Adding Firebase functionality in your app | Part 2 Creating Firebase Authentication

Introduction:
In this post, we will create a Login and Registration Page with Firebase authentication, we will accept the name, email, password of the user and register the user with the Firebase auth library.

Implementation:

1. First, we need to enable authentication for our project, go to the Firebase console, select Authentication from the left panel and then sign-in method, enable email method.
2. In AS, go-to the assistant, in the right panel, select Authentication, click connect to Firebase, it will be in green when connected, second select Add Authentication to the project, Accept changes and finish.
3. Now you can start coding.
4. Create an Empty Activity, named as SignUp
5. Go to SignUp.xml and add the following XML.

	<?xml version="1.0" encoding="utf-8"?>
	<androidx.constraintlayout.widget.ConstraintLayout 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:padding="20dp"
	tools:context="SignUp">
	<TextView
	android:id="@+id/register"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:layout_marginTop="51dp"
	android:text="Sign Up"
	android:textColor="@color/colorPrimary"
	android:textSize="25sp"
	android:textStyle="bold"
	app:layout_constraintEnd_toEndOf="parent"
	app:layout_constraintStart_toStartOf="parent"
	app:layout_constraintTop_toTopOf="parent" />
	<EditText
	android:id="@+id/name"
	android:layout_width="match_parent"
	android:layout_height="50dp"
	android:padding="10dp"
	android:layout_marginTop="30dp"
	android:ems="10"
	android:inputType="textPersonName"
	android:hint="Name"
	app:layout_constraintEnd_toEndOf="parent"
	app:layout_constraintStart_toStartOf="parent"
	app:layout_constraintTop_toBottomOf="@+id/register" />
	<EditText
	android:id="@+id/email"
	android:layout_width="match_parent"
	android:layout_height="50dp"
	android:padding="10dp"
	android:layout_marginTop="42dp"
	android:layout_marginEnd="4dp"
	android:layout_marginRight="4dp"
	android:ems="10"
	android:inputType="textEmailAddress"
	android:hint="Email Address"
	app:layout_constraintEnd_toEndOf="@+id/name"
	app:layout_constraintTop_toBottomOf="@+id/name" />
	<EditText
	android:id="@+id/password"
	android:layout_width="match_parent"
	android:layout_height="50dp"
	android:padding="10dp"
	android:layout_marginStart="2dp"
	android:layout_marginLeft="2dp"
	android:layout_marginTop="48dp"
	android:ems="10"
	android:inputType="text"
	android:hint="Password"
	app:layout_constraintStart_toStartOf="@+id/email"
	app:layout_constraintTop_toBottomOf="@+id/email" />
	<Button
	android:id="@+id/signupButton"
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:layout_marginTop="32dp"
	android:text="Register"
	android:textColor="@android:color/white"
	app:layout_constraintEnd_toEndOf="parent"
	app:layout_constraintStart_toStartOf="parent"
	app:layout_constraintTop_toBottomOf="@+id/password" />
	<TextView
	android:id="@+id/singinLink"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:layout_marginTop="16dp"
	android:text="Already have an account?"
	android:textSize="15sp"
	android:textAllCaps="true"
	android:textColor="@color/colorAccent"
	app:layout_constraintEnd_toEndOf="parent"
	app:layout_constraintStart_toStartOf="parent"
	app:layout_constraintTop_toBottomOf="@+id/signupButton" />
	</androidx.constraintlayout.widget.ConstraintLayout>

view raw layout_signup.xml hosted with ❤ by GitHub

The XML file defines three EditText for user input and Button.

Add the following java code to read the input and create an account with the Firebase

	// I haven't add imported files, but those will be added by clicking Alt + Enter
	public class SignUp extends AppCompatActivity {
	private EditText name, email, password; //out input fields
	private FirebaseAuth firebaseAuth; // firebase auth object
	@Override
	protected void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	setContentView(R.layout.activity_sign_up);
	name = findViewById(R.id.name);
	email = findViewById(R.id.email);
	password = findViewById(R.id.password);
	firebaseAuth = FirebaseAuth.getInstance();
	findViewById(R.id.singinLink).setOnClickListener(new View.OnClickListener() {
	@Override
	public void onClick(View v) {
	startActivity(new Intent(SignUp.this, SignIn.class)); // if account exists go to login page
	}
	});
	findViewById(R.id.signupButton).setOnClickListener(new View.OnClickListener() {
	@Override
	public void onClick(View v) {
	createAccount();
	}
	});
	}
	// function to create account on button click
	private void createAccount() {
	// read inputs
	final String nameText = name.getText().toString().trim();
	final String emailText = email.getText().toString().trim();
	String passwordText = password.getText().toString().trim();
	firebaseAuth.createUserWithEmailAndPassword(emailText, passwordText)
	.addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
	@Override
	public void onComplete(@NonNull Task<AuthResult> task) {
	if(task.isSuccessful()){
	Toast.makeText(getApplicationContext(), "Account Created!", Toast.LENGTH_SHORT).show();
	} else {
	Toast.makeText(getApplicationContext(), "Problem occurred!" + task.getException().getLocalizedMessage(), Toast.LENGTH_SHORT).show();
	}
	}
	});
	}
	}

view raw SignUp.java hosted with ❤ by GitHub

If everything is done correctly, you would be able to create an account with your email, when created check the Firebase console user section and you'll see a new account added.
Now let's implement Login Page

Create a new activity, named SignIn
Go to layout_signin.xml and add the following code:

	<?xml version="1.0" encoding="utf-8"?>
	<androidx.constraintlayout.widget.ConstraintLayout 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:padding="20dp"
	tools:context="SignIn">
	<TextView
	android:id="@+id/textView"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:layout_marginTop="51dp"
	android:layout_marginBottom="411dp"
	android:text="Sign In"
	android:textColor="@color/colorPrimary"
	android:textSize="25sp"
	android:textStyle="bold"
	app:layout_constraintEnd_toEndOf="parent"
	app:layout_constraintStart_toStartOf="parent"
	app:layout_constraintTop_toTopOf="parent" />
	<EditText
	android:id="@+id/emailAddress"
	android:layout_width="match_parent"
	android:layout_height="50dp"
	android:padding="10dp"
	android:layout_marginTop="59dp"
	android:ems="10"
	android:hint="Email Address"
	android:inputType="textEmailAddress"
	app:layout_constraintEnd_toEndOf="parent"
	app:layout_constraintStart_toStartOf="parent"
	app:layout_constraintTop_toBottomOf="@+id/textView" />
	<EditText
	android:id="@+id/passwordSignin"
	android:layout_width="match_parent"
	android:layout_height="50dp"
	android:padding="10dp"
	android:layout_marginTop="50dp"
	android:ems="10"
	android:hint="Password"
	android:inputType="textPassword"
	app:layout_constraintStart_toStartOf="@+id/emailAddress"
	app:layout_constraintTop_toBottomOf="@+id/emailAddress" />
	<Button
	android:id="@+id/siginButton"
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:layout_marginTop="50dp"
	android:text="Login"
	android:textColor="@android:color/white"
	app:layout_constraintEnd_toEndOf="parent"
	app:layout_constraintStart_toStartOf="parent"
	app:layout_constraintTop_toBottomOf="@+id/passwordSignin" />
	<TextView
	android:id="@+id/registerLink"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:layout_marginTop="29dp"
	android:text="Create new account"
	android:textSize="15sp"
	android:textAllCaps="true"
	android:textColor="@color/colorAccent"
	app:layout_constraintEnd_toEndOf="parent"
	app:layout_constraintStart_toStartOf="parent"
	app:layout_constraintTop_toBottomOf="@+id/siginButton" />
	</androidx.constraintlayout.widget.ConstraintLayout>

view raw layout_signing.xml hosted with ❤ by GitHub

Here we have created two input fields to accept email and password
Add the following java code in SignIn.java

	//import everything
	public class SignIn extends AppCompatActivity {
	private EditText email;
	private EditText password;
	private Button signIn;
	private TextView register;
	private FirebaseAuth firebaseAuth;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	setContentView(R.layout.activity_sign_in);
	email = findViewById(R.id.emailAddress);
	password = findViewById(R.id.passwordSignin);
	signIn = findViewById(R.id.siginButton);
	register = findViewById(R.id.registerLink);
	loading = findViewById(R.id.loading);
	firebaseAuth = FirebaseAuth.getInstance();
	register.setOnClickListener(new View.OnClickListener() {
	@Override
	public void onClick(View v) {
	startActivity(new Intent(SignIn.this, SignUp.class));
	}
	});
	signIn.setOnClickListener(new View.OnClickListener() {
	@Override
	public void onClick(View v) {
	sigInUser();
	}
	});
	}
	private void sigInUser() {
	String emailText = email.getText().toString().trim();
	String passwordText = password.getText().toString().trim();
	firebaseAuth.signInWithEmailAndPassword(emailText, passwordText)
	.addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
	@Override
	public void onComplete(@NonNull Task<AuthResult> task) {
	if (task.isSuccessful()) {
	Toast.makeText(SignIn.this, "Authentication success.",
	Toast.LENGTH_SHORT).show();
	} else {
	Toast.makeText(SignIn.this, "Authentication failed.",
	Toast.LENGTH_SHORT).show();
	}
	}
	});
	}
	}

view raw SiginIn.java hosted with ❤ by GitHub

Once, done you can view the Toast to see whether it works or not.
When you launch the app, you have to enter email and password every time to reduce that work, you can do the following in the first activity in your app, in my case, it is SignIn.java

	// pu this inside the class
	@Override
	protected void onStart() {
	super.onStart();
	FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
	if(user != null) {
	//if user is authenticated give him access to the app
	}
	}

view raw inside hosted with ❤ by GitHub

If you have any doubts, please comment in the section below.