Implementing Google Authentication in Android Studio with Firebase

Table of Contents

Introduction

Authentication is a fundamental component of most mobile applications, providing a secure and convenient way for users to access their accounts. Google Authentication is a popular choice for many developers because it offers a seamless login experience and enhances user trust. In this article, we will guide you through the process of implementing Google Authentication in an Android Studio project using Firebase Authentication

Prerequisites

Before you begin, make sure you have the following prerequisites in place:

Android Studio: Ensure that you have Android Studio installed on your computer.
Firebase Project: Create a Firebase project on the Firebase Console (https://console.firebase.google.com/) and link it to your Android Studio project.
Google Services JSON: Download the google-services.json file from your Firebase project and add it to your Android Studio project’s app folder.
Dependencies: Add the necessary dependencies to your app-level build.gradle file.

implementation 'com.google.firebase:firebase-auth:21.0.1'
implementation 'com.google.android.gms:play-services-auth:20.0.1'

Now, let’s dive into the steps to implement Google Authentication in your Android app.

Step 1: Configure Firebase

First, make sure you’ve configured Firebase in your Android Studio project by adding the google-services.json file to your app folder and adding the Firebase SDK dependencies to your app-level build.gradle file, as shown in the prerequisites.

Step 2: Design the User Interface

Create a user-friendly login interface for your app. You can use XML layout files to design the login screen. Typically, this screen should have a “Sign in with Google” button and other relevant UI elements like text fields for email and password (if you plan to offer multiple login methods).

Step 3: Initialize Firebase Authentication

In your app’s main activity or application class, initialize Firebase Authentication by adding the following code:

FirebaseAuth mAuth = FirebaseAuth.getInstance();

This code initializes the Firebase Authentication instance.

Step 4: Implement Google Sign-In

To implement Google Authentication, you need to set up a Google Sign-In button and handle the sign-in process. Here’s how you can do it:

Create a GoogleSignInClient object:

GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
        .requestIdToken(getString(R.string.default_web_client_id))
        .requestEmail()
        .build();

GoogleSignInClient mGoogleSignInClient = GoogleSignIn.getClient(this, gso);

2.Add an onClickListener to your “Sign in with Google” button:

signInButton.setOnClickListener(view -> {
    Intent signInIntent = mGoogleSignInClient.getSignInIntent();
    startActivityForResult(signInIntent, RC_SIGN_IN);
});

In this code, RC_SIGN_IN is a constant integer used to identify the sign-in request. You can define it in your activity or fragment.

Handle the sign-in result:

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    if (requestCode == RC_SIGN_IN) {
        Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(data);
        try {
            // Google Sign In was successful, authenticate with Firebase
            GoogleSignInAccount account = task.getResult(ApiException.class);
            firebaseAuthWithGoogle(account.getIdToken());
        } catch (ApiException e) {
            // Google Sign In failed, handle it appropriately
            Log.w(TAG, "Google sign in failed", e);
        }
    }
}

4.Authenticate with Firebase:

private void firebaseAuthWithGoogle(String idToken) {
    AuthCredential credential = GoogleAuthProvider.getCredential(idToken, null);
    mAuth.signInWithCredential(credential)
        .addOnCompleteListener(this, task -> {
            if (task.isSuccessful()) {
                // Sign in success, update UI with the signed-in user's information
                FirebaseUser user = mAuth.getCurrentUser();
                // Handle user data or navigate to the main screen
            } else {
                // If sign in fails, display a message to the user.
                Log.w(TAG, "signInWithCredential:failure", task.getException());
                // Handle failed sign-in
            }
        });
}

With these steps, you can implement Google Authentication in your Android app using Firebase. Users can now sign in securely with their Google accounts, and you can access their information as needed for your app

Conclusion

Implementing Google Authentication in Android Studio with Firebase is a crucial step in ensuring a smooth and secure user experience for your app. By following the steps outlined in this article, you can integrate Google Sign-In seamlessly and take advantage of Firebase Authentication’s powerful features. This not only simplifies the login process but also enhances the security and trustworthiness of your mobile application. Happy coding!