Google Integration

Dependencies

    implementation 'com.google.android.gms:play-services-auth:17.0.0'
    implementation 'com.google.firebase:firebase-auth:18.1.0'
    implementation 'com.google.firebase:firebase-core:17.0.1'
    implementation 'com.google.code.gson:gson:2.8.5'


 classpath 'com.google.gms:google-services:4.3.0'
 maven { url 'https://maven.google.com' }

MainActivity.java

package com.example.e_building_design;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import com.google.android.gms.auth.api.signin.GoogleSignIn;
import com.google.android.gms.auth.api.signin.GoogleSignInAccount;
import com.google.android.gms.auth.api.signin.GoogleSignInClient;
import com.google.android.gms.auth.api.signin.GoogleSignInOptions;
import com.google.android.gms.common.SignInButton;
import com.google.android.gms.common.api.ApiException;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.FirebaseApp;
import com.google.firebase.auth.AuthCredential;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.auth.GoogleAuthProvider;

import static com.google.firebase.auth.GoogleAuthProvider.*;

public class LoginActivity extends AppCompatActivity {

    protected TextView tvSignIn;
    private TextView tvSignUp;
    private Activity activity = LoginActivity.this;
    private ImageView img_google;
    private GoogleSignInClient googleSignInClient;
    private SignInButton googleSignInButton;
    private static final int RC_SIGN_IN = 234;
    //creating a GoogleSignInClient object
    GoogleSignInClient mGoogleSignInClient;

    //And also a Firebase Auth object
    FirebaseAuth mAuth;
    private static final String TAG = "LoginActivity";



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


        initView();
     


        // FirebaseApp.initializeApp(activity);
        mAuth = FirebaseAuth.getInstance();

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

        //Then we will get the GoogleSignInClient object from GoogleSignIn class
        mGoogleSignInClient = GoogleSignIn.getClient(this, gso);

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

    private void initView() {
        tvSignUp = (TextView) findViewById(R.id.tvSignUp);
        tvSignIn = (TextView) findViewById(R.id.tvSignIn);
        img_google = (ImageView) findViewById(R.id.img_google);
    }



    @Override
    protected void onStart() {
        super.onStart();

        //if the user is already signed in
        //we will close this activity
        //and take the user to profile activity
        if (mAuth.getCurrentUser() != null) {
           // finish();
          //  startActivity(new Intent(this, ProfileActivity.class));
            Toast.makeText(activity, "user is already signed in", Toast.LENGTH_SHORT).show();
        }
    }


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

        //if the requestCode is the Google Sign In code that we defined at starting
        if (requestCode == RC_SIGN_IN) {

            //Getting the GoogleSignIn Task
            Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(data);
            try {
                //Google Sign In was successful, authenticate with Firebase
                GoogleSignInAccount account = task.getResult(ApiException.class);

                //authenticating with firebase
                firebaseAuthWithGoogle(account);
            } catch (ApiException e) {
                Toast.makeText(activity, e.getMessage(), Toast.LENGTH_SHORT).show();
            }
        }
    }

    private void firebaseAuthWithGoogle(GoogleSignInAccount acct) {
        Log.d(TAG, "firebaseAuthWithGoogle:" + acct.getId());

        //getting the auth credential
        AuthCredential credential = getCredential(acct.getIdToken(), null);

        //Now using firebase we are signing in the user here
        mAuth.signInWithCredential(credential)
                .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        if (task.isSuccessful()) {
                            Log.d(TAG, "signInWithCredential:success");
                            FirebaseUser user = mAuth.getCurrentUser();

                            Log.e("Username=", user.getDisplayName());
                            Log.e("Email=", user.getEmail());
                           // Log.e("Mobile=", user.getPhoneNumber());

                            Toast.makeText(activity, "User Signed In", Toast.LENGTH_SHORT).show();
                        } else {
                            // If sign in fails, display a message to the user.
                            Log.w(TAG, "signInWithCredential:failure", task.getException());
                            Toast.makeText(activity, "Authentication failed.",
                                    Toast.LENGTH_SHORT).show();

                        }


                    }
                });
    }


    //this method is called on click
    private void signIn() {
        //getting the google signin intent
        Intent signInIntent = mGoogleSignInClient.getSignInIntent();

        //starting the activity for result
        startActivityForResult(signInIntent, RC_SIGN_IN);
    }
}