Retrofit Basic Learning

AndroidMainfest.xml

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

ApiInterface.kt

package com.example.coroutinelearning.retrofits

import com.example.coroutinelearning.entity.Root
import retrofit2.Response
import retrofit2.http.GET
import retrofit2.http.Query

interface ApiInterface {

    @GET("/api/users")
    suspend fun getAllUser(
        @Query("page") currentPage: Int, @Query("per_page") pageSize: Int
    ): Response<Root>
    
}

AppDatabase.kt

package com.example.coroutinelearning.database

import android.content.Context
import androidx.room.Database
import androidx.room.Room
import androidx.room.RoomDatabase
import com.example.coroutinelearning.entity.Customer
import com.example.coroutinelearning.entity.User

@Database(entities = [User::class, Customer::class], version = 1, exportSchema = false)
abstract class AppDatabase: RoomDatabase() {

    abstract fun getUserDao(): UserDao
    abstract fun getCustomerDao(): CustomerDao

    companion object{
        private var INSTANCE: AppDatabase? = null
        private const val DB_NAME = "database"

        fun getDatabase(context: Context): AppDatabase {
            return INSTANCE ?: synchronized(this){
                val instance = Room.databaseBuilder(
                    context.applicationContext,
                    AppDatabase::class.java,
                    DB_NAME
                ).build()
                INSTANCE = instance
                instance
            }
        }
    }
}

build.gradle

    //retrofit
    implementation "com.squareup.retrofit2:retrofit:2.9.0"
    implementation 'com.squareup.retrofit2:converter-gson:2.9.0'
    implementation 'com.squareup.okhttp3:logging-interceptor:5.0.0-alpha.1'

customer_list.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">


    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/userRecyclerView"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginTop="24dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Switch
        android:id="@+id/switchDataLoad"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:text="Switch"
        app:layout_constraintBottom_toTopOf="@+id/userRecyclerView"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toEndOf="@+id/textView"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.0" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:text="Online Data"
        android:textColor="#6C0606"
        android:textStyle="bold"
        app:layout_constraintBottom_toTopOf="@+id/userRecyclerView"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>c

customer_list_adapter.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginBottom="10dp">

    <androidx.cardview.widget.CardView
        android:id="@+id/userCard"
        android:layout_width="0dp"
        android:layout_height="100dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <androidx.constraintlayout.widget.ConstraintLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">


            <View
                android:id="@+id/divider2"
                android:layout_width="1dp"
                android:layout_height="0dp"
                android:layout_marginStart="120dp"
                android:background="?android:attr/listDivider"
                android:visibility="invisible"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent"
                tools:visibility="invisible" />

            <ImageView
                android:id="@+id/imgUser"
                android:layout_width="0dp"
                android:layout_height="0dp"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintEnd_toStartOf="@+id/divider2"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent"
                tools:srcCompat="@tools:sample/avatars" />

            <TextView
                android:id="@+id/txtName"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_marginStart="16dp"
                android:layout_marginTop="17dp"
                android:layout_marginEnd="8dp"
                android:fontFamily="sans-serif-black"
                android:text="TextView"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintHorizontal_bias="0.0"
                app:layout_constraintStart_toEndOf="@+id/divider2"
                app:layout_constraintTop_toTopOf="parent" />

            <TextView
                android:id="@+id/txtEmailId"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_marginStart="16dp"
                android:layout_marginTop="8dp"
                android:layout_marginEnd="8dp"
                android:layout_marginBottom="8dp"
                android:text="TextView"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toEndOf="@+id/divider2"
                app:layout_constraintTop_toBottomOf="@+id/txtName"
                app:layout_constraintVertical_bias="0.0" />
        </androidx.constraintlayout.widget.ConstraintLayout>
    </androidx.cardview.widget.CardView>
</androidx.constraintlayout.widget.ConstraintLayout>

CustomerDao.kt

package com.example.coroutinelearning.database

import androidx.room.Dao
import androidx.room.Delete
import androidx.room.Insert
import androidx.room.OnConflictStrategy
import androidx.room.Query
import com.example.coroutinelearning.entity.Customer

@Dao
interface CustomerDao {

    @Query("SELECT * FROM customer")
    suspend fun getAll(): List<Customer>

    @Insert(onConflict = OnConflictStrategy.REPLACE)
    suspend fun insertAll(customerList: List<Customer>): LongArray

    @Delete
    suspend fun delete(customer: Customer)

    @Query("DELETE FROM customer")
    suspend fun clearAll()

}

CustomerEntity.kt

package com.example.coroutinelearning.entity

import androidx.room.Entity
import androidx.room.PrimaryKey
import com.google.gson.annotations.SerializedName


data class Root(
    @SerializedName("page") var page: Int? = null,
    @SerializedName("per_page") var perPage: Int? = null,
    @SerializedName("total") var total: Int? = null,
    @SerializedName("total_pages") var totalPages: Int? = null,
    @SerializedName("data") var data: ArrayList<Customer> = arrayListOf(),
    @SerializedName("support") var support: Support? = Support()
)

@Entity(tableName = "customer")
data class Customer(
    @SerializedName("id") @PrimaryKey var id: Int,
    @SerializedName("email") var email: String? = null,
    @SerializedName("first_name") var firstName: String? = null,
    @SerializedName("last_name") var lastName: String? = null,
    @SerializedName("avatar") var avatar: String? = null
)

data class Support(
    @SerializedName("url") var url: String? = null,
    @SerializedName("text") var text: String? = null
)

CustomerListAdapter.kt

package com.example.coroutinelearning.adapter

import android.content.Context
import android.view.LayoutInflater
import android.view.ViewGroup
import androidx.recyclerview.widget.RecyclerView
import com.bumptech.glide.Glide
import com.example.coroutinelearning.databinding.CustomerListAdapterBinding
import com.example.coroutinelearning.entity.Customer

class CustomerListAdapter(val context: Context) :
    RecyclerView.Adapter<CustomerListAdapter.ViewHolder>() {

    private val TAG = CustomerListAdapter::class.simpleName
    private lateinit var binding: CustomerListAdapterBinding
    private var customerList: List<Customer>? = null

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        binding =
            CustomerListAdapterBinding.inflate(LayoutInflater.from(parent.context), parent, false)
        return ViewHolder(binding)
    }

    override fun getItemCount(): Int {
        return customerList?.size ?: 0
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        holder.txtName.text =
            customerList?.get(position)?.firstName + " " + customerList?.get(position)?.lastName
        holder.txtEmail.text = customerList?.get(position)?.email
        Glide.with(context).load(customerList?.get(position)?.avatar).into(holder.imageUser)
    }

    fun setCustomerList(customerList: List<Customer>) {
        this.customerList = customerList
        notifyDataSetChanged()
    }


    class ViewHolder(binding: CustomerListAdapterBinding) : RecyclerView.ViewHolder(binding.root) {
        val txtName = binding.txtName
        val txtEmail = binding.txtEmailId
        val imageUser = binding.imgUser
    }
}

CustomerListFragment.kt

package com.example.coroutinelearning.fragments

import android.os.Bundle
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
import androidx.lifecycle.ViewModelProvider
import androidx.recyclerview.widget.LinearLayoutManager
import com.example.coroutinelearning.adapter.CustomerListAdapter
import com.example.coroutinelearning.databinding.CustomerListBinding
import com.example.coroutinelearning.viewModels.CustomerViewModel

class CustomerListFragment : Fragment() {

    private val TAG = CustomerListFragment::class.simpleName
    private lateinit var binding: CustomerListBinding
    private val mLayoutManager: LinearLayoutManager by lazy {
        LinearLayoutManager(requireContext())
    }
    private val mCustomerListAdapter: CustomerListAdapter by lazy {
        CustomerListAdapter(requireContext())
    }
    private val customerViewModel: CustomerViewModel by lazy {
        ViewModelProvider(requireActivity()).get(CustomerViewModel::class.java)
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
    }

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?
    ): View? {
        binding = CustomerListBinding.inflate(inflater, container, false)
        return binding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        binding.userRecyclerView.adapter = mCustomerListAdapter
        binding.userRecyclerView.layoutManager = mLayoutManager

        if (binding.switchDataLoad.isChecked) loadDataFromServer()
        else loadDataFromDb()

        binding.switchDataLoad.setOnCheckedChangeListener { compoundButton, isChecked ->
            if (isChecked) loadDataFromServer()
            else loadDataFromDb()
        }
    }

    private fun loadDataFromDb() {
        mCustomerListAdapter.setCustomerList(listOf())
        customerViewModel.getCustomerListDB().observe(viewLifecycleOwner) { customerList ->
            customerList?.let {
                mCustomerListAdapter.setCustomerList(customerList)
            }
        }
    }

    private fun loadDataFromServer() {
        mCustomerListAdapter.setCustomerList(listOf())
        customerViewModel.getCustomerList().observe(viewLifecycleOwner) { customerList ->
            customerList?.let {
                mCustomerListAdapter.setCustomerList(customerList)
            }
        }
    }
}

CustomerRepository.kt

package com.example.coroutinelearning.repositories

import android.app.Application
import android.util.Log
import com.example.coroutinelearning.database.AppDatabase
import com.example.coroutinelearning.database.CustomerDao
import com.example.coroutinelearning.entity.Customer
import com.example.coroutinelearning.retrofits.RetrofitHelper

class CustomerRepository(application: Application) {

    private val TAG = CustomerRepository::class.simpleName

    private val appDatabase: AppDatabase
    private val customerDao: CustomerDao

    init {
        appDatabase = AppDatabase.getDatabase(application)
        customerDao = appDatabase.getCustomerDao()
    }

    suspend fun getCustomerList(): List<Customer>? {
        val result = RetrofitHelper.getServices().getAllUser(1, 12)
        val customerData = result.body()?.data
        saveCustomerDataToDB(customerData)
        return customerData
    }

    suspend fun saveCustomerDataToDB(customerData: List<Customer>?) {
        customerData?.let {
            val entrySuccessful = customerDao.insertAll(customerData)
            Log.i(TAG, "customer data entry is successful: $entrySuccessful")
        }
    }

    suspend fun getCustomerListDB(): List<Customer> {
        return customerDao.getAll()
    }


}

CustomerViewModel.kt

package com.example.coroutinelearning.viewModels

import android.app.Application
import androidx.lifecycle.AndroidViewModel
import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.viewModelScope
import com.example.coroutinelearning.entity.Customer
import com.example.coroutinelearning.repositories.CustomerRepository
import kotlinx.coroutines.launch

class CustomerViewModel(application: Application) : AndroidViewModel(application) {

    private val TAG = CustomerViewModel::class.simpleName
    private val repository: CustomerRepository
    private val customerListLiveData: MutableLiveData<List<Customer>?> = MutableLiveData()
    private val customerListDBLiveData = MutableLiveData<List<Customer>>()

    init {
        repository = CustomerRepository(application)
    }

    fun getCustomerList(): MutableLiveData<List<Customer>?> {
        viewModelScope.launch {
            val customerList = repository.getCustomerList()
            customerListLiveData.value = customerList
        }
        return customerListLiveData
    }

    fun getCustomerListDB(): MutableLiveData<List<Customer>> {
        viewModelScope.launch {
            val customerList = repository.getCustomerListDB()
            customerListDBLiveData.value = customerList
        }
        return customerListDBLiveData
    }

}

RetrofitClient.kt

package com.example.coroutinelearning.retrofits

import okhttp3.OkHttpClient
import okhttp3.logging.HttpLoggingInterceptor
import retrofit2.Retrofit
import retrofit2.converter.gson.GsonConverterFactory

object RetrofitHelper{

    private const val baseUrl = "https://reqres.in"
    private val mHttpLoginInterceptor = HttpLoggingInterceptor()
        .setLevel(HttpLoggingInterceptor.Level.BODY)

    private val mOkHttpClient = OkHttpClient.Builder()
        .addInterceptor(mHttpLoginInterceptor)
        .build()

    fun getInstance() : Retrofit {
        return Retrofit.Builder()
            .baseUrl(baseUrl)
            .addConverterFactory(GsonConverterFactory.create())
            .client(mOkHttpClient)
            .build()
    }

    fun getServices() : ApiInterface{
        return getInstance().create(ApiInterface::class.java)
    }

}