BMI-calculator/README.md

🏋️ BMI Calculator

Modern Android aplikasi untuk menghitung Body Mass Index (BMI) dengan antarmuka yang clean dan intuitif menggunakan Jetpack Compose dan Material Design 3.

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📋 Daftar Isi

• Fitur
• Teknologi
• Arsitektur
• Instalasi
• Cara Menggunakan
• Testing
• Struktur Project
• Kategori BMI
• Formula Perhitungan
• Kontribusi
• Lisensi
• Kontak

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✨ Fitur

🎯 Core Features

• ✅ Perhitungan BMI Akurat - Formula standar WHO untuk Metric dan Imperial
• ✅ Dual Unit System - Support Metric (kg, cm) dan Imperial (lb, in)
• ✅ Kategori BMI - Underweight, Normal, Overweight, Obese dengan color coding
• ✅ Healthy Weight Range - Menampilkan rentang berat ideal berdasarkan tinggi
• ✅ Input Validation - Validasi real-time untuk input yang valid
• ✅ Error Handling - Error messages yang jelas dan helpful

🎨 UI/UX Features

• ✅ Modern UI - Jetpack Compose dengan Material Design 3
• ✅ Smooth Animations - Spring animations untuk hasil BMI
• ✅ Clean Design - Minimalist interface dengan visual hierarchy yang jelas
• ✅ Material Icons - Icon yang meaningful untuk setiap elemen
• ✅ Welcome Screen - Onboarding screen dengan ilustrasi
• ✅ Responsive Layout - Adaptive untuk berbagai ukuran layar
• ✅ Color-coded Results - Visual feedback berdasarkan kategori BMI

🔧 Technical Features

• ✅ Jetpack Compose - 100% Compose UI (no XML layouts)
• ✅ Material Design 3 - Latest design system
• ✅ Type Safety - Kotlin with strong typing
• ✅ Unit Tested - 93+ test cases dengan coverage >90%
• ✅ Edge-to-Edge - Modern Android edge-to-edge support
• ✅ No Dependencies - Pure Android SDK (no third-party libraries)

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🛠 Teknologi

Core Technologies

Technology	Version	Purpose
Kotlin	1.9+	Programming language
Jetpack Compose	2025.11	Modern UI toolkit
Material Design 3	Latest	Design system
Android SDK	Min 24, Target 36	Android platform
JUnit 4	4.13.2	Unit testing

Key Libraries

// Compose BOM
implementation(platform("androidx.compose:compose-bom:2025.11.00"))

// Compose Core
implementation("androidx.compose.ui:ui")
implementation("androidx.compose.material3:material3")
implementation("androidx.compose.material:material-icons-extended")

// Activity Compose
implementation("androidx.activity:activity-compose:1.11.0")

// Core
implementation("androidx.core:core-ktx:1.17.0")
implementation("androidx.lifecycle:lifecycle-runtime-ktx:2.9.4")

Development Tools

• Gradle 8.x - Build system
• Android Studio Koala+ - IDE
• Git - Version control

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🏗 Arsitektur

Project Structure

app/
├── src/
│   ├── main/
│   │   ├── java/com/example/tiptime/
│   │   │   ├── MainActivity.kt              # Main entry point
│   │   │   ├── WelcomeActivity.kt           # Welcome screen
│   │   │   ├── model/
│   │   │   │   ├── BmiData.kt               # BMI data class
│   │   │   │   ├── BmiCategory.kt           # BMI categories enum
│   │   │   │   └── UnitSystem.kt            # Metric/Imperial enum
│   │   │   ├── ui/
│   │   │   │   ├── BmiCalculatorScreen.kt   # Main calculator UI
│   │   │   │   └── theme/
│   │   │   │       ├── Color.kt             # Color definitions
│   │   │   │       ├── Theme.kt             # App theme
│   │   │   │       └── Type.kt              # Typography
│   │   │   └── utils/
│   │   │       └── BmiCalculator.kt         # BMI calculation logic
│   │   └── res/
│   │       ├── drawable/
│   │       │   └── image_bmi.png            # Welcome illustration
│   │       └── values/
│   │           └── strings.xml              # String resources
│   └── test/
│       └── java/com/example/tiptime/
│           ├── utils/
│           │   └── BmiCalculatorTest.kt     # 43 unit tests
│           └── model/
│               ├── BmiCategoryTest.kt       # 30+ unit tests
│               ├── BmiDataTest.kt           # 10 unit tests
│               └── UnitSystemTest.kt        # 10 unit tests

Design Pattern

• MVVM-like Structure - Separation of UI and business logic
• Single Activity - Modern Android navigation
• Stateless Composables - Unidirectional data flow
• Utility Classes - Pure functions for calculations
• Material Design - Following Material 3 guidelines

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💿 Instalasi

Prerequisites

• Android Studio Koala (2024.1.1) atau lebih baru
• JDK 17 atau lebih baru
• Android SDK API 24+ (Android 7.0)
• Git untuk clone repository

Clone & Build

# 1. Clone repository
git clone https://git.lab.ubharajaya.ac.id/202310715083-RAKHA-ADI-SAPUTRO/BMI-calculator.git
cd bmi-calculator

# 2. Open di Android Studio
# File → Open → Pilih folder project

# 3. Sync Gradle
# Android Studio akan otomatis sync dependencies

# 4. Build project
./gradlew build

# Windows:
gradlew.bat build

# 5. Run aplikasi
# Pilih device/emulator → Click Run (▶️)

Install APK

# Build debug APK
./gradlew assembleDebug

# APK tersedia di:
# app/build/outputs/apk/debug/app-debug.apk

# Install ke device
./gradlew installDebug

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📖 Cara Menggunakan

Langkah Penggunaan

1. Buka Aplikasi

   • Lihat welcome screen
   • Tap "Get Started"

2. Pilih Unit System

   • Metric: kg & cm
   • Imperial: lb & in

3. Input Data

   • Masukkan Weight (berat badan)
   • Masukkan Height (tinggi badan)

4. Hitung BMI

   • Tap tombol "Calculate BMI"
   • Hasil akan muncul dengan animasi

5. Lihat Hasil

   • BMI Value - Nilai BMI Anda
   • Category - Underweight/Normal/Overweight/Obese
   • Healthy Range - Rentang berat ideal Anda
   • BMI Categories - Info kategori BMI

Input Validation

System	Weight Range	Height Range
Metric	1-500 kg	50-300 cm
Imperial	2-1100 lb	20-120 in

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🧪 Testing

Unit Tests

Project ini memiliki 93+ unit tests dengan coverage >90%.

Jalankan Test

# Command Line
./gradlew test

# Windows
gradlew.bat test

# Lihat HTML Report
# app/build/reports/tests/test/index.html

Test Coverage

File	Tests	Coverage
BmiCalculatorTest.kt	43	Perhitungan, validasi, boundary
BmiCategoryTest.kt	30+	Kategori, warna, display
BmiDataTest.kt	10	Data class, equality
UnitSystemTest.kt	10	Enum values

Contoh Test Cases

// Test perhitungan BMI
@Test
fun calculateBmi_metric_normal_returnsCorrectBmi() {
    // 70 kg, 175 cm -> BMI = 22.86 (Normal)
    val result = BmiCalculator.calculateBmi(70.0, 175.0, UnitSystem.METRIC)
    assertEquals(22.86, result.bmi, 0.01)
    assertEquals(BmiCategory.NORMAL, result.category)
}

// Test boundary values
@Test
fun fromBmi_exactNormalLowerBoundary_returnsNormal() {
    // BMI 18.5 (tepat batas bawah normal)
    assertEquals(BmiCategory.NORMAL, BmiCategory.fromBmi(18.5))
}

Untuk panduan lengkap, baca: TESTING_GUIDE.md

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📊 Kategori BMI

Berdasarkan standar WHO (World Health Organization):

Kategori	BMI Range	Color	Status
Underweight	< 18.5	🔵 Blue	Berat badan kurang
Normal	18.5 - 24.9	🟢 Green	Berat badan ideal
Overweight	25.0 - 29.9	🟠 Orange	Kelebihan berat badan
Obese	≥ 30.0	🔴 Red	Obesitas

Visual Color Coding

val UnderweightColor = Color(0xFF3B82F6)  // Blue
val NormalColor = Color(0xFF10B981)       // Green
val OverweightColor = Color(0xFFF59E0B)   // Orange
val ObeseColor = Color(0xFFEF4444)        // Red

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🔬 Formula Perhitungan

Metric System (kg, cm)

BMI = weight (kg) / (height (m))²

Contoh:

• Weight: 70 kg
• Height: 175 cm = 1.75 m
• BMI = 70 / (1.75)² = 22.86

Imperial System (lb, in)

BMI = (weight (lb) / (height (in))²) × 703

Contoh:

• Weight: 150 lb
• Height: 67 in
• BMI = (150 / (67)²) × 703 = 23.49

Healthy Weight Range

// Untuk BMI 18.5 - 24.9
minWeight = 18.5 × (height)²
maxWeight = 24.9 × (height)²

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🎨 Theme & Colors

Color Palette

// Primary Colors
val PrimaryBlue = Color(0xFF2563EB)
val PrimaryBlueDark = Color(0xFF1E40AF)
val BackgroundLight = Color(0xFFF8FAFC)

// Text Colors
val TextPrimary = Color(0xFF1E293B)
val TextSecondary = Color(0xFF64748B)

// BMI Category Colors
val UnderweightColor = Color(0xFF3B82F6)  // Blue
val NormalColor = Color(0xFF10B981)       // Green
val OverweightColor = Color(0xFFF59E0B)   // Orange
val ObeseColor = Color(0xFFEF4444)        // Red

Material Icons

• FitnessCenter - App header icon
• MonitorWeight - Weight input icon
• Height - Height input icon
• Calculate - Calculate button icon

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🔧 Configuration

Build Configuration

android {
    compileSdk = 36
    
    defaultConfig {
        applicationId = "com.example.tiptime"
        minSdk = 24
        targetSdk = 36
        versionCode = 1
        versionName = "1.0"
    }
    
    compileOptions {
        sourceCompatibility = JavaVersion.VERSION_17
        targetCompatibility = JavaVersion.VERSION_17
    }
    
    kotlinOptions {
        jvmTarget = "17"
    }
}

Gradle Version

• Gradle: 8.9
• AGP: 8.7.3
• Kotlin: 2.0.21

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🤝 Kontribusi

Kontribusi sangat diterima! Berikut cara berkontribusi:

Steps

1. Fork repository ini
2. Create feature branch (git checkout -b feature/AmazingFeature)
3. Commit changes (git commit -m 'Add some AmazingFeature')
4. Push to branch (git push origin feature/AmazingFeature)
5. Open Pull Request

Guidelines

• ✅ Ikuti Kotlin coding conventions
• ✅ Tulis unit tests untuk fitur baru
• ✅ Update dokumentasi jika perlu
• ✅ Pastikan semua tests pass
• ✅ Gunakan commit messages yang jelas

Bug Reports

Jika menemukan bug, silakan buat issue dengan detail:

• Deskripsi bug
• Steps to reproduce
• Expected vs actual behavior
• Screenshots (jika ada)
• Device & Android version

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📝 Changelog

Version 1.0.0 (November 2025)

Initial Release

✨ Features:

• BMI calculation (Metric & Imperial)
• Welcome screen dengan ilustrasi
• Modern Material Design 3 UI
• Input validation
• Healthy weight range
• Animated results
• BMI categories info card

🧪 Tests:

• 93+ unit tests

• 90% code coverage

• Boundary value testing
• Edge case handling

🎨 UI/UX:

• Clean, modern interface
• Color-coded categories
• Material icons
• Smooth animations
• Responsive layout

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👥 Authors

[NPM: 202310715083]
[Nama: Rakha Adi Saputro]

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📞 Kontak

• Email: rakhaadi24@gmail.com
• GitHub: https://github.com/Rakhasptro follow guys

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🙏 Acknowledgments

• Android Team - Jetpack Compose & Material Design 3
• WHO - BMI classification standards
• Material Design - Design guidelines & icons
• Kotlin Team - Amazing programming language
• Open Source Community - Inspiration & support

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📚 Resources

Documentation

• Jetpack Compose
• Material Design 3
• Kotlin Language

Related Projects

• Android Compose Samples
• Material 3 Catalog

Learning Resources

• Android Basics with Compose
• Kotlin Bootcamp

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⭐ Star History

Jika project ini membantu Anda, berikan ⭐ di GitHub!

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