How to connect to internet using Retrofit, Moshi, Livedata in Android 11

Here we are going to create a network connection using the Glide, Retrofit, Moshi custom library with LiveData and Coroutines. So to begin with create a project with name <Any Name> or download the starter library(InternetStarter) and change the name.

Step 1: Update the dependancies.

Better to avoid changing these dependencies. Your project might not work if any items are modified.

build.gradle(:project name)

// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
    ext{
        multidex_version = "2.0.1"
        kotlin_version = "1.4.32"
        version_gradle = "4.1.2"
        version_core = '1.6.0'
        version_glide = '4.12.0'
        version_kotlin_coroutines = "1.3.7"
        version_lifecycle = '2.3.1'
        version_moshi = '1.11.0'
        version_navigation = "1.0.0"
        version_retrofit = "2.9.0"
        version_retrofit_coroutines_adapter = "0.9.2"
        version_recyclerview = '1.2.1'
        version_constraint_layout= "2.1.0-beta02"
    }
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:4.1.0'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath "android.arch.navigation:navigation-safe-args-gradle-plugin:$version_navigation"
    }
}

allprojects {
    repositories {
        google()
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

build.gradle(:app)

plugins {
    id 'com.android.application'
    id 'kotlin-android'
    id 'kotlin-kapt'
    id 'androidx.navigation.safeargs'
}

android {
    compileSdkVersion 30


    buildFeatures{
        dataBinding true
    }

    defaultConfig {
        applicationId "com.blogspot.howtouseinternet"
        minSdkVersion 19
        targetSdkVersion 30
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = JavaVersion.VERSION_1_8.toString()
    }
    defaultConfig{
        multiDexEnabled = true
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])

    //Material Ui
    implementation 'com.google.android.material:material:1.4.0'
    // Kotlin
    // implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$version_kotlin"
    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"

    // Constraint Layout
    implementation "androidx.constraintlayout:constraintlayout:$version_constraint_layout"

    // ViewModel and LiveData
    // implementation "androidx.lifecycle:lifecycle-extensions:$version_lifecycle_extensions"
    implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:$version_lifecycle"

    // Navigation
    implementation "android.arch.navigation:navigation-fragment-ktx:$version_navigation"
    implementation "android.arch.navigation:navigation-ui-ktx:$version_navigation"

    // Core with Ktx
    implementation "androidx.core:core-ktx:$version_core"

    // Moshi
    implementation "com.squareup.moshi:moshi:$version_moshi"
    implementation "com.squareup.moshi:moshi-kotlin:$version_moshi"


    // Retrofit
    implementation "com.squareup.retrofit2:retrofit:$version_retrofit"
    implementation "com.squareup.retrofit2:converter-scalars:$version_retrofit"

    // Retrofit with Moshi Converter
    implementation "com.squareup.retrofit2:converter-moshi:$version_retrofit"

    // Coroutines - Deprecated - No more required
    // implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:$version_kotlin_coroutines"
    // implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:$version_kotlin_coroutines"

    // Retrofit Coroutines Support - Deprecated - No more required
    // implementation "com.jakewharton.retrofit:retrofit2-kotlin-coroutines-adapter:$version_retrofit_coroutines_adapter"

    // Glide
    implementation "com.github.bumptech.glide:glide:$version_glide"

    // RecyclerView
    implementation "androidx.recyclerview:recyclerview:$version_recyclerview"
    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
    implementation 'androidx.lifecycle:lifecycle-livedata-ktx:2.3.1'

    //Multidex
    implementation "androidx.multidex:multidex:$multidex_version"
}

Step 2: Create a Fragment with ViewModel to test the dependancies 

• Create a package inside main project with name home. (Right Click -> new -> package)
• Right click the package and select New -> Fragment -> Fragment + View Model
• Let the Fragment be created

    Now Fragment can't run on its own. It needs an activity and navigation host. 

• Add the fragment in the activity_main.xml
• Use the default navigation host. 

<fragment xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/nav_host_fragment"
    android:name="androidx.navigation.fragment.NavHostFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:defaultNavHost="true"
    app:navGraph="@navigation/nav_graph" />

    Now this fragment needs a nav graph in order to switch between fragments. Create a navigation graph        by using the following steps.

• Right click on the res folder in Project Tree.
• Click new -> Android Resource File 
• Select resource type : Navigation , name : nav_graph
• Add the file 
  
  

  

  
  
  

    At the end of this step a nav_graph file will be created. Open the file. 

• Click the Add a destination button and select the MainFragment
• 

Now go back to the main_activity and add the navGraph

Complete Starter can be downloaded here : https://github.com/PijushManna/InternetStarter

Step 3: Manage network requests

Add a network project. Inside the project maintain the API requests.

NetworkApi.kt : 

package com.blogspot.howtouseinternet.network

import retrofit2.Call
import retrofit2.Retrofit
import retrofit2.converter.scalars.ScalarsConverterFactory
import retrofit2.http.GET

private const val BASE_URL = "https://mars.udacity.com/"

private val retrofit = Retrofit.Builder()
    .addConverterFactory(ScalarsConverterFactory.create())
    .baseUrl(BASE_URL)
    .build()

interface NetworkApis{
    @GET("realestate")
    fun getProperties():
            Call<String>
}

object MarsApi{
    val marsProperties : NetworkApis by lazy {
        retrofit.create(NetworkApis::class.java)
    }
}