Retrofit with MVVM (Get Api)

activity_test.xml

<?xml version="1.0" encoding="utf-8"?>
<layout
    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"
    >

<androidx.constraintlayout.widget.ConstraintLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".view.Activity.TestActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        />

</androidx.constraintlayout.widget.ConstraintLayout>

</layout>

ApiClient.kt

package com.example.application.network

import retrofit2.Retrofit
import retrofit2.converter.gson.GsonConverterFactory

object ApiClient {

    val BASE_URL: String = "https://jsonplaceholder.typicode.com/"
    var retrofit: Retrofit? = null


    fun getApiData(): Retrofit? {
        if (retrofit == null) {

              val interceptor = HttpLoggingInterceptor()
            interceptor.level = HttpLoggingInterceptor.Level.BODY
            val builder = OkHttpClient.Builder()
                .addInterceptor(interceptor)

        
           retrofit = Retrofit.Builder()
                .baseUrl(BASE_URL)
                .client(builder.build())
                .addConverterFactory(GsonConverterFactory.create())
                .build()
       }
        return retrofit
    }
}

ApiInterface.kt

package com.example.application.network

import com.example.testapi.model.dataModel.PojoItem
import retrofit2.Call
import retrofit2.http.GET

interface ApiInterface {

    @GET("/posts")
    fun getData(): Call<List<PojoItem>>
}

data_item.xml

<?xml version="1.0" encoding="utf-8"?>

<layout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    >

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


    <androidx.cardview.widget.CardView
        android:layout_width="match_parent"
        android:layout_height="170dp"
        android:layout_margin="10dp"
        app:cardElevation="5dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        >

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

            <androidx.appcompat.widget.AppCompatTextView
                android:id="@+id/post_Id"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginStart="20dp"
                android:layout_marginTop="5dp"
                android:text="Id"
                android:textSize="18dp"
                android:textStyle="bold"
                android:textColor="#6C0808"
                app:layout_constraintTop_toTopOf="parent"
                app:layout_constraintStart_toStartOf="parent"

                />

    <androidx.appcompat.widget.AppCompatTextView
        android:id="@+id/post_title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="5dp"
        android:text="Title"
        android:textSize="16dp"
        android:textStyle="bold"
        android:textColor="#051C6E"
        app:layout_constraintTop_toBottomOf="@id/post_Id"
        app:layout_constraintStart_toStartOf="@id/post_Id"

        />

    <androidx.appcompat.widget.AppCompatTextView
        android:id="@+id/post"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="5dp"
        android:text="Post"
        android:textSize="15dp"
        android:textColor="#000"
        app:layout_constraintTop_toBottomOf="@id/post_title"
        app:layout_constraintStart_toStartOf="@id/post_title"
        />


        </androidx.constraintlayout.widget.ConstraintLayout>
    </androidx.cardview.widget.CardView>



</androidx.constraintlayout.widget.ConstraintLayout>
</layout>

PojoItem.kt

package com.example.testapi.model.dataModel

import android.os.Parcelable
import com.google.gson.annotations.SerializedName
import kotlinx.android.parcel.Parcelize

@Parcelize
data class PojoItem(

    @SerializedName("id")
    val id: String,
    @SerializedName("body")
    val body: String,
    @SerializedName("title")
    val title: String
):Parcelable

PostRepository.kt

package com.example.testapi.model.repository


import com.example.application.network.ApiInterface



class PostRepository( private val apiInterface: ApiInterface) {

    fun getPost() = apiInterface.getData()
}

TestActivity.kt

package com.example.testapi.view.Activity

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import androidx.databinding.DataBindingUtil
import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModelProvider
import androidx.lifecycle.observe
import androidx.recyclerview.widget.LinearLayoutManager
import com.example.application.network.ApiInterface
import com.example.application.network.ApiClient
import com.example.testapi.R
import com.example.testapi.databinding.ActivityTestBinding
import com.example.testapi.model.dataModel.PojoItem
import com.example.testapi.model.repository.PostRepository
import com.example.testapi.view.adapter.TestAdapter
import com.example.testapi.viewModel.TestViewModel
import com.example.testapi.viewModel.TestViewModelFactory

class TestActivity : AppCompatActivity() {

    lateinit var binding: ActivityTestBinding
    lateinit var viewModel: TestViewModel

    var list: List<PojoItem> = ArrayList()

    val adapter = TestAdapter(list)

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = DataBindingUtil.setContentView(this, R.layout.activity_test)

        val apiInterface = ApiClient.getApiData()?.create(ApiInterface::class.java)

        val repository  = PostRepository(apiInterface!!)

         viewModel = ViewModelProvider(this, TestViewModelFactory(repository)).get(TestViewModel::class.java)

         binding.recyclerView.adapter = adapter
        binding.recyclerView.layoutManager = LinearLayoutManager(this)



        viewModel.postList.observe(this, Observer {
            Log.d("TAG", "movieList: $it")
            adapter.setData(it)
        })



        viewModel.getAllData()



    }
}

TestAdapter.kt

package com.example.testapi.view.adapter

import android.view.LayoutInflater
import android.view.ViewGroup
import androidx.databinding.DataBindingUtil
import androidx.recyclerview.widget.RecyclerView
import com.example.testapi.R
import com.example.testapi.databinding.DataItemBinding
import com.example.testapi.model.dataModel.PojoItem

class TestAdapter (var list: List<PojoItem>): RecyclerView.Adapter<TestAdapter.ViewHolder>() {

    var dataBinding:DataItemBinding? = null

        override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
            dataBinding = DataBindingUtil.inflate(LayoutInflater.from(parent.context),
                R.layout.data_item,parent ,false)
            return TestAdapter.ViewHolder(dataBinding!!)
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
       val item: PojoItem = list[position]
        holder.bindData(item)
    }

    override fun getItemCount(): Int {
        return list.size
    }

    fun  setData(data: List<PojoItem>){
        this.list = data
        notifyDataSetChanged()
    }


    class ViewHolder (val binding: DataItemBinding) : RecyclerView.ViewHolder(binding.root){
        fun bindData(pojoItem: PojoItem) {

            binding.postTitle.text = pojoItem.title
            binding.post.text = pojoItem.body
            binding.postId.text = pojoItem.id

        }

    }
}

TestViewModel.kt

package com.example.testapi.viewModel

import android.util.Log
import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.ViewModel
import com.example.testapi.model.dataModel.PojoItem
import com.example.testapi.model.repository.PostRepository
import retrofit2.Call
import retrofit2.Callback
import retrofit2.Response

class TestViewModel(val repository: PostRepository): ViewModel() {

    val postList = MutableLiveData<List<PojoItem>>()
 
 // val list = PojoItem(id = "101", title = "Data", body = "TechTree IT")


    fun getAllData(){
        val response = repository.getPost()
        response.enqueue(object : Callback<List<PojoItem>> {
            override fun onResponse(call: Call<List<PojoItem>>,
                                    response: Response<List<PojoItem>>,){

                   postList.postValue(response.body())    //?.plus(list) ?: listOf(list) )
            }


            override fun onFailure(call: Call<List<PojoItem>>, t: Throwable) {
                Log.e("Fail", "${t.message}")
            }
        })
    }

}

TestViewModelFactory.kt

package com.example.testapi.viewModel

import androidx.lifecycle.ViewModel
import androidx.lifecycle.ViewModelProvider
import com.example.testapi.model.repository.PostRepository

class TestViewModelFactory(private val repository: PostRepository): ViewModelProvider.Factory {
    override fun <T : ViewModel?> create(modelClass: Class<T>): T {
            return TestViewModel(repository) as T
    }
}

//get api impimentation