Panduan Android

// panduan_android.kt
// Tour singkat Panduan Android Kotlin:
// https://developer.android.com/kotlin
//
// Mendemokan konsep yang sering muncul di pengembangan Android dengan Kotlin
// (tanpa Android SDK — dijalankan di JVM biasa).

// 1. Activity Lifecycle — simulasi state mesin status
enum class ActivityState {
    CREATED, STARTED, RESUMED, PAUSED, STOPPED, DESTROYED
}

class ActivitySimulasi {
    var state: ActivityState = ActivityState.CREATED
        private set

    fun onCreate()    { state = ActivityState.CREATED;  println("  onCreate() -> $state") }
    fun onStart()     { state = ActivityState.STARTED;  println("  onStart() -> $state") }
    fun onResume()    { state = ActivityState.RESUMED; println("  onResume() -> $state") }
    fun onPause()     { state = ActivityState.PAUSED;  println("  onPause() -> $state") }
    fun onStop()      { state = ActivityState.STOPPED; println("  onStop() -> $state") }
    fun onDestroy()   { state = ActivityState.DESTROYED; println("  onDestroy() -> $state") }
}

// 2. ViewModel — menyimpan state UI yang selamat dari rotasi
class PenggunaViewModel {
    var nama: String = ""
        private set
    var skor: Int = 0
        private set

    fun setNama(n: String) { nama = n }
    fun tambahSkor(n: Int = 1) { skor += n }
}

// 3. LiveData/StateFlow simulasi — observable state
class CounterMutable {
    private var nilai: Int = 0
    private val observers = mutableListOf<(Int) -> Unit>()

    fun observe(block: (Int) -> Unit) {
        observers.add(block)
    }

    fun setNilai(n: Int) {
        nilai = n
        observers.forEach { it(nilai) }
    }
}

// 4. Intent (pindah activity) — simulasi
data class Intent(val action: String, val extras: Map<String, String> = emptyMap())

class NavigasiActivity {
    private val stack = mutableListOf<String>("MainActivity")

    fun startActivity(intent: Intent) {
        stack.add(intent.action)
        println("  Navigasi ke ${intent.action}, extras=${intent.extras}")
    }

    fun back(): String? {
        if (stack.size > 1) {
            stack.removeAt(stack.lastIndex)
            println("  Back ke ${stack.last()}")
        }
        return stack.lastOrNull()
    }
}

fun main() {
    println("=== Panduan Android dengan Kotlin ===")
    println("Sumber: https://developer.android.com/kotlin")
    println()

    println("--- 1. Activity Lifecycle ---")
    val act = ActivitySimulasi()
    act.onCreate()
    act.onStart()
    act.onResume()
    act.onPause()
    act.onStop()
    act.onDestroy()

    println()
    println("--- 2. ViewModel state ---")
    val vm = PenggunaViewModel()
    vm.setNama("Budi")
    vm.tambahSkor(5)
    vm.tambahSkor(3)
    println("  ViewModel: nama=${vm.nama}, skor=${vm.skor}")
    println("  (State selamat dari rotasi layar)")

    println()
    println("--- 3. Observable state (mirip StateFlow) ---")
    val counter = CounterMutable()
    counter.observe { println("  Observer 1: nilai = $it") }
    counter.observe { println("  Observer 2: nilai = $it (x2 = ${it * 2})") }
    counter.setNilai(10)
    counter.setNilai(25)

    println()
    println("--- 4. Intent dan navigasi ---")
    val nav = NavigasiActivity()
    nav.startActivity(Intent("DetailActivity", mapOf("id" to "42")))
    nav.startActivity(Intent("EditActivity", mapOf("id" to "42", "mode" to "edit")))
    nav.back()
    nav.back()

    println()
    println("--- 5. Stack Android modern ---")
    val stack = listOf(
        "Jetpack Compose   -> UI deklaratif (replace XML layout)",
        "ViewModel         -> state yang selamat dari rotasi",
        "Navigation Compose -> type-safe navigation",
        "Room              -> ORM SQLite dengan @Dao",
        "Hilt              -> dependency injection",
        "Retrofit          -> HTTP client dengan @GET, @POST",
        "Coroutines        -> async programming (Dispatchers.Main)",
        "DataStore         -> pengganti SharedPreferences (async)"
    )
    stack.forEach { println("  $it") }

    println()
    println("--- 6. Resource Android ---")
    val res = listOf(
        "res/layout/         -> XML layout (legacy)",
        "res/values/strings.xml -> string terjemahan",
        "res/drawable/       -> gambar (PNG, Vector)",
        "res/mipmap/         -> app icon",
        "AndroidManifest.xml -> deklarasi komponen app"
    )
    res.forEach { println("  $it") }

    println()
    println("--- 7. Cara belajar Android Kotlin ---")
    val cara = listOf(
        "1. Install Android Studio (bundled Kotlin + emulator)",
        "2. Buat project 'Empty Compose Activity'",
        "3. Pelajari Jetpack Compose (UI modern)",
        "4. Tambahkan ViewModel + Room untuk state persistence",
        "5. Tambahkan Retrofit untuk network call",
        "6. Deploy ke device fisik via USB debugging"
    )
    cara.forEach { println("  $it") }
}

=== Panduan Android dengan Kotlin ===
Sumber: https://developer.android.com/kotlin

--- 1. Activity Lifecycle ---
  onCreate() -> CREATED
  onStart() -> STARTED
  onResume() -> RESUMED
  onPause() -> PAUSED
  onStop() -> STOPPED
  onDestroy() -> DESTROYED

--- 2. ViewModel state ---
  ViewModel: nama=Budi, skor=8
  (State selamat dari rotasi layar)

--- 3. Observable state (mirip StateFlow) ---
  Observer 1: nilai = 10
  Observer 2: nilai = 10 (x2 = 20)
  Observer 1: nilai = 25
  Observer 2: nilai = 25 (x2 = 50)

--- 4. Intent dan navigasi ---
  Navigasi ke DetailActivity, extras={id=42}
  Navigasi ke EditActivity, extras={id=42, mode=edit}
  Back ke DetailActivity
  Back ke MainActivity

--- 5. Stack Android modern ---
  Jetpack Compose   -> UI deklaratif (replace XML layout)
  ViewModel         -> state yang selamat dari rotasi
  Navigation Compose -> type-safe navigation
  Room              -> ORM SQLite dengan @Dao
  Hilt              -> dependency injection
  Retrofit          -> HTTP client dengan @GET, @POST
  Coroutines        -> async programming (Dispatchers.Main)
  DataStore         -> pengganti SharedPreferences (async)

--- 6. Resource Android ---
  res/layout/         -> XML layout (legacy)
  res/values/strings.xml -> string terjemahan
  res/drawable/       -> gambar (PNG, Vector)
  res/mipmap/         -> app icon
  AndroidManifest.xml -> deklarasi komponen app

--- 7. Cara belajar Android Kotlin ---
  1. Install Android Studio (bundled Kotlin + emulator)
  2. Buat project 'Empty Compose Activity'
  3. Pelajari Jetpack Compose (UI modern)
  4. Tambahkan ViewModel + Room untuk state persistence
  5. Tambahkan Retrofit untuk network call
  6. Deploy ke device fisik via USB debugging