space.
IPC Binder Mechanism (The heart of Android).
Read docs on Binder. Explain why it's faster than Sockets.
52
OS Processes vs Threads. Context Switching.
IPC Intents under the hood (ActivityManagerService).
Trace the source code of startActivity().
53
OS Process Scheduling Algorithms.
IPC AIDL (Android Interface Definition Language).
Write a basic AIDL to communicate between 2 apps.
54
OS Virtual Memory & Paging.
BG Services (Foreground vs Background).
Implement a Foreground Service playing music.
55
OS Thrashing & Page Faults.
BG Bound Services & Service Connections.
Bind an Activity to a Service to fetch live data.
56
OS Race Conditions & Mutexes.
BG WakeLocks & Doze Mode limitations.
Test app behavior via adb shell dumpsys deviceidle.
57
OS Semaphores & Deadlocks.
BG WorkManager Internals (JobScheduler/AlarmManager).
Schedule a periodic WorkManager task.
58
OS System Calls (open, read, write).
BG WorkManager Constraints & Chaining.
Chain 3 workers (Download -> Compress -> Upload).
59
OS File Systems & Inodes.
COMP Broadcast Receivers (Implicit vs Explicit).
Register dynamic receiver for connectivity changes.
60
OS Disk Scheduling.
COMP Content Providers (Exposing DBs).
Read Contacts using ContentResolver.
61
OS Hardware Interrupts.
PERF App Standby Buckets & Battery Optimization.
Check app standby bucket via adb.
62
OS Linux Permissions & Ownership.
SEC Android Permissions Runtime Model.
Implement modern ActivityResultContracts for permissions.
63
OS `strace` and monitoring tools.
TOOL Using Profiler for Network & CPU.
Profile app startup and find the longest method call.
64
OS Bash scripting basics.
BUILD Custom Gradle tasks.
Write a Gradle task to copy APK to a custom folder.
65
BOSS OS Boss Fight.
BOSS Background App Build.
Project: App that uploads an image in background even if closed.
LVL 06
Days 66 — 75

Networks & Clean App Architecture

Move packets across the internet, and learn how to structure enterprise-grade Android apps (MVVM, DI, StateFlow).
66
NET OSI Model vs TCP/IP.
ARCH MVVM Architecture Deep Dive.
Explain why ViewModels don't hold View references.
67
NET IP Addressing, Subnets, DNS.
ARCH MVI (Model-View-Intent) & UDF.
Draw a diagram of Unidirectional Data Flow.
68
NET TCP vs UDP. 3-Way Handshake.
ASYNC Kotlin Flows (Cold streams).
Transform a List via map/filter in a Flow.
69
NET Sockets & Ports.
ASYNC StateFlow & SharedFlow (Hot streams).
Replace LiveData with StateFlow in a ViewModel.
70
NET HTTP/1.1 vs HTTP/2.
ARCH Dependency Injection concepts.
Write manual constructor injection for a ViewModel.
71
NET HTTPS & SSL/TLS Certificates.
DI Dagger/Hilt Basics (@Inject, @Module).
Setup Hilt in a fresh project and inject a class.
72
NET WebSockets vs Long Polling.
DI Hilt Scopes (@Singleton, @ViewModelScoped).
Inspect the Dagger generated code (DAGs).
73
NET Latency, Bandwidth, CDNs.
ARCH Clean Architecture (Domain vs Data vs UI).
Create separate modules for Domain, Data, UI.
74
TOOL Wireshark packet sniffing.
ARCH UseCases / Interactors.
Extract complex logic into an isolated UseCase.
75
BOSS Build a mini TCP Chat.
BOSS Full Architecture Implementation.
Project: Build Clean Arch + Hilt + StateFlow + Retrofit app.
LVL 07
Days 76 — 85

Software Eng & Jetpack Compose

Professional practices, Git, and mastering the modern declarative UI toolkit for Android.
76
SE Git Internals (Trees, Commits, Hashes).
UI Declarative UI Intro. Compose vs Views.
Build a simple text/button screen in Compose.
77
SE Git Rebase vs Merge.
UI Compose Phases (Composition, Layout, Draw).
Resolve a manual merge conflict.
78
SE SOLID Principles (S & O).
UI State in Compose (remember, mutableStateOf).
Implement state hoisting in Compose.
79
SE SOLID Principles (L, I, D).
UI Modifiers (Order of execution matters).
Build a complex card layout using nested Modifiers.
80
SE Design Patterns (Factory, Builder).
UI LazyColumn & LazyRow (RecyclerView alternative).
Display a list of 1000 items smoothly in Compose.
81
SE Design Patterns (Observer, Strategy).
UI Side Effects (LaunchedEffect, DisposableEffect).
Trigger a snackbar based on ViewModel Flow.
82
SE Unit Testing basics (Arrange, Act, Assert).
PERF Recomposition (Stable vs Unstable classes).
Use Layout Inspector to check composition counts.
83
SE Mocking dependencies.
UI Custom Layouts in Compose.
Write a unit test using MockK.
84
SE CI/CD Concepts (GitHub Actions).
UI Compose Navigation & Deep Links.
Implement Navigation component in Compose.
85
BOSS Review Code Quality.
BOSS Migrate XML to Compose.
Project: Rewrite your previous app's UI purely in Compose.
LVL 08
Days 86 — 100

Production Readiness & System Design

The Final Polish. Learn how to architect huge systems and deploy Android apps like a Senior Engineer.
86
SYS System Design Intro (CAP Theorem).
BUILD Gradle Modularization strategies.
Split app into app, core, feature modules.
87
SYS Load Balancing & Consistent Hashing.
BUILD R8, ProGuard, & Code Obfuscation.
Build release APK. Check obfuscated classes.
88
SYS Database Scaling (Sharding, Replication).
TEST UI Testing with Espresso/Compose Testing.
Write an automated UI test that clicks and verifies text.
89
SYS Caching Strategies (Redis/Memcached).
PERF Macrobenchmark & App Startup profiling.
Setup Macrobenchmark to test Time to Initial Display (TTID).
90
SYS Message Queues (Kafka/RabbitMQ).
PERF Baseline Profiles.
Generate a Baseline Profile to speed up Compose rendering.
91
🚀 INITIATE CAPSTONE PROJECT: "THE FLAGSHIP APP"
92
Requirement Gathering, API Selection, UX Wireframes.
93
Project Setup, Modularization, Dependency Injection Graph setup.
94
Data Layer: Room DAOs, Retrofit Interfaces, Repositories.
95
Domain Layer: UseCases, StateFlow state management.
96
UI Layer: Jetpack Compose screens, Navigation graph.
97
Offline-First logic implementation (Caching, Syncing via WorkManager).
98
Performance Audit: Memory leak check, Overdraw check, Profiling.
99
Unit Tests, Release Build, ProGuard verification.
100
FINAL BOSS: Publish App to Play Store + Write deep dive Tech Article on Architecture.