Firebase Login and Authentication: Android Tutorial

Step 5: Click “Add Project“.

Step 6: Enter the required project details and click Submit.

Step 7: After creating a project, you will see the following image of your project dashboard.

All Firebase services are displayed here and you can use any of them.

Step 8: In this blog, we are interested in the authentication part, so click the Authentication button and then switch to Login method ” Tab.

Step 9: In our example, we are logging in via email. So click the “Edit” button next to the “Email/Password” option and you will see the following screen.

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Step 10: Enable email/password login and click ” Save “. You are done with the Firebase website part.

Step 11: Return to your project in Android Studio and click Tools > Firebase > Authentication .

Step 12: We are almost done, now we have to add our project in Android Studio with the project we created in the Firebase. So click “Email and Password Authentication“. Here we have two options namely “Connect to Firebase” and “Add Firebase authentication to your app”. First we need to connect our project to Firebase, so click on the “Connect to Firebase” button.

Step 13: A list of projects associated with your email will appear and you need to select the project you created earlier on Firebase and then on “Connect to Firebase“.

Step 14: Now your project in Android Studio is connected to the existing one in Firebase add some dependencies, so click “Add Firebase authentication to your app” (this is the second option we found in step number 12). A dialog box will open. Click ” Accept Changes” and it will automatically add all dependencies to your project.

Phew! Finally, we’re done with all the steps required to deploy our Android Studio project with Firebase to connect for authentication. Now let’s get to the coding part.

As mentioned before, in our B example four activities:

1. MainActivity: This is the main activity of the application. The user will be redirected to this activity if the user is successfully logged in or created a new account. In the MainActivity we have options to change the password and log out.
2. LoginAcitivty: This activity is used to login the user to the application and after successful login transfer the user to MainActivity. It contains two EditText to take email and password from user. Two buttons for signup and signup (the signup button transfers the user to the SignupActivity) and a TextView that transfers the user to the ForgotPasswordActivity.
3. SignupActivity: This activity is used to register the user in the application and after successful registration transfer the user to the main activity. It contains two EditText to take email and password from user for registration. Two buttons for login and login (the login button redirects the user to the login activity).
4. ForgotPasswordActivity: This activity is used to send the Forgot Password link to the user to set a new password. The reset link will be sent to the user’s email id.

Register a user with email and password

To register a user with email and password, you must first create an instance of FirebaseAuth .

private latinit var auth: FirebaseAuth

Now initialize the FirebaseAuth instance in the onCreate() method.

auth = FirebaseAuth.getInstance()

To login a user with email and password we can use createUserWithEmailAndPassword() method. This method takes email and password as parameters, validates them, and then creates a new user.

auth.createUserWithEmailAndPassword(email, password).addOnCompleteListener(this, OnCompleteListener{ task -> if(task.isSuccessful){ Toast.makeText(this, “Successfully Registered”, Toast.LENGTH_LONG).show() valid intent = Intent(this, MainActivity::class.java) startActivity(intent) finish() }else { Toast.makeText(this, “Registration Failed”, Toast.LENGTH_LONG).show() } })

That’s it. Your user will be registered and you can see the registered user on the Firebase website in the Authentication section and then on the Users tab. If you try to register more than once with the same email address, you will receive an error message or, in simple words, your task will not be successful.

The full code of activity_signup.xml can be found here and SignupActivity.kt by here.

Register a user with email and password

In the previous section we saw how to register a user with email and password. Now we need to login the user by authenticating the email and password entered by the user.

First, declare an instance of FirebaseAuth.

private latinit var auth: FirebaseAuth

Now initialize the FirebaseAuth instance in the onCreate() method.

auth = FirebaseAuth.getInstance()

To sign in a user with email and password, we have a method called signInWithEmailAndPassword() . This method takes email and password as parameters, validates them, and then logs a user into your application if validation succeeds. The same code follows:

auth.signInWithEmailAndPassword(email, password).addOnCompleteListener(this, OnCompleteListener { task -> if(task.isSuccessful) { Toast.makeText(this, “Successfully Logged In”, Toast .LENGTH_LONG ).show() val intention = Intent(this, MainActivity::class.java) startActivity(intent) finish() }else { Toast.makeText(this, “Login Failed”, Toast.LENGTH_LONG).show() } } )

Full code of activity_login.xml can be found here and LoginActivity.kt from here .

Email the link to change the password

Sometimes the user forgot their password and in this case your application should provide a way to reset the password. Things get easier when you use Firebase. In Firebase you can use sendPasswordResetEmail() method to send password reset link to user and by clicking on this link user can set newer password.

First, create an instance of FirebaseAuth.

private latinit var auth: FirebaseAuth

Now initialize the FirebaseAuth instance in the onCreate() method.

auth = FirebaseAuth.getInstance()

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After that you can use sendPasswordResetEmail() to send the reset email to the user. This method takes email as a parameter.

auth.sendPasswordResetEmail(email).addOnCompleteListener(this, OnCompleteListener { task -> if (task.isSuccessful) { Toast.makeText(this, “Reset the link sent to your email”, Toast.LENGTH_LONG) . show() } else { Toast.makeText(this, “Unable to send reset mail”, Toast.LENGTH_LONG) .show() } })

Check your email, you received a reset link 🙂

The full code of activity_forgot_password_activity.xml can be found here and ForgotPasswordActivity.kt here .

Check if a user is logged in or not

To check if a user is logged in or not we can use getCurrentUser() Method to get the status of a user.

if(auth.currentUser == null){ val intention = Intent(this, LoginActivity::class.java) startActivity(intent) finish() }else{ Toast.makeText(this, “Already logged in”, Toast .LENGTH_LONG).show() }

In the above code, if the user is logged in, a toast is shown, and if a user is not logged in, the LoginActivtiy is started.

Update Password

You can update a user’s password by using the updatePassword() method. This method takes the new password as a parameter and updates the password for you.

So create a FirebaseAuth instance and initialize the instance and after that use the updatePassword() method like this:

auth .currentUser ?.updatePassword(password) ?.addOnCompleteListener(this, OnCompleteListener { task -> if (task.isSuccessful) { Toast.makeText(this, “Password changed successfully”, Toast.LENGTH_LONG) .show() finish() } else { Toast.makeText(this, “Password not changed”, Toast.LENGTH_LONG) .show() } })

Similarly, you can change the email by updateEmail() method in the same way as in the case of updatePassword().