Integrate Google sign-in in Android App

Integrate Google sign-in in Android App - Kotlin

Published: 31 December 2020

Prerequisites:

Android version >= Android 4.1 (Jelly Bean) which includes the Google Play Store
Latest version of the Android SDK, including the SDK Tools component

Steps to Integrate

Step 1:

Create a new Android kotlin project.

Step 2:

Add Google’s Maven repository in project level build.gradle file.

allprojects {
    repositories {
        google()
        // If you're using a version of Gradle lower than 4.1, you must instead use:
        // maven {
        //     url 'https://maven.google.com'
        // }
    }
}

Step 3:

Add dependency in app level build.gradle file.

dependencies {
        implementation 'com.google.android.gms:play-services-auth:19.0.0'
    }

Step 4:

Configure Google Sign-in and the GoogleSignInClient object in onCreate() method.

// Configure sign-in to request the user's ID, email address, and basic
// profile. ID and basic profile are included in DEFAULT_SIGN_IN.
var gso:GoogleSignInOptions = GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
   .requestEmail()
   .build()

// Build a GoogleSignInClient with the options specified by gso.
var mGoogleSignInClient:GoogleSignInClient = GoogleSignIn.getClient(this, gso);

Step 5:

Add a sign-in button to your xml layout.

<com.google.android.gms.common.SignInButton
 android:id="@+id/sign_in_button"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content" /> 

Step 6:

Add code in onCreate method to make the sign-in button functional.

var signInButton: SignInButton = findViewById(R.id.sign_in_button)
signInButton.setSize(SignInButton.SIZE_STANDARD)  //Optional
signInButton.setOnClickListener{
   signIn()
}

Implement the signIn() method

private fun signIn() {
   val signInIntent: Intent = mGoogleSignInClient.getSignInIntent()
   startActivityForResult(signInIntent, RC_SIGN_IN)
}

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
   super.onActivityResult(requestCode, resultCode, data)
     if (requestCode == RC_SIGN_IN) {
       val task = GoogleSignIn.getSignedInAccountFromIntent(data)
       handleSignInResult(task)
   }
}

Implement the handleSignInResult() method. If the sign-in is successful, update the UI in this method.

private fun handleSignInResult(completedTask: Task<GoogleSignInAccount>){
   try {
       val account = completedTask.getResult(ApiException::class.java)
       // Signed in successfully, Update the UI here
       Toast.makeText(context, "Sign in successful", Toast.LENGTH_SHORT).show()
   } catch (e: ApiException) {
       // The ApiException status code indicates the detailed failure reason.
       // Please refer to the GoogleSignInStatusCodes class reference for more information.
       Toast.makeText(context, "Sign in failed: "+ e.getStatusCode(), Toast.LENGTH_SHORT).show()
   }
}

Step 7:

When integrating google sign-in we have to use Firebase or App Signing in Google Play console. In this example we are using Firebase. Login to Firebase console.

Create a new project
Add project name
Add Android App

Open Gradle tab in your Android Studio Go to app/android/signingReport and run.

sha

SHA-1 key will be generated in the bottom tab in your Android studio.

sha-code

Use this SHA-1 key to register the app in firebase.

Download the google-services.json and add this to your “app” folder.

Check if project level build.gradle has the required code.

buildscript {
  repositories {
    // Check that you have the following line (if not, add it):
    google()  // Google's Maven repository
  }
  dependencies {
    ...
    // Add this line
    classpath 'com.google.gms:google-services:4.3.4'
  }
}

allprojects {
  ...
  repositories {
    // Check that you have the following line (if not, add it):
    google()  // Google's Maven repository
    ...
  }
}

Check if the app level build.gradle file has the required code.

apply plugin: 'com.android.application'
// Add this line
apply plugin: 'com.google.gms.google-services'

dependencies {
  // Import the Firebase BoM
  implementation platform('com.google.firebase:firebase-bom:26.2.0')

  // Add the dependencies for the desired Firebase products
  // https://firebase.google.com/docs/android/setup#available-libraries
}

Go to Project Overview/ Project settings / General /Public settings

setting1

Add a support email.

setting3

Now run the app and test. Feel free to download the source code from Github