Use Koin for dependency injection

Author: MarkNjunge

app/build.gradle

@@ -62,6 +62,7 @@ dependencies {
     implementation deps.crashlytics
     debugImplementation deps.leakCanary
     releaseImplementation deps.leakCanaryNoOp
+    implementation deps.koin
 
     // Test libraries
     testImplementation deps.junit

app/src/main/java/com/marknkamau/justjava/JustJavaApp.kt

@@ -7,8 +7,6 @@ import androidx.localbroadcastmanager.content.LocalBroadcastManager
 import com.marknjunge.core.auth.AuthService
 import com.marknjunge.core.auth.AuthServiceImpl
 import com.marknkamau.justjava.data.local.CartDatabase
-import com.marknkamau.justjava.data.local.PreferencesRepository
-import com.marknkamau.justjava.data.local.PreferencesRepositoryImpl
 import com.marknkamau.justjava.utils.NotificationHelper
 import timber.log.Timber
 import io.fabric.sdk.android.Fabric
@@ -18,16 +16,15 @@ import com.marknjunge.core.data.firebase.ClientDatabaseService
 import com.marknjunge.core.data.firebase.WriteListener
 import com.marknjunge.core.mpesa.MpesaInteractor
 import com.marknjunge.core.mpesa.MpesaInteractorImpl
+import com.marknkamau.justjava.di.appModule
 import com.squareup.leakcanary.LeakCanary
+import org.koin.android.ext.android.inject
+import org.koin.android.ext.koin.androidContext
+import org.koin.core.context.startKoin
 
 class JustJavaApp : Application() {
-    lateinit var preferencesRepo: PreferencesRepository
-    lateinit var authService: AuthService
-    lateinit var databaseService: ClientDatabaseService
-    lateinit var cartDatabase: CartDatabase
-    lateinit var notificationHelper: NotificationHelper
-    lateinit var mpesaInteractor: MpesaInteractor
-    lateinit var broadcastManager: androidx.localbroadcastmanager.content.LocalBroadcastManager
+    private val authService: AuthService by inject()
+    private val databaseService: ClientDatabaseService by inject()
 
     override fun onCreate() {
         super.onCreate()
@@ -40,23 +37,17 @@ class JustJavaApp : Application() {
                     return "Timber ${super.createStackElementTag(element)}.${element.methodName}"
                 }
             })
-        }else{
+        } else {
             val fabric = Fabric.Builder(this)
                     .kits(Crashlytics())
                     .build()
             Fabric.with(fabric)
         }
 
-        preferencesRepo = PreferencesRepositoryImpl(PreferenceManager.getDefaultSharedPreferences(this))
-        authService = AuthServiceImpl()
-        databaseService = ClientDatabaseImpl()
-        mpesaInteractor = MpesaInteractorImpl()
-
-        cartDatabase = Room.databaseBuilder(this, CartDatabase::class.java, "cart-db").build()
-
-        notificationHelper = NotificationHelper(this)
-
-        broadcastManager = androidx.localbroadcastmanager.content.LocalBroadcastManager.getInstance(this)
+        startKoin {
+            androidContext(this@JustJavaApp)
+            modules(appModule)
+        }
 
         if (authService.isSignedIn()) {
             val user = authService.getCurrentUser()

app/src/main/java/com/marknkamau/justjava/data/network/MyFirebaseMessagingService.kt

@@ -1,10 +1,16 @@
 package com.marknkamau.justjava.data.network
 
 import android.content.Intent
+import androidx.localbroadcastmanager.content.LocalBroadcastManager
 import com.google.firebase.messaging.FirebaseMessagingService
 import com.google.firebase.messaging.RemoteMessage
+import com.marknjunge.core.auth.AuthService
+import com.marknjunge.core.data.firebase.ClientDatabaseService
 import com.marknjunge.core.data.firebase.WriteListener
 import com.marknkamau.justjava.JustJavaApp
+import com.marknkamau.justjava.utils.NotificationHelper
+import org.koin.android.ext.android.inject
+import org.koin.core.KoinComponent
 import timber.log.Timber
 
 /**
@@ -13,11 +19,11 @@ import timber.log.Timber
  * https://github.com/MarkNjunge
  */
 
-class MyFirebaseMessagingService : FirebaseMessagingService() {
-    private val notificationHelper by lazy { (application as JustJavaApp).notificationHelper }
-    private val broadcastManager by lazy { (application as JustJavaApp).broadcastManager }
-    private val authService by lazy { (application as JustJavaApp).authService }
-    private val databaseService by lazy { (application as JustJavaApp).databaseService }
+class MyFirebaseMessagingService : FirebaseMessagingService(), KoinComponent {
+    private val notificationHelper: NotificationHelper by inject()
+    private val broadcastManager by lazy { LocalBroadcastManager.getInstance(this) }
+    private val authService: AuthService by inject()
+    private val databaseService: ClientDatabaseService by inject()
 
     companion object {
         const val MPESA_ORDER_PAID_ACTION = "mpesa"

app/src/main/java/com/marknkamau/justjava/di/Modules.kt

@@ -0,0 +1,26 @@
+package com.marknkamau.justjava.di
+
+import android.preference.PreferenceManager
+import androidx.room.Room
+import com.marknjunge.core.auth.AuthService
+import com.marknjunge.core.auth.AuthServiceImpl
+import com.marknjunge.core.data.firebase.ClientDatabaseImpl
+import com.marknjunge.core.data.firebase.ClientDatabaseService
+import com.marknjunge.core.mpesa.MpesaInteractor
+import com.marknjunge.core.mpesa.MpesaInteractorImpl
+import com.marknkamau.justjava.data.local.CartDatabase
+import com.marknkamau.justjava.data.local.PreferencesRepository
+import com.marknkamau.justjava.data.local.PreferencesRepositoryImpl
+import com.marknkamau.justjava.utils.NotificationHelper
+import org.koin.android.ext.koin.androidContext
+import org.koin.dsl.module
+
+val appModule = module {
+    single<PreferencesRepository> { PreferencesRepositoryImpl(PreferenceManager.getDefaultSharedPreferences(androidContext())) }
+    single<AuthService> { AuthServiceImpl() }
+    single<ClientDatabaseService> { ClientDatabaseImpl() }
+    single { Room.databaseBuilder(androidContext(), CartDatabase::class.java, "cart-db").build() }
+    single { get<CartDatabase>().cartDao() }
+    single { NotificationHelper(androidContext()) }
+    single<MpesaInteractor> { MpesaInteractorImpl() }
+}

app/src/main/java/com/marknkamau/justjava/ui/BaseActivity.kt

@@ -6,18 +6,21 @@ import androidx.appcompat.app.AppCompatActivity
 import android.view.Menu
 import android.view.MenuItem
 import android.widget.Toast
+import com.marknjunge.core.auth.AuthService
 import com.marknkamau.justjava.JustJavaApp
 import com.marknkamau.justjava.R
+import com.marknkamau.justjava.data.local.PreferencesRepository
 import com.marknkamau.justjava.ui.about.AboutActivity
 import com.marknkamau.justjava.ui.cart.CartActivity
 import com.marknkamau.justjava.ui.checkout.CheckoutActivity
 import com.marknkamau.justjava.ui.login.LogInActivity
 import com.marknkamau.justjava.ui.profile.ProfileActivity
+import org.koin.android.ext.android.inject
 
 abstract class BaseActivity : AppCompatActivity() {
 
-    private val authService by lazy { (application as JustJavaApp).authService }
-    private val preferencesRepository by lazy { (application as JustJavaApp).preferencesRepo }
+    private val authService: AuthService by inject()
+    private val preferencesRepository: PreferencesRepository by inject()
 
     override fun onCreateOptionsMenu(menu: Menu): Boolean {
         val inflater = menuInflater

app/src/main/java/com/marknkamau/justjava/ui/cart/CartActivity.kt

@@ -10,15 +10,17 @@ import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
 import com.marknkamau.justjava.JustJavaApp
 import com.marknkamau.justjava.R
+import com.marknkamau.justjava.data.local.CartDao
 import com.marknkamau.justjava.data.models.CartItem
 import com.marknkamau.justjava.ui.BaseActivity
 import com.marknkamau.justjava.ui.checkout.CheckoutActivity
 import kotlinx.android.synthetic.main.activity_cart.*
+import org.koin.android.ext.android.inject
 
 class CartActivity : BaseActivity(), CartView {
     private lateinit var presenter: CartPresenter
     private lateinit var adapter: CartAdapter
-    private val cartDao by lazy { (application as JustJavaApp).cartDatabase.cartDao() }
+    private val cartDao: CartDao by inject()
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)

app/src/main/java/com/marknkamau/justjava/ui/checkout/CheckoutActivity.kt

@@ -9,16 +9,21 @@ import android.text.TextUtils
 import android.view.View
 import android.widget.RadioButton
 import android.widget.Toast
+import com.marknjunge.core.auth.AuthService
+import com.marknjunge.core.data.firebase.ClientDatabaseService
 import com.marknkamau.justjava.JustJavaApp
 import com.marknkamau.justjava.R
 import com.marknjunge.core.model.Order
 import com.marknjunge.core.model.UserDetails
+import com.marknkamau.justjava.data.local.CartDao
+import com.marknkamau.justjava.data.local.PreferencesRepository
 import com.marknkamau.justjava.ui.BaseActivity
 import com.marknkamau.justjava.ui.login.LogInActivity
 import com.marknkamau.justjava.ui.main.MainActivity
 import com.marknkamau.justjava.ui.previousOrder.PreviousOrderActivity
 import com.marknkamau.justjava.utils.trimmedText
 import kotlinx.android.synthetic.main.activity_checkout.*
+import org.koin.android.ext.android.inject
 import java.util.*
 
 class CheckoutActivity : BaseActivity(), CheckoutView {
@@ -28,19 +33,19 @@ class CheckoutActivity : BaseActivity(), CheckoutView {
     private lateinit var comments: String
     private lateinit var presenter: CheckoutPresenter
 
+    private val preferencesRepository: PreferencesRepository by inject()
+    private val authService: AuthService by inject()
+    private val databaseService: ClientDatabaseService by inject()
+    private val cartDao: CartDao by inject()
+
     private var payCash = true
     private val orderId = UUID.randomUUID().toString().replace("-", "").subSequence(0, 10).toString()
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_checkout)
 
-        val authService = (application as JustJavaApp).authService
-        val preferencesRepo = (application as JustJavaApp).preferencesRepo
-        val database = (application as JustJavaApp).databaseService
-        val cart = (application as JustJavaApp).cartDatabase.cartDao()
-
-        presenter = CheckoutPresenter(this, authService, preferencesRepo, database, cart)
+        presenter = CheckoutPresenter(this, authService, preferencesRepository, databaseService, cartDao)
 
         rgPayment.setOnCheckedChangeListener { _, checkedId ->
             val text = findViewById<RadioButton>(checkedId).text

app/src/main/java/com/marknkamau/justjava/ui/drinkdetails/DrinkDetailsActivity.kt

@@ -7,12 +7,14 @@ import com.marknkamau.justjava.JustJavaApp
 
 import com.marknkamau.justjava.R
 import com.marknjunge.core.model.CoffeeDrink
+import com.marknkamau.justjava.data.local.CartDao
 import com.marknkamau.justjava.data.models.CartItem
 import com.marknkamau.justjava.ui.BaseActivity
 import com.squareup.picasso.Picasso
 
 import kotlinx.android.synthetic.main.activity_drink_details.*
 import kotlinx.android.synthetic.main.content_drink_details.*
+import org.koin.android.ext.android.inject
 
 class DrinkDetailsActivity : BaseActivity(), DrinkDetailsView, View.OnClickListener {
 
@@ -23,13 +25,12 @@ class DrinkDetailsActivity : BaseActivity(), DrinkDetailsView, View.OnClickListe
     private lateinit var drink: CoffeeDrink
     private var quantity: Int = 0
     private lateinit var presenter: DrinkDetailsPresenter
+    private val cartDao: CartDao by inject()
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_drink_details)
 
-        val cartDao = (application as JustJavaApp).cartDatabase.cartDao()
-
         presenter = DrinkDetailsPresenter(this, cartDao)
 
         drink = intent.extras.getParcelable(DRINK_KEY) as CoffeeDrink

app/src/main/java/com/marknkamau/justjava/ui/login/LogInActivity.kt

@@ -6,25 +6,29 @@ import android.text.TextUtils
 import android.view.View
 import android.widget.Toast
 import androidx.appcompat.app.AppCompatActivity
+import com.marknjunge.core.auth.AuthService
+import com.marknjunge.core.data.firebase.ClientDatabaseService
 import com.marknkamau.justjava.JustJavaApp
 import com.marknkamau.justjava.R
+import com.marknkamau.justjava.data.local.PreferencesRepository
 import com.marknkamau.justjava.ui.signup.SignUpActivity
 import com.marknkamau.justjava.utils.trimmedText
 import kotlinx.android.synthetic.main.activity_log_in.*
+import org.koin.android.ext.android.inject
 
 class LogInActivity : AppCompatActivity(), LogInView, View.OnClickListener {
     private lateinit var email: String
     private lateinit var presenter: LogInPresenter
 
+    private val preferencesRepository: PreferencesRepository by inject()
+    private val authService: AuthService by inject()
+    private val databaseService: ClientDatabaseService by inject()
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_log_in)
 
-        val preferencesRepository = (application as JustJavaApp).preferencesRepo
-        val authService = (application as JustJavaApp).authService
-        val database = (application as JustJavaApp).databaseService
-
-        presenter = LogInPresenter(this, preferencesRepository, authService, database)
+        presenter = LogInPresenter(this, preferencesRepository, authService, databaseService)
         presenter.checkSignInStatus()
 
         btnLogin.setOnClickListener(this)

app/src/main/java/com/marknkamau/justjava/ui/previousOrder/PreviousOrderActivity.kt

@@ -12,15 +12,19 @@ import androidx.recyclerview.widget.LinearLayoutManager
 import android.view.View
 import android.widget.LinearLayout
 import android.widget.Toast
+import com.marknjunge.core.auth.AuthService
+import com.marknjunge.core.data.firebase.ClientDatabaseService
 import com.marknkamau.justjava.JustJavaApp
 import com.marknkamau.justjava.R
 import com.marknkamau.justjava.data.local.PreferencesRepository
 import com.marknjunge.core.model.Order
 import com.marknjunge.core.model.OrderItem
+import com.marknjunge.core.mpesa.MpesaInteractor
 import com.marknkamau.justjava.data.network.MyFirebaseMessagingService
 import com.marknkamau.justjava.utils.formatForApp
 import kotlinx.android.synthetic.main.activity_previous_order.*
 import kotlinx.android.synthetic.main.include_order_details.*
+import org.koin.android.ext.android.inject
 import timber.log.Timber
 
 class PreviousOrderActivity : AppCompatActivity(), PreviousOrderView {
@@ -37,22 +41,22 @@ class PreviousOrderActivity : AppCompatActivity(), PreviousOrderView {
 
     private lateinit var orderItemsAdapter: OrderItemsAdapter
     private lateinit var presenter: PreviousOrderPresenter
-    private lateinit var broadcastManager: androidx.localbroadcastmanager.content.LocalBroadcastManager
     private lateinit var broadcastReceiver: BroadcastReceiver
-    private lateinit var preferencesRepo: PreferencesRepository
     private lateinit var order: Order
 
+    private val preferencesRepository: PreferencesRepository by inject()
+    private val authService: AuthService by inject()
+    private val databaseService: ClientDatabaseService by inject()
+    private val mpesaInteractor: MpesaInteractor by inject()
+    private val broadcastManager by lazy { LocalBroadcastManager.getInstance(this) }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_previous_order)
 
-        broadcastManager = (application as JustJavaApp).broadcastManager
         order = intent.getParcelableExtra(ORDER_KEY)
 
-        val mpesa = (application as JustJavaApp).mpesaInteractor
-        preferencesRepo = (application as JustJavaApp).preferencesRepo
-        val authService = (application as JustJavaApp).authService
-        presenter = PreviousOrderPresenter(this, (application as JustJavaApp).databaseService, mpesa, authService)
+        presenter = PreviousOrderPresenter(this, databaseService, mpesaInteractor, authService)
 
         updateViews(order)
 
@@ -132,7 +136,7 @@ class PreviousOrderActivity : AppCompatActivity(), PreviousOrderView {
         }
 
         btnPay.setOnClickListener {
-            val phoneNumber = preferencesRepo.getUserDetails().phone
+            val phoneNumber = preferencesRepository.getUserDetails().phone
             val dialog = AlertDialog.Builder(this)
                     .setMessage("Are you sure you want to pay Ksh. 1 using $phoneNumber?\nThe money will be automatically refunded by Safaricom the following day.")
                     .setTitle("Confirm payment")