Zero to App: Develop with Firebase (for Android - Google I/O 2016)

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.google.firebase.zerotoapp.MainActivity">

    <RelativeLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/header"
        android:gravity="end">

        <ImageView
            android:layout_width="36dp"
            android:layout_height="36dp"
            android:background="@drawable/ic_account_box_black_24dp"
            android:id="@+id/userIcon"
            android:foregroundGravity="center"
            android:layout_alignParentStart="true"
            android:layout_alignParentLeft="true" />

        <TextView
            android:layout_width="141dp"
            android:layout_height="wrap_content"
            android:id="@+id/usernameTxt"
            android:layout_toRightOf="@+id/userIcon"
            android:layout_alignTop="@+id/userIcon"
            android:layout_alignBottom="@+id/userIcon"
            android:gravity="center_vertical"
            tools:text="Username"
            android:layout_weight="0" />

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Sign in"
            android:id="@+id/loginBtn"
            android:layout_alignParentEnd="true"
            android:layout_alignParentRight="true" />
        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Sign out"
            android:id="@+id/logoutBtn"
            android:layout_alignParentEnd="true"
            android:layout_alignParentRight="true" />
    </RelativeLayout>

    <android.support.v7.widget.RecyclerView
        android:id="@+id/messagesList"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        tools:listitem="@android:layout/two_line_list_item"
        android:layout_above="@+id/footer"
        android:layout_below="@+id/header" />

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:id="@+id/footer">

        <ImageButton
            android:layout_width="36dp"
            android:layout_height="36dp"
            android:id="@+id/imageBtn"
            android:background="@android:drawable/ic_menu_gallery" />

        <EditText
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/messageTxt"
            android:layout_gravity="bottom"
            android:layout_weight="1"
            android:inputType="textShortMessage|textAutoCorrect" />

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Send"
            android:id="@+id/sendBtn"
            android:layout_gravity="bottom" />
    </LinearLayout>
</RelativeLayout>

build.gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 24
    buildToolsVersion '24'

    defaultConfig {
        applicationId "com.google.firebase.zerotoapp"
        minSdkVersion 16
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:24.0.0'
    compile 'com.android.support:design:24.0.0'
    compile 'com.android.support:recyclerview-v7:24.0.0'
    compile 'com.google.firebase:firebase-database:9.2.1'
    compile 'com.google.firebase:firebase-auth:9.2.1'
    compile 'com.google.firebase:firebase-storage:9.2.1'
    compile 'com.github.bumptech.glide:glide:3.7.0'
    compile 'com.firebaseui:firebase-ui-auth:0.4.3'
}
apply plugin: 'com.google.gms.google-services'

ChatMessage.java

package com.google.firebase.zerotoapp;

public class ChatMessage {
    public String name;
    public String message;

    public ChatMessage() {
    }

    public ChatMessage(String name, String message) {
        this.name = name;
        this.message = message;
    }
}

ChatMessageAdapter.java

package com.google.firebase.zerotoapp;

import android.app.Activity;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.ViewGroup;

import java.util.ArrayList;
import java.util.List;

public class ChatMessageAdapter extends RecyclerView.Adapter<ChatMessageViewHolder> {
    private static final String TAG = "ChatMessageAdapter";
    private final Activity activity;
    List<ChatMessage> messages = new ArrayList<>();

    public ChatMessageAdapter(Activity activity) {
        this.activity = activity;
    }

    public void addMessage(ChatMessage chat) {
        messages.add(chat);
        notifyItemInserted(messages.size());
    }


    @Override
    public ChatMessageViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        return new ChatMessageViewHolder(activity, activity.getLayoutInflater().inflate(android.R.layout.two_line_list_item, parent, false));
    }

    @Override
    public void onBindViewHolder(ChatMessageViewHolder holder, int position) {
        holder.bind(messages.get(position));
    }

    @Override
    public int getItemCount() {
        return messages.size();
    }
}

ChatMessageViewHolder.java

package com.google.firebase.zerotoapp;

import android.app.Activity;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import com.bumptech.glide.Glide;

public class ChatMessageViewHolder extends RecyclerView.ViewHolder {
    private static final String TAG = "ChatMessageViewHolder";
    private final Activity activity;

    TextView name, message;
    ImageView image;

    public ChatMessageViewHolder(Activity activity, View itemView) {
        super(itemView);
        this.activity = activity;
        name = (TextView) itemView.findViewById(android.R.id.text1);
        message = (TextView) itemView.findViewById(android.R.id.text2);
        image= new ImageView(activity);
        ((ViewGroup)itemView).addView(image);

    }

    public void bind(ChatMessage chat) {
        name.setText(chat.name);
        if (chat.message.startsWith("https://firebasestorage.googleapis.com/") || chat.message.startsWith("content://")) {
            message.setVisibility(View.INVISIBLE);
            image.setVisibility(View.VISIBLE);
            Glide.with(activity)
                    .load(chat.message)
                    .into(image);
        }
        else {
            message.setVisibility(View.VISIBLE);
            image.setVisibility(View.GONE);
            message.setText(chat.message);
        }
    }
}

LoginDialog.java

package com.google.firebase.zerotoapp;

import android.app.Activity;
import android.content.DialogInterface;
import android.support.v7.app.AlertDialog;
import android.text.InputType;
import android.widget.EditText;
import android.widget.LinearLayout;

import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.FirebaseApp;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;

import java.util.ArrayList;
import java.util.List;

public class LoginDialog {
    private static final String TAG = "LoginDialog";

    static List<OnSuccessListener<EmailPasswordResult>> callbacks = new ArrayList<>();

    public static void onCredentials(final OnSuccessListener<EmailPasswordResult> callback) {
        callbacks.add(callback);
    }

    public static class EmailPasswordResult {
        public String email;
        public String password;

        public EmailPasswordResult() {
        }

        public EmailPasswordResult(String email, String password) {
            this.email = email;
            this.password = password;
        }
    }

    public static void showLoginPrompt(final Activity activity, final FirebaseApp app) {
        showLoginPrompt(activity, app, null);
    }
    public static void showLoginPrompt(final Activity activity, final FirebaseApp app, final OnSuccessListener<EmailPasswordResult> callback) {
        AlertDialog.Builder builder = new AlertDialog.Builder(activity);
        builder.setTitle("What's your username");

        LinearLayout parent = new LinearLayout(activity);
        parent.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT));
        parent.setOrientation(LinearLayout.VERTICAL);

        final EditText email = new EditText(activity);
        email.setInputType(InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_VARIATION_EMAIL_ADDRESS);
        email.setHint("User name");
        parent.addView(email);

        final EditText password = new EditText(activity);
        password.setInputType(InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_VARIATION_PASSWORD);
        password.setHint("Password");
        parent.addView(password);

        builder.setView(parent);

        builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                FirebaseAuth.getInstance(app).createUserWithEmailAndPassword(email.getText().toString(), password.getText().toString())
                        .addOnCompleteListener(activity, new OnCompleteListener<AuthResult>() {
                            public void onComplete(Task<AuthResult> task) {
                                EmailPasswordResult result = new EmailPasswordResult(email.getText().toString(), password.getText().toString());
                                if (callback != null) {
                                    callback.onSuccess(result);
                                }
                                else {
                                    for (OnSuccessListener<EmailPasswordResult> callback: callbacks){
                                        callback.onSuccess(result);
                                    }
                                }
                            }
                        });
                dialog.dismiss();
            }
        });
        builder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.cancel();
            }
        });

        builder.show();
    }
}

MainActivity.java

package com.google.firebase.zerotoapp;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.TextView;

import com.google.android.gms.tasks.OnSuccessListener;
import com.google.firebase.FirebaseApp;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.storage.FirebaseStorage;
import com.google.firebase.storage.StorageReference;

public class MainActivity extends AppCompatActivity {
    private static final String TAG = "MainActivity";

    static final int RC_PHOTO_PICKER = 1;

    private Button sendBtn;
    private EditText messageTxt;
    private RecyclerView messagesList;
    private ChatMessageAdapter adapter;
    private ImageButton imageBtn;
    private TextView usernameTxt;
    private View loginBtn;
    private View logoutBtn;

    private FirebaseApp app;
    private FirebaseDatabase database;
    private FirebaseAuth auth;
    private FirebaseStorage storage;

    private DatabaseReference databaseRef;
    private StorageReference storageRef;

    private String username;

    private void setUsername(String username) {
        Log.d(TAG, "setUsername("+String.valueOf(username)+")");
        if (username == null) {
            username = "Android";
        }
        boolean isLoggedIn = !username.equals("Android");
        this.username = username;
        this.usernameTxt.setText(username);
        this.logoutBtn.setVisibility(isLoggedIn ? View.VISIBLE : View.GONE);
        this.loginBtn .setVisibility(isLoggedIn ? View.GONE    : View.VISIBLE);
    }

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

        sendBtn = (Button) findViewById(R.id.sendBtn);
        messageTxt = (EditText) findViewById(R.id.messageTxt);
        messagesList = (RecyclerView) findViewById(R.id.messagesList);
        imageBtn = (ImageButton) findViewById(R.id.imageBtn);
        loginBtn = findViewById(R.id.loginBtn);
        logoutBtn = findViewById(R.id.logoutBtn);
        usernameTxt = (TextView) findViewById(R.id.usernameTxt);
        setUsername("Android");

        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        messagesList.setHasFixedSize(false);
        messagesList.setLayoutManager(layoutManager);

        // Show an image picker when the user wants to upload an imasge
        imageBtn.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
                intent.setType("image/jpeg");
                intent.putExtra(Intent.EXTRA_LOCAL_ONLY, true);
                startActivityForResult(Intent.createChooser(intent, "Complete action using"), RC_PHOTO_PICKER);
            }
        });
        // Show a popup when the user asks to sign in
        loginBtn.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                LoginDialog.showLoginPrompt(MainActivity.this, app);
            }
        });
        // Allow the user to sign out
        logoutBtn.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                auth.signOut();
            }
        });

        adapter = new ChatMessageAdapter(this);
        messagesList.setAdapter(adapter);
        adapter.registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {
            public void onItemRangeInserted(int positionStart, int itemCount) {
                messagesList.smoothScrollToPosition(adapter.getItemCount());
            }
        });
        
        // Get the Firebase app and all primitives we'll use
        app = FirebaseApp.getInstance();
        database = FirebaseDatabase.getInstance(app);
        auth = FirebaseAuth.getInstance(app);
        storage = FirebaseStorage.getInstance(app);
        
        // Get a reference to our chat "room" in the database
        databaseRef = database.getReference("chat");

        sendBtn.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                ChatMessage chat = new ChatMessage(username, messageTxt.getText().toString());
                // Push the chat message to the database
                databaseRef.push().setValue(chat);
                messageTxt.setText("");
            }
        });
        // Listen for when child nodes get added to the collection
        databaseRef.addChildEventListener(new ChildEventListener() {
            public void onChildAdded(DataSnapshot snapshot, String s) {
                // Get the chat message from the snapshot and add it to the UI
                ChatMessage chat = snapshot.getValue(ChatMessage.class);
                adapter.addMessage(chat);
            }

            public void onChildChanged(DataSnapshot dataSnapshot, String s) { }
            public void onChildRemoved(DataSnapshot dataSnapshot) { }
            public void onChildMoved(DataSnapshot dataSnapshot, String s) { }
            public void onCancelled(DatabaseError databaseError) { }
        });
        
        // When the user has entered credentials in the login dialog
        LoginDialog.onCredentials(new OnSuccessListener<LoginDialog.EmailPasswordResult>() {
            public void onSuccess(LoginDialog.EmailPasswordResult result) {
                // Sign the user in with the email address and password they entered
                auth.signInWithEmailAndPassword(result.email, result.password);
            }
        });

        // When the user signs in or out, update the username we keep for them
        auth.addAuthStateListener(new FirebaseAuth.AuthStateListener() {
            public void onAuthStateChanged(FirebaseAuth firebaseAuth) {
                if (firebaseAuth.getCurrentUser() != null) {
                    // User signed in, set their email address as the user name
                    setUsername(firebaseAuth.getCurrentUser().getEmail());
                }
                else {
                    // User signed out, set a default username
                    setUsername("Android");
                }
            }
        });
    }

    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == RC_PHOTO_PICKER && resultCode == RESULT_OK) {
            Uri selectedImageUri = data.getData();

            // Get a reference to the location where we'll store our photos
            storageRef = storage.getReference("chat_photos");
            // Get a reference to store file at chat_photos/<FILENAME>
            final StorageReference photoRef = storageRef.child(selectedImageUri.getLastPathSegment());

            // Upload file to Firebase Storage
            photoRef.putFile(selectedImageUri)
                    .addOnSuccessListener(this, new OnSuccessListener<UploadTask.TaskSnapshot>() {
                        public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
                            // When the image has successfully uploaded, we get its download URL
                            Uri downloadUrl = taskSnapshot.getDownloadUrl();
                            // Set the download URL to the message box, so that the user can send it to the database
                            messageTxt.setText(downloadUrl.toString());
                        }
                    });
        }
    }
}