Firebase-Google-Sign-In

activity_sign_in.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              xmlns:tools="http://schemas.android.com/tools"
              android:id="@+id/main_layout"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:background="@color/blue_grey_700"
              android:orientation="vertical"
              android:weightSum="4"
              tools:context=".SignInActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="3"
        android:gravity="center_horizontal"
        android:orientation="vertical">

        <ImageView
            android:id="@+id/google_icon"
            android:layout_width="48dp"
            android:layout_height="48dp"
            android:layout_marginBottom="10dp"
            android:layout_marginTop="15dp"
            android:contentDescription="@string/desc_google_icon"
            android:src="@mipmap/googleg_color" />

        <TextView
            android:id="@+id/title_text"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginBottom="10dp"
            android:text="@string/title_text"
            android:gravity="center"
            android:textColor="@android:color/white"
            android:textSize="36sp" />

        <TextView
            android:id="@+id/status"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/signed_out"
            android:textColor="@android:color/white"
            android:textSize="14sp" />

        <TextView
            android:id="@+id/detail"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:fadeScrollbars="true"
            android:gravity="center"
            android:maxLines="5"
            android:padding="10dp"
            android:scrollbars="vertical"
            android:textColor="@android:color/white"
            android:textSize="14sp" />

        <Button
            android:id="@+id/button_optional_action"
            style="@style/Base.Widget.AppCompat.Button.Borderless.Colored"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:visibility="gone"
            tools:text="Optional Action"
            tools:visibility="visible" />

    </LinearLayout>


    <RelativeLayout
        android:layout_width="fill_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:background="@color/blue_grey_900">

        <com.google.android.gms.common.SignInButton
            android:id="@+id/sign_in_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:visibility="visible"
            tools:visibility="gone" />

        <LinearLayout
            android:id="@+id/sign_out_and_disconnect"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:orientation="horizontal"
            android:paddingLeft="16dp"
            android:paddingRight="16dp"
            android:visibility="gone"
            tools:visibility="visible">

            <Button
                android:id="@+id/sign_out_button"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:text="@string/sign_out"
                android:theme="@style/ThemeOverlay.MyDarkButton" />

            <Button
                android:id="@+id/disconnect_button"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:text="@string/disconnect"
                android:theme="@style/ThemeOverlay.MyDarkButton" />
        </LinearLayout>

    </RelativeLayout>

</LinearLayout>

SignInActivity.java

package com.tabian.firebasegooglesignin;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.TextView;

import com.google.android.gms.auth.api.Auth;
import com.google.android.gms.auth.api.signin.GoogleSignInAccount;
import com.google.android.gms.auth.api.signin.GoogleSignInOptions;
import com.google.android.gms.auth.api.signin.GoogleSignInResult;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.SignInButton;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.common.api.OptionalPendingResult;
import com.google.android.gms.common.api.ResultCallback;
import com.google.android.gms.common.api.Status;

/**
 * Activity to demonstrate basic retrieval of the Google user's ID, email address, and basic
 * profile.
 */
public class SignInActivity extends AppCompatActivity implements
        GoogleApiClient.OnConnectionFailedListener,
        View.OnClickListener {

    private static final String TAG = "SignInActivity";
    private static final int RC_SIGN_IN = 9001;

    private GoogleApiClient mGoogleApiClient;
    private TextView mStatusTextView;
    private ProgressDialog mProgressDialog;

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

        // Views
        mStatusTextView = (TextView) findViewById(R.id.status);

        // Button listeners
        findViewById(R.id.sign_in_button).setOnClickListener(this);
        findViewById(R.id.sign_out_button).setOnClickListener(this);
        findViewById(R.id.disconnect_button).setOnClickListener(this);

        // [START configure_signin]
        // Configure sign-in to request the user's ID, email address, and basic
        // profile. ID and basic profile are included in DEFAULT_SIGN_IN.
        GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                .requestEmail()
                .build();
        // [END configure_signin]

        // [START build_client]
        // Build a GoogleApiClient with access to the Google Sign-In API and the
        // options specified by gso.
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .enableAutoManage(this /* FragmentActivity */, this /* OnConnectionFailedListener */)
                .addApi(Auth.GOOGLE_SIGN_IN_API, gso)
                .build();
        // [END build_client]

        // [START customize_button]
        // Set the dimensions of the sign-in button.
        SignInButton signInButton = (SignInButton) findViewById(R.id.sign_in_button);
        signInButton.setSize(SignInButton.SIZE_STANDARD);
        // [END customize_button]
    }

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

        OptionalPendingResult<GoogleSignInResult> opr = Auth.GoogleSignInApi.silentSignIn(mGoogleApiClient);
        if (opr.isDone()) {
            // If the user's cached credentials are valid, the OptionalPendingResult will be "done"
            // and the GoogleSignInResult will be available instantly.
            Log.d(TAG, "Got cached sign-in");
            GoogleSignInResult result = opr.get();
            handleSignInResult(result);
        } else {
            // If the user has not previously signed in on this device or the sign-in has expired,
            // this asynchronous branch will attempt to sign in the user silently.  Cross-device
            // single sign-on will occur in this branch.
            showProgressDialog();
            opr.setResultCallback(new ResultCallback<GoogleSignInResult>() {
                @Override
                public void onResult(GoogleSignInResult googleSignInResult) {
                    hideProgressDialog();
                    handleSignInResult(googleSignInResult);
                }
            });
        }
    }

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

        // Result returned from launching the Intent from GoogleSignInApi.getSignInIntent(...);
        if (requestCode == RC_SIGN_IN) {
            GoogleSignInResult result = Auth.GoogleSignInApi.getSignInResultFromIntent(data);
            handleSignInResult(result);
        }
    }
    // [END onActivityResult]

    // [START handleSignInResult]
    private void handleSignInResult(GoogleSignInResult result) {
        Log.d(TAG, "handleSignInResult:" + result.isSuccess());
        if (result.isSuccess()) {
            // Signed in successfully, show authenticated UI.
            GoogleSignInAccount acct = result.getSignInAccount();
            mStatusTextView.setText(getString(R.string.signed_in_fmt, acct.getDisplayName()));
            updateUI(true);
        } else {
            // Signed out, show unauthenticated UI.
            updateUI(false);
        }
    }
    // [END handleSignInResult]

    // [START signIn]
    private void signIn() {
        Intent signInIntent = Auth.GoogleSignInApi.getSignInIntent(mGoogleApiClient);
        startActivityForResult(signInIntent, RC_SIGN_IN);
    }
    // [END signIn]

    // [START signOut]
    private void signOut() {
        Auth.GoogleSignInApi.signOut(mGoogleApiClient).setResultCallback(
                new ResultCallback<Status>() {
                    @Override
                    public void onResult(Status status) {
                        // [START_EXCLUDE]
                        updateUI(false);
                        // [END_EXCLUDE]
                    }
                });
    }
    // [END signOut]

    // [START revokeAccess]
    private void revokeAccess() {
        Auth.GoogleSignInApi.revokeAccess(mGoogleApiClient).setResultCallback(
                new ResultCallback<Status>() {
                    @Override
                    public void onResult(Status status) {
                        // [START_EXCLUDE]
                        updateUI(false);
                        // [END_EXCLUDE]
                    }
                });
    }
    // [END revokeAccess]

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {
        // An unresolvable error has occurred and Google APIs (including Sign-In) will not
        // be available.
        Log.d(TAG, "onConnectionFailed:" + connectionResult);
    }

    private void showProgressDialog() {
        if (mProgressDialog == null) {
            mProgressDialog = new ProgressDialog(this);
            mProgressDialog.setMessage(getString(R.string.loading));
            mProgressDialog.setIndeterminate(true);
        }

        mProgressDialog.show();
    }

    private void hideProgressDialog() {
        if (mProgressDialog != null && mProgressDialog.isShowing()) {
            mProgressDialog.hide();
        }
    }

    private void updateUI(boolean signedIn) {
        if (signedIn) {
            findViewById(R.id.sign_in_button).setVisibility(View.GONE);
            findViewById(R.id.sign_out_and_disconnect).setVisibility(View.VISIBLE);
        } else {
            mStatusTextView.setText(R.string.signed_out);

            findViewById(R.id.sign_in_button).setVisibility(View.VISIBLE);
            findViewById(R.id.sign_out_and_disconnect).setVisibility(View.GONE);
        }
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.sign_in_button:
                signIn();
                break;
            case R.id.sign_out_button:
                signOut();
                break;
            case R.id.disconnect_button:
                revokeAccess();
                break;
        }
    }
}