In this tutorial, we will learn how to implement user authentication using Firebase in Android apps. User authentication is a critical component of any application that seeks to protect user data and ensure that only authorized users access certain features or resources. By the end of this tutorial, you will have an Android app that allows users to sign up, log in, and log out using Firebase authentication.
Prerequisites:
- Basic knowledge of Android development using Java or Kotlin
- Familiarity with Android Studio
- A Firebase project
Step 1: Set up Firebase in your Android project
Before you can use Firebase authentication, you need to set up Firebase in your Android app. Follow these steps to connect your app to Firebase:
- Open your Android project in Android Studio.
- Click on Tools > Firebase to open the Firebase Assistant.
- Click on "Authentication" and then on "Connect to Firebase."
- Choose an existing Firebase project or create a new one, then click "Connect."
- Click "Add Firebase Authentication to your app" and then "Accept Changes" to add the necessary dependencies to your project.
Once the setup is complete, you should see the following dependencies added to your app-level build.gradle file:
dependencies { ... implementation 'com.google.firebase:firebase-core:19.0.1' implementation 'com.google.firebase:firebase-auth:21.0.1'}Step 2: Create the Sign Up and Log In UI
Create a new activity named "SignUpActivity" and design the user interface for signing up. You can use EditText views for email and password input, and a Button to submit the form. Similarly, create a new activity named "LogInActivity" for the user login UI. Here's a simple example of how the XML layout for SignUpActivity might look:
<LinearLayout 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" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:padding="16dp" tools:context=".SignUpActivity"> <EditText android:id="@+id/emailEditText" android:layout_width="match_parent" android:layout_height="wrap_content" android:hint="Email" android:inputType="textEmailAddress" /> <EditText android:id="@+id/passwordEditText" android:layout_width="match_parent" android:layout_height="wrap_content" android:hint="Password" android:inputType="textPassword" /> <Button android:id="@+id/signUpButton" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Sign Up" /></LinearLayout>Step 3: Implement Sign Up and Log In Functionality
In the SignUpActivity and LogInActivity, add the following code to initialize the FirebaseAuth instance:
private FirebaseAuth mAuth;@Overrideprotected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_sign_up); mAuth = FirebaseAuth.getInstance();}Now, implement the sign-up functionality in SignUpActivity. Add a click listener to the sign-up button, get the user's email and password, and use the createUserWithEmailAndPassword() method to register the user:
Button signUpButton = findViewById(R.id.signUpButton);signUpButton.setOnClickListener(v -> { String email = emailEditText.getText().toString().trim(); String password = passwordEditText.getText().toString().trim(); mAuth.createUserWithEmailAndPassword(email, password) .addOnCompleteListener(this, task -> { if (task.isSuccessful()) { // Sign up success, update UI with the signed-in user's information FirebaseUser user = mAuth.getCurrentUser(); Toast.makeText(SignUpActivity.this, "Sign up successful.", Toast.LENGTH_SHORT).show(); } else { // If sign up fails, display a message to the user. Toast.makeText(SignUpActivity.this, "Sign up failed.", Toast.LENGTH_SHORT).show(); } });});Similarly, implement the login functionality in LogInActivity using the signInWithEmailAndPassword() method:
Button logInButton = findViewById(R.id.logInButton);logInButton.setOnClickListener(v -> { String email = emailEditText.getText().toString().trim(); String password = passwordEditText.getText().toString().trim(); mAuth.signInWithEmailAndPassword(email, password) .addOnCompleteListener(this, task -> { if (task.isSuccessful()) { // Log in success, update UI with the signed-in user's information FirebaseUser user = mAuth.getCurrentUser(); Toast.makeText(LogInActivity.this, "Log in successful.", Toast.LENGTH_SHORT).show(); } else { // If log in fails, display a message to the user. Toast.makeText(LogInActivity.this, "Log in failed.", Toast.LENGTH_SHORT).show(); } });});Step 4: Implement Log Out Functionality
To allow users to log out, simply call the signOut() method on the FirebaseAuth instance:
Button logOutButton = findViewById(R.id.logOutButton);logOutButton.setOnClickListener(v -> { mAuth.signOut(); Toast.makeText(MainActivity.this, "Logged out successfully.", Toast.LENGTH_SHORT).show();});Conclusion
In this tutorial, we have learned how to implement user authentication using Firebase in Android apps. We created a simple app that allows users to sign up, log in, and log out using Firebase authentication. This should give you a solid foundation for implementing user authentication in your own Android projects. If you are looking to hire Android developers for your project, our team of experienced developers can help you build a secure and robust application.
