firebase chat with authentication android

different files

AndroidManifest.xml:

проверить наличие
<activity android:name=".AuthActivity" />

==========================================================================================================================

AuthActivity.java:

package com.alex.firebase;

import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.view.View;
import android.widget.Toast;

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.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthCredential;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.GoogleAuthProvider;

public class AuthActivity extends AppCompatActivity implements
        GoogleApiClient.OnConnectionFailedListener, View.OnClickListener {

    private static final int RC_SIGN_IN = 9001;
    private SignInButton mAuthButton;
    private FirebaseAuth mFirebaseAuth;
    private GoogleApiClient mGoogleApiClient;

    // Firebase instance variables

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

        mAuthButton = findViewById(R.id.auth_button);
        mAuthButton.setOnClickListener(this);

        mFirebaseAuth = FirebaseAuth.getInstance();

        GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                .requestIdToken(getString(R.string.default_web_client_id))
                .requestEmail()
                .build();
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .enableAutoManage(this /* FragmentActivity */, this /* OnConnectionFailedListener */)
                .addApi(Auth.GOOGLE_SIGN_IN_API, gso)
                .build();
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.auth_button:
                authorize();
                break;
        }
    }

    private void authorize() {
        Intent authorizeIntent = Auth.GoogleSignInApi.getSignInIntent(mGoogleApiClient);
        startActivityForResult(authorizeIntent, RC_SIGN_IN);
    }

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

        if (requestCode == RC_SIGN_IN) {
            GoogleSignInResult result = Auth.GoogleSignInApi.getSignInResultFromIntent(data);
            if (result.isSuccess()) {
                GoogleSignInAccount account = result.getSignInAccount();
                firebaseAuthWithGoogle(account);
            } else {
                // Google Sign In failed
            }
        }
    }

    private void firebaseAuthWithGoogle(GoogleSignInAccount acct) {
        AuthCredential credential = GoogleAuthProvider.getCredential(acct.getIdToken(), null);
        mFirebaseAuth.signInWithCredential(credential)
                .addOnCompleteListener(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.
                        if (!task.isSuccessful()) {
                            Toast.makeText(AuthActivity.this, "authentication failed!",
                                    Toast.LENGTH_SHORT).show();
                        } else {
                            startActivity(new Intent(AuthActivity.this, MainActivity.class));
                            finish();
                        }
                    }
                });
    }

    @Override
    public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
        Toast.makeText(this, "connection failed!", Toast.LENGTH_SHORT).show();
    }
}

==========================================================================================================================

activity_auth.xml:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/sign_in_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="40dp"
        android:gravity="center"
        android:text="Авторизуйтесь, пожалуйста"
        android:textSize="30sp"
        android:textStyle="bold" />

    <com.google.android.gms.common.SignInButton
        android:id="@+id/auth_button"
        android:layout_width="150dp"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:layout_gravity="center"
        android:visibility="visible" />

</FrameLayout>

==========================================================================================================================

menu / main_menu.xml:

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <item
        android:id="@+id/sign_out_menu"
        android:title="Sign Out"
        app:showAsAction="never" />
</menu>

==========================================================================================================================

MainActivity.java: (можно менять код целиком)

/*
что было добавлено:

1) активити теперь реализует интерфейс GoogleApiClient.OnConnectionFailedListener, требующий метод
public void onConnectionFailed(@NonNull ConnectionResult connectionResult);

2) сущности для работы с авторизацией
private GoogleApiClient mGoogleApiClient;
private FirebaseAuth mFirebaseAuth;
private FirebaseUser mFirechatUser;

3) их инициализация в onCreate

4) работа с меню для разлогинивания в методе
public boolean onOptionsItemSelected(MenuItem item);

*/

package com.alex.firebase;

import android.content.Intent;
import android.support.annotation.NonNull;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
import com.google.android.gms.auth.api.Auth;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.database.DatabaseReference;
import com.firebase.ui.database.FirebaseRecyclerAdapter;
import com.google.firebase.database.FirebaseDatabase;
import de.hdodenhof.circleimageview.CircleImageView;

import com.bumptech.glide.Glide;

public class MainActivity extends AppCompatActivity implements GoogleApiClient.OnConnectionFailedListener {

    private GoogleApiClient mGoogleApiClient;
    private FirebaseAuth mFirebaseAuth;
    private FirebaseUser mFirechatUser;

    private DatabaseReference db;
    private FirebaseRecyclerAdapter<ChatMessage, MyViewHolder> fireAdapter;
    private RecyclerView rv;
    private LinearLayoutManager lm;
    private ProgressBar progress;
    String mPhotoUrl;

    private EditText edit;
    public static final String DEFAULT_NAME = "Alex";
    private String userName;

    public static class MyViewHolder extends RecyclerView.ViewHolder {
        TextView msgTextView;
        TextView userTextView;
        CircleImageView userImageView;

        public MyViewHolder(View v) {
            super(v);
            msgTextView = itemView.findViewById(R.id.msgTextView);
            userTextView = itemView.findViewById(R.id.userTextView);
            userImageView = itemView.findViewById(R.id.userImageView);
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.main_menu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.sign_out_menu:
                mFirebaseAuth.signOut();
                Auth.GoogleSignInApi.signOut(mGoogleApiClient);
                userName = DEFAULT_NAME;
                startActivity(new Intent(this, AuthActivity.class));
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }

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

        progress = findViewById(R.id.progressBar);
        rv = findViewById(R.id.messageRecyclerView);
        lm = new LinearLayoutManager(this);
        lm.setStackFromEnd(true);
        rv.setLayoutManager(lm);

        userName = DEFAULT_NAME;
        edit = findViewById(R.id.msgEditText);

        // https://stackoverflow.com/questions/42355796/firebase-google-sign-in-will-not-work-android !!!

        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .enableAutoManage(this /* FragmentActivity */, this /* OnConnectionFailedListener */)
                .addApi(Auth.GOOGLE_SIGN_IN_API)
                .build();

        mFirebaseAuth = FirebaseAuth.getInstance();
        mFirechatUser = mFirebaseAuth.getCurrentUser();
        if (mFirechatUser == null) {
            startActivity(new Intent(this, AuthActivity.class));
            finish();
            return;
        } else {
            userName = mFirechatUser.getDisplayName();
            if (mFirechatUser.getPhotoUrl() != null) {
                mPhotoUrl = mFirechatUser.getPhotoUrl().toString();
            }
        }

        db = FirebaseDatabase.getInstance().getReference();
        fireAdapter = new FirebaseRecyclerAdapter<ChatMessage, MyViewHolder>(
                ChatMessage.class,
                R.layout.chat_message,
                MyViewHolder.class,
                db.child("messages")) {

            @Override
            protected void populateViewHolder(MyViewHolder viewHolder,
                                              ChatMessage friendlyMessage, int position) {
                progress.setVisibility(ProgressBar.INVISIBLE);
                viewHolder.msgTextView.setText(friendlyMessage.getText());
                viewHolder.userTextView.setText(friendlyMessage.getName());
                if (friendlyMessage.getPhotoUrl() == null) {
                    viewHolder.userImageView
                            .setImageDrawable(ContextCompat
                                    .getDrawable(MainActivity.this,
                                            R.drawable.ic_account_circle_black_36dp));
                } else {
                    Glide.with(MainActivity.this)
                            .load(friendlyMessage.getPhotoUrl())
                            .into(viewHolder.userImageView);
                }
            }
        };

        fireAdapter.registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {
            @Override
            public void onItemRangeInserted(int positionStart, int itemCount) {
                super.onItemRangeInserted(positionStart, itemCount);
                int friendlyMessageCount = fireAdapter.getItemCount();
                int lastVisiblePosition =
                        lm.findLastCompletelyVisibleItemPosition();

                if (lastVisiblePosition == -1 ||
                        (positionStart >= (friendlyMessageCount - 1) &&
                                lastVisiblePosition == (positionStart - 1))) {
                    rv.scrollToPosition(positionStart);
                }
            }
        });

        rv.setLayoutManager(lm);
        rv.setAdapter(fireAdapter);

        Button mSendButton = findViewById(R.id.sendButton);
        mSendButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                ChatMessage friendlyMessage = new
                        ChatMessage(edit.getText().toString(), userName, mPhotoUrl);
                db.child("messages").push().setValue(friendlyMessage);
                edit.setText("");
            }
        });
    }

    @Override
    public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
        Toast.makeText(this, "connection failed (MainActivity)", Toast.LENGTH_SHORT).show();
    }
}

==========================================================================================================================

build.gradle (Module:app):

...
implementation 'com.google.firebase:firebase-auth:16.0.2'
implementation 'com.google.android.gms:play-services-auth:15.0.1'
...