Setting up Firebase for your project

  1. Create your new project in Android Studio.
  2. Go to browser and log in with your Google account. Go to Firebase Console. Add a project, give a name.
  3. Under Project Overview, click on the button to add Android app. Firebase console will prompt you to enter the package name of your app. Download the google-services.json file and add it to your projects app folder.

in your project level build.gradle file, add this line under dependencies

classpath 'com.google.gms:google-services:4.0.1'

In your app level build.gradle file, add this line under dependencies

implementation 'com.google.firebase:firebase-core:16.0.1'
implementation 'com.google.firebase:firebase-auth:16.1.0'

and at the bottom add this line

apply plugin: 'com.google.gms.google-services'

Firebase is now integrated into your project.

Make sure to add INTERNET permission to your AndroidManifest.xml

<uses-permission android:name="android.permission.INTERNET" />

Enabling authentication

Go to your project dashboard, and in the left panel, under Develop, select Authentication.

Screenshot 2019-03-07 at 10.31.12 AM.png

Under Sign-In methods, enable Email/Password, and save.

Registration screen

Create XML layout

act_register.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
    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:fitsSystemWindows="true">

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:background="@color/colorPrimaryDark"
        android:gravity="center"
        android:orientation="vertical"
        android:padding="32dp">


        <ImageView
            android:layout_width="100dp"
            android:layout_height="100dp"
            android:layout_gravity="center_horizontal"
            android:layout_marginBottom="30dp"
            android:src="@mipmap/ic_launcher" />

        <android.support.design.widget.TextInputLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <EditText
                android:id="@+id/email"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:hint="Email"
                android:inputType="textEmailAddress"
                android:maxLines="1"
                android:singleLine="true"
                android:textColor="@android:color/white" />

        </android.support.design.widget.TextInputLayout>

        <android.support.design.widget.TextInputLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <EditText
                android:id="@+id/password"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:focusableInTouchMode="true"
                android:hint="Password"
                android:imeOptions="actionUnspecified"
                android:inputType="textPassword"
                android:maxLines="1"
                android:singleLine="true"
                android:textColor="@android:color/white" />

        </android.support.design.widget.TextInputLayout>

        <Button
            android:id="@+id/sign_up_button"
            style="?android:textAppearanceSmall"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="16dp"
            android:background="@color/colorAccent"
            android:text="REGISTER"
            android:textColor="@android:color/black"
            android:textStyle="bold" />

        <Button
            android:id="@+id/btn_reset_password"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="20dip"
            android:background="@null"
            android:text="Forgot Password?"
            android:textAllCaps="false"
            android:textColor="@color/colorAccent" />
        
        <Button
            android:id="@+id/sign_in_button"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="20dip"
            android:background="@null"
            android:text="Already have an account? Log in!"
            android:textAllCaps="false"
            android:textColor="@color/white"
            android:textSize="15dp" />
    </LinearLayout>

    <ProgressBar
        android:id="@+id/progressBar"
        android:layout_width="30dp"
        android:layout_height="30dp"
        android:layout_gravity="center|bottom"
        android:layout_marginBottom="20dp"
        android:visibility="gone" />
</android.support.design.widget.CoordinatorLayout>

RegisterActivity.java

public class RegisterActivity extends AppCompatActivity {

    private EditText inputEmail, inputPassword;
    private Button btnSignIn, btnSignUp, btnResetPassword;
    private ProgressBar progressBar;
    private FirebaseAuth auth;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.act_register);

        //Get Firebase auth instance
        auth = FirebaseAuth.getInstance();

        btnSignIn = (Button) findViewById(R.id.sign_in_button);
        btnSignUp = (Button) findViewById(R.id.sign_up_button);
        inputEmail = (EditText) findViewById(R.id.email);
        inputPassword = (EditText) findViewById(R.id.password);
        progressBar = (ProgressBar) findViewById(R.id.progressBar);
        btnResetPassword = (Button) findViewById(R.id.btn_reset_password);

        btnResetPassword.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(RegisterActivity.this, ResetPasswordActivity.class));
            }
        });

        btnSignIn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                finish();
                startActivity(new Intent(RegisterActivity.this, LoginActivity.class));
            }
        });

        btnSignUp.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                String email = inputEmail.getText().toString().trim();
                String password = inputPassword.getText().toString().trim();

                if (TextUtils.isEmpty(email)) {
                    Toast.makeText(getApplicationContext(), "Enter email address!", Toast.LENGTH_SHORT).show();
                    return;
                }

                if (TextUtils.isEmpty(password)) {
                    Toast.makeText(getApplicationContext(), "Enter password!", Toast.LENGTH_SHORT).show();
                    return;
                }

                if (password.length() < 6) {
                    Toast.makeText(getApplicationContext(), "Password too short, enter minimum 6 characters!", Toast.LENGTH_SHORT).show();
                    return;
                }

                progressBar.setVisibility(View.VISIBLE);
                //create user
                auth.createUserWithEmailAndPassword(email, password)
                        .addOnCompleteListener(RegisterActivity.this, new OnCompleteListener<AuthResult>() {
                            @Override
                            public void onComplete(@NonNull Task<AuthResult> task) {
                                Toast.makeText(RegisterActivity.this, "createUserWithEmail:onComplete:" + task.isSuccessful(), Toast.LENGTH_SHORT).show();
                                progressBar.setVisibility(View.GONE);

                                if (!task.isSuccessful()) {
                                    Toast.makeText(RegisterActivity.this, "Authentication failed." + task.getException(),
                                            Toast.LENGTH_SHORT).show();
                                } else {
                                    startActivity(new Intent(RegisterActivity.this, MainActivity.class));
                                    finish();
                                }
                            }
                        });

            }
        });
    }

    @Override
    protected void onResume() {
        super.onResume();
        progressBar.setVisibility(View.GONE);
    }
}

 

Login Screen

act_login.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 
    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:fitsSystemWindows="true">

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:background="@color/colorPrimary"
        android:gravity="center"
        android:orientation="vertical"
        android:padding="32dp">


        <ImageView
            android:layout_width="100dp"
            android:layout_height="100dp"
            android:layout_gravity="center_horizontal"
            android:layout_marginBottom="30dp"
            android:src="@mipmap/ic_launcher" />

        <android.support.design.widget.TextInputLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <EditText
                android:id="@+id/email"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginBottom="10dp"
                android:hint="Email"
                android:inputType="textEmailAddress"
                android:textColor="@android:color/white"
                android:textColorHint="@android:color/white" />
        </android.support.design.widget.TextInputLayout>

        <android.support.design.widget.TextInputLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <EditText
                android:id="@+id/password"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_marginBottom="10dp"
                android:hint="Password"
                android:inputType="textPassword"
                android:textColor="@android:color/white"
                android:textColorHint="@android:color/white" />
        </android.support.design.widget.TextInputLayout>

        <Button
            android:id="@+id/btn_login"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="20dip"
            android:background="@color/colorAccent"
            android:text="LOGIN"
            android:textColor="@android:color/black" />

        <Button
            android:id="@+id/btn_reset_password"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="20dip"
            android:background="@null"
            android:text="Forgot password"
            android:textAllCaps="false"
            android:textColor="@color/colorAccent" />

        <Button
            android:id="@+id/btn_signup"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="20dip"
            android:background="@null"
            android:text="No account? Register"
            android:textAllCaps="false"
            android:textSize="15dp" />
    </LinearLayout>

    <ProgressBar
        android:id="@+id/progressBar"
        android:layout_width="30dp"
        android:layout_height="30dp"
        android:layout_gravity="center|bottom"
        android:layout_marginBottom="20dp"
        android:visibility="gone" />
</android.support.design.widget.CoordinatorLayout>

LoginActivity.java

public class LoginActivity extends AppCompatActivity {

    private EditText inputEmail, inputPassword;
    private FirebaseAuth auth;
    private ProgressBar progressBar;
    private Button btnSignup, btnLogin, btnReset;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        //Get Firebase auth instance
        auth = FirebaseAuth.getInstance();

        if (auth.getCurrentUser() != null) {
            startActivity(new Intent(LoginActivity.this, MainActivity.class));
            finish();
        }

        // set the view now
        setContentView(R.layout.act_login);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        inputEmail = (EditText) findViewById(R.id.email);
        inputPassword = (EditText) findViewById(R.id.password);
        progressBar = (ProgressBar) findViewById(R.id.progressBar);
        btnSignup = (Button) findViewById(R.id.btn_signup);
        btnLogin = (Button) findViewById(R.id.btn_login);
        btnReset = (Button) findViewById(R.id.btn_reset_password);

        //Get Firebase auth instance
        auth = FirebaseAuth.getInstance();

        btnSignup.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(LoginActivity.this, RegisterActivity.class));
                finish();
            }
        });

        btnReset.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(LoginActivity.this, ResetPasswordActivity.class));
            }
        });

        btnLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String email = inputEmail.getText().toString();
                final String password = inputPassword.getText().toString();

                if (TextUtils.isEmpty(email)) {
                    Toast.makeText(getApplicationContext(), "Enter email address!", Toast.LENGTH_SHORT).show();
                    return;
                }

                if (TextUtils.isEmpty(password)) {
                    Toast.makeText(getApplicationContext(), "Enter password!", Toast.LENGTH_SHORT).show();
                    return;
                }

                progressBar.setVisibility(View.VISIBLE);

                //authenticate user
                auth.signInWithEmailAndPassword(email, password)
                        .addOnCompleteListener(LoginActivity.this, new OnCompleteListener<AuthResult>() {
                            @Override
                            public void onComplete(@NonNull Task<AuthResult> task) {
                                // If sign in fails, display a message to the user. If sign in succeeds
                                // the auth state listener will be notified and logic to handle the
                                // signed in user can be handled in the listener.
                                progressBar.setVisibility(View.GONE);
                                if (!task.isSuccessful()) {
                                    // there was an error
                                    if (password.length() < 6) {
                                        inputPassword.setError("Password too short, enter minimum 6 characters!");
                                    } else {
                                        Toast.makeText(LoginActivity.this, "Authentication failed, check your email and password or sign up", Toast.LENGTH_LONG).show();
                                    }
                                } else {
                                    Intent intent = new Intent(LoginActivity.this, MainActivity.class);
                                    startActivity(intent);
                                    finish();
                                }
                            }
                        });
            }
        });
    }
}

 

Forgot Password

act_reset_pwd.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 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:layout_gravity="center"
    android:background="@color/colorPrimary"
    android:fitsSystemWindows="true">

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="30dp"
        android:gravity="center"
        android:orientation="vertical"
        android:padding="32dp">


        <ImageView
            android:layout_width="100dp"
            android:layout_height="100dp"
            android:layout_gravity="center_horizontal"
            android:layout_marginBottom="10dp"
            android:src="@mipmap/ic_launcher" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal"
            android:padding="10dp"
            android:text="Forgot Password?"
            android:textColor="@android:color/white"
            android:textSize="20dp" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginBottom="10dp"
            android:gravity="center_horizontal"
            android:padding="16dp"
            android:text="We just need your registered Email Id to sent you password reset instructions."
            android:textColor="@android:color/white"
            android:textSize="14dp" />

        <android.support.design.widget.TextInputLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <EditText
                android:id="@+id/email"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginBottom="10dp"
                android:layout_marginTop="20dp"
                android:hint="Enter your email"
                android:inputType="textEmailAddress"
                android:textColor="@android:color/white"
                android:textColorHint="@android:color/white" />
        </android.support.design.widget.TextInputLayout>
        
        <Button
            android:id="@+id/btn_reset_password"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="20dip"
            android:background="@color/colorAccent"
            android:text="RESET PASSWORD"
            android:textColor="@android:color/black" />

        <Button
            android:id="@+id/btn_back"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dp"
            android:background="@null"
            android:text="BACK"
            android:textColor="@color/colorAccent" />

    </LinearLayout>

    <ProgressBar
        android:id="@+id/progressBar"
        android:layout_width="30dp"
        android:layout_height="30dp"
        android:layout_gravity="center|bottom"
        android:layout_marginBottom="20dp"
        android:visibility="gone" />
</android.support.design.widget.CoordinatorLayout>

ResetPasswordActivity.java

public class ResetPasswordActivity extends AppCompatActivity {

    private EditText inputEmail;
    private Button btnReset, btnBack;
    private FirebaseAuth auth;
    private ProgressBar progressBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.act_reset_pwd);

        inputEmail = (EditText) findViewById(R.id.email);
        btnReset = (Button) findViewById(R.id.btn_reset_password);
        btnBack = (Button) findViewById(R.id.btn_back);
        progressBar = (ProgressBar) findViewById(R.id.progressBar);

        auth = FirebaseAuth.getInstance();

        btnBack.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                finish();
            }
        });

        btnReset.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                String email = inputEmail.getText().toString().trim();

                if (TextUtils.isEmpty(email)) {
                    Toast.makeText(getApplication(), "Enter your registered email id", Toast.LENGTH_SHORT).show();
                    return;
                }

                progressBar.setVisibility(View.VISIBLE);
                auth.sendPasswordResetEmail(email)
                        .addOnCompleteListener(new OnCompleteListener<Void>() {
                            @Override
                            public void onComplete(@NonNull Task<Void> task) {
                                if (task.isSuccessful()) {
                                    Toast.makeText(ResetPasswordActivity.this, "We have sent you instructions to reset your password!", Toast.LENGTH_SHORT).show();
                                } else {
                                    Toast.makeText(ResetPasswordActivity.this, "Failed to send reset email!", Toast.LENGTH_SHORT).show();
                                }
                                progressBar.setVisibility(View.GONE);
                            }
                        });
            }
        });
    }
}

 


Check if a user is logged in

private FirebaseAuth mAuth;
mAuth = FirebaseAuth.getInstance();
FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
if (user != null) {
    //user is logged in
} else {
    //not logged in
    goToLogin();
}

Get user details

FirebaseUser currentUser = mAuth.getCurrentUser();
if (currentUser != null) {
    //getting display name and email
    String name = currentUser.getDisplayName();
    String email = currentUser.getEmail();
    
    //getting display picture if available
    Picasso.with(this).load(currentUser.getPhotoUrl()).into(userdpImageView);
}

Logging out

public void signOut() {
    auth.signOut();

    FirebaseAuth.AuthStateListener authListener = new FirebaseAuth.AuthStateListener() {
        @Override
        public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
            FirebaseUser user = firebaseAuth.getCurrentUser();
            if (user == null) {
                // user auth state is changed - user is null
                // launch login activity
                startActivity(new Intent(MainActivity.this, LoginActivity.class));
                finish();
            }
        }
    };
}

Previews & screenshots coming soon.