Implementation

• Install the Amplify CLI

  AWS Amplify CLI depends on Node.js, refer to the prerequisites section in the introduction to install Node.js

  To install AWS Amplify CLI, open a Terminal and type the following command:

  ## Install Amplify CLI
  npm install -g @aws-amplify/cli
  
  ## Verify installation and version
  amplify --version
  # Scanning for plugins...
  # Plugin scan successful
  # 4.29.4

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• Initialize an Amplify Backend

  To create the basic structure of our backend, we first need to initialize the amplify project directory and to create our cloud backend.

  Open a Terminal and change to the directory of your project. For example, if you created your project in the folder ~/AndroidStudioProjects/android-getting-started, you can type:
  

  cd ~/AndroidStudioProjects/android-getting-started  

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  Verify you are in the correct directory, it should look like this:
  

  ➜  android-getting-started git:(main) ✗ ls -al
  total 32
  drwxr-xr-x  14 stormacq  admin   448 Oct  6 14:06 .
  drwxr-xr-x  16 stormacq  admin   512 Oct  6 11:28 ..
  -rw-r--r--   1 stormacq  admin   208 Oct  6 14:04 .gitignore
  drwxr-xr-x   6 stormacq  admin   192 Oct  6 14:04 .gradle
  drwxr-xr-x  13 stormacq  admin   416 Oct  6 15:19 .idea
  drwxr-xr-x   8 stormacq  admin   256 Oct  6 14:06 app
  drwxr-xr-x   3 stormacq  admin    96 Oct  6 14:06 build
  -rw-r--r--   1 stormacq  admin   642 Oct  6 14:04 build.gradle
  drwxr-xr-x   3 stormacq  admin    96 Oct  6 14:04 gradle
  -rw-r--r--   1 stormacq  admin  1162 Oct  6 14:04 gradle.properties
  -rwxr--r--   1 stormacq  admin  5296 Oct  6 14:04 gradlew
  -rw-r--r--   1 stormacq  admin  2260 Oct  6 14:04 gradlew.bat
  -rw-r--r--   1 stormacq  admin   437 Oct  6 14:04 local.properties
  -rw-r--r--   1 stormacq  admin    59 Oct  6 14:04 settings.gradle

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  Initialize the Amplify project structure and configuration file. Execute the following command:
  

  amplify init
  
  ? Enter a name for your project (androidgettingstarted): accept the default, press enter
  ? Enter a name for the environment (dev): accept the default, press enter
  ? Choose your default editor: use the arrow key to select your favorite text editor an press enter
  ? Choose the type of app that you're building: android is already selected, press enter
  ? Where is your Res directory: accept the default, press enter
  ? Do you want to use an AWS profile?, Y, press enter
  ? Please choose the profile you want to use: use the arrow keys to select your profile and press enter.

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  You can create a profile using AWS CLI using aws configure --profile <name> if you don't have one yet.

  Amplify initializes your project in the cloud, it might take a few minutes. After a few minutes, you should see a message like:
  

  ✔ Successfully created initial AWS cloud resources for deployments.
  ✔ Initialized provider successfully.
  Initialized your environment successfully.
  
  Your project has been successfully initialized and connected to the cloud!

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• Add Amplify Libraries to your Project

  Amplify for Android is distributed as Apache Maven packages. In this section, you’ll add the packages and other required directives to your build configuration.

  Back to Android Studio, expand Gradle Scripts and open build.gradle (Project: Android_Getting_Started). Add the line mavenCentral() within the repositories block in the buildscript and allprojects blocks.
  

  buildscript {
      ext.kotlin_version = "1.4.10"
      repositories {
          google()
          jcenter()
  
          // Add this line into `repositories` in `buildscript`
          mavenCentral()
      }
      dependencies {
          classpath "com.android.tools.build:gradle:4.0.1"
          classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
  
          // NOTE: Do not place your application dependencies here; they belong
          // in the individual module build.gradle files
      }
  }
  
  allprojects {
      repositories {
          google()
          jcenter()
  
          // Add this line into `repositories` in `buildscript`
          mavenCentral()
      }
  }

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  Under Gradle Scripts, open build.gradle (Module:app) and add the Amplify framework core dependency in the implementations block.
  

  dependencies {
      implementation fileTree(dir: "libs", include: ["*.jar"])
      implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
      implementation 'androidx.core:core-ktx:1.3.2'
      implementation 'androidx.appcompat:appcompat:1.2.0'
      implementation 'com.google.android.material:material:1.2.1'
      implementation 'androidx.constraintlayout:constraintlayout:2.0.1'
      implementation 'androidx.navigation:navigation-fragment-ktx:2.3.0'
      implementation 'androidx.navigation:navigation-ui-ktx:2.3.0'
      testImplementation 'junit:junit:4.13'
      androidTestImplementation 'androidx.test.ext:junit:1.1.2'
      androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
  
      // Amplify core dependency
      implementation 'com.amplifyframework:core:1.4.0'
  }

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  Should you develop in Java or target Android SDK 21 or earlier, please check the documentation for additional configuration changes.

  Now, run Gradle Sync.
  

  

  After a while, you should see
  

  BUILD SUCCESSFUL in 1s

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• Initialize Amplify at Runtime

  Let's create a Backend class to group the code to interact with our backend. I use a singleton design pattern to make it easily available through the application and to ensure the Amplify libraries are initialized only once.

  The class initializer takes care of initializing the Amplify libraries.

  Under java/com.example.androidgettingstarted create a new kotlin file Backend.kt, open it and add this code:
  

  package com.example.androidgettingstarted
  
  import android.content.Context
  import android.util.Log
  import com.amplifyframework.AmplifyException
  import com.amplifyframework.core.Amplify
  
  object Backend {
  
      private const val TAG = "Backend"
  
      fun initialize(applicationContext: Context) : Backend {
          try {
              Amplify.configure(applicationContext)
              Log.i(TAG, "Initialized Amplify")
          } catch (e: AmplifyException) {
              Log.e(TAG, "Could not initialize Amplify", e)
          }
          return this
      }
  }

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  We initialize our singleton Backend object when application launches.

  Under java/com.example.androidgettingstarted create a new kotlin file Application.kt, open it and add this code:
  

  package com.example.androidgettingstarted
  
  import android.app.Application
  
  class AndroidGettingStartedApplication : Application() {
  
      override fun onCreate() {
          super.onCreate()
  
          // initialize Amplify when application is starting
          Backend.initialize(applicationContext)
      }
  }

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  Under manifests, open AndroidManifest.xml and add the name of the application class to the <application> element.
  

      <!-- add the android:name attribute to the application node  -->
      <application
          android:name="AndroidGettingStartedApplication"
          android:allowBackup="true"
          android:icon="@mipmap/ic_launcher"
          android:label="@string/app_name"
          android:roundIcon="@mipmap/ic_launcher_round"
          android:supportsRtl="true"
          android:theme="@style/Theme.GettingStartedAndroid">
  ...

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  While you have this file open, add a couple of permissions the application will require at later steps of this tutorial:
  

      <!-- add these nodes between manifest and application  -->
      <uses-permission android:name="android.permission.INTERNET"/>
      <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
      <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

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• Verify your Setup

  To verify everything works as expected, build and run the project. Click Run icon ▶️ in the toolbar or type ^ R.
  

  To verify everything works as expected, build and run the project.Click  Run  icon  ▶️  in the toolbar or type  ^ R.

  

  There should be no error.
  

  BUILD SUCCESSFUL in 6s
  23 actionable tasks: 8 executed, 15 up-to-date

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