public class ChatSDKLoginActivity extends ChatSDKAbstractLoginActivity implements View.OnClickListener{

private static final String TAG = ChatSDKLoginActivity.class.getSimpleName();
private static boolean DEBUG = Debug.LoginActivity;

private Button btnLogin, btnReg, btnAnon, btnTwitter;
private ImageView appIconImage;

@Override
protected void onCreate(Bundle savedInstanceState) {
    enableFacebookIntegration(getNetworkAdapter().facebookEnabled());
    super.onCreate(savedInstanceState);
    setContentView(R.layout.chat_sdk_activty_login);

    setExitOnBackPressed(true);

    View view = findViewById(R.id.chat_sdk_root_view);

    setupTouchUIToDismissKeyboard(view);

    initViews();

    ((TextView) findViewById(R.id.chat_sdk_txt_version)).setText(String.valueOf(BuildConfig.VERSION_NAME));
}

@Override
protected void initViews(){
    super.initViews();
    facebookLogin.setCompoundDrawablesWithIntrinsicBounds(0,0,0,0);
    facebookLogin.setBackgroundResource(R.drawable.ic_facebook);

    if (integratedWithFacebook)
    {

        facebookLogin.setReadPermissions(Arrays.asList("email", "user_friends"));
    }

    btnLogin = (Button) findViewById(R.id.chat_sdk_btn_login);
    btnAnon = (Button) findViewById(R.id.chat_sdk_btn_anon_login);
    btnTwitter = (Button) findViewById(R.id.chat_sdk_btn_twitter_login);
    btnReg = (Button) findViewById(R.id.chat_sdk_btn_register);
    etEmail = (EditText) findViewById(R.id.chat_sdk_et_mail);
    etPass = (EditText) findViewById(R.id.chat_sdk_et_password);

    appIconImage = (ImageView) findViewById(R.id.app_icon);

    appIconImage.post(new Runnable() {
        @Override
        public void run() {
            appIconImage.setVisibility(View.VISIBLE);
        }
    });
}

private void initListeners(){
    /* Registering listeners.*/
    btnLogin.setOnClickListener(this);
    btnReg.setOnClickListener(this);
    btnAnon.setOnClickListener(this);
    btnTwitter.setOnClickListener(this);

    etPass.setOnEditorActionListener(new TextView.OnEditorActionListener() {
        @Override
        public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
            if (actionId == EditorInfo.IME_ACTION_DONE){
                btnLogin.callOnClick();
            }
            return false;
        }
    });
}
@Override
protected void onResume() {
    super.onResume();

    initListeners();
}

/* Dismiss dialog and open main activity.*/
@Override
protected void afterLogin(){
    super.afterLogin();

    // Updating the version name.
    BUser curUser = getNetworkAdapter().currentUserModel();

    String version = BDefines.BAppVersion,
            metaVersion = curUser.metaStringForKey(BDefines.Keys.BVersion);

    if (StringUtils.isNotEmpty(version))
    {
        if (StringUtils.isEmpty(metaVersion) || !metaVersion.equals(version))
        {
            curUser.setMetadataString(BDefines.Keys.BVersion, version);
        }

        DaoCore.updateEntity(curUser);
    }

    startMainActivity();
}

@Override
public void onClick(View v) {
    int i = v.getId();

    if (i == R.id.chat_sdk_btn_login) {
        passwordLogin();
    }
    else if (i == R.id.chat_sdk_btn_anon_login) {
        anonymosLogin();
    }
    else if (i == R.id.chat_sdk_btn_register)
    {
        startActivity(new Intent(ChatSDKLoginActivity.this, chat_register.class));
    }

    else if (i == R.id.chat_sdk_btn_twitter_login){
        twitterLogin();
    }
}
}

public class chat_register extends AppCompatActivity implements View.OnClickListener{

//defining view objects
private EditText editTextEmail;
private EditText editTextPassword;
private Button buttonSignup;
private Button buttonSignin;

private TextView textViewSignin;

private ProgressDialog progressDialog;


//defining firebaseauth object
private FirebaseAuth firebaseAuth;

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

    firebaseAuth = FirebaseAuth.getInstance();

    //if getCurrentUser does not returns null
    if(firebaseAuth.getCurrentUser() != null){
        //that means user is already logged in
        //so close this activity
        finish();

        //and open profile activity
        startActivity(new Intent(getApplicationContext(), ChatSDKMainActivity.class));
    }

    //initializing views
    editTextEmail = (EditText) findViewById(R.id.chat_sdk_et_mail);
    editTextPassword = (EditText) findViewById(R.id.chat_sdk_et_password);

    buttonSignin = (Button) findViewById(R.id.chat_sdk_btn_login);

    buttonSignup = (Button) findViewById(R.id.chat_sdk_btn_register);

    //attaching listener to button
    buttonSignup.setOnClickListener(this);
    buttonSignin.setOnClickListener(this);
}

private void registerUser(){

    //getting email and password from edit texts
    String email = editTextEmail.getText().toString().trim();
    String password  = editTextPassword.getText().toString().trim();

    //checking if email and passwords are empty
    if(TextUtils.isEmpty(email)){
        Toast.makeText(this,"Please enter email",Toast.LENGTH_LONG).show();
        return;
    }

    if(TextUtils.isEmpty(password)){
        Toast.makeText(this,"Please enter password",Toast.LENGTH_LONG).show();
        return;
    }

    //if the email and password are not empty
    //displaying a progress dialog

    progressDialog.setMessage("Registering Please Wait...");
    progressDialog.show();

    //creating a new user
    firebaseAuth.createUserWithEmailAndPassword(email, password)
            .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    //checking if success
                    if(task.isSuccessful()){
                        finish();
                        startActivity(new Intent(getApplicationContext(), ChatSDKMainActivity.class));
                    }
                    progressDialog.dismiss();
                }
            });

}

@Override
public void onClick(View view) {

    if(view == buttonSignup){
        registerUser();
    }

    if(view == textViewSignin){
        //open login activity when user taps on the already registered textview
        startActivity(new Intent(this, ChatSDKLoginActivity.class));
    }

}
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/white"
android:id="@+id/chat_sdk_register_view"
tools:context="com.braunster.chatsdk.activities.chat_register">

<LinearLayout
    android:layout_centerVertical="true"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">


    <ImageView
        android:layout_width="160dp"
        android:layout_height="160dp"
        android:layout_centerHorizontal="true"
        android:src="@drawable/ic_launcher_big"
        android:id="@+id/app_icon"
        android:visibility="invisible"
        android:layout_gravity="center"
        android:layout_alignParentTop="true"
        />

    <EditText
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:inputType="textEmailAddress"
    android:ems="10"
    android:nextFocusDown="@+id/chat_sdk_et_password"
    android:id="@+id/chat_sdk_et_mail"
    android:gravity="center"
    android:layout_above="@id/chat_sdk_et_password"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:hint="@string/email" />

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:inputType="textPassword"
        android:ems="10"
        android:id="@+id/chat_sdk_et_password"
        android:layout_alignLeft="@+id/chat_sdk_et_mail"
        android:layout_alignStart="@+id/chat_sdk_et_mail"
        android:hint="@string/password"
        android:gravity="center"/>


    <Button
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="@string/register"
        style="@style/LoginButtonsStyle"
        android:background="@drawable/chat_sdk_register_button_selector"
        android:id="@+id/chat_sdk_btn_register"
        android:layout_weight="1"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Already Registered? login"
        style="@style/LoginButtonsStyle"
        android:background="@drawable/chat_sdk_login_button_selector"
        android:id="@+id/chat_sdk_btn_login"
        android:layout_weight="1"/>

</LinearLayout>

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>

<!-- For image capturing -->
<uses-feature
    android:name="android.hardware.camera"
    android:required="false" />

<!-- For saving images to the internal and external storage. -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

<!-- For Google Maps. -->
<uses-feature
    android:glEsVersion="0x00020000"
    android:required="true" />

<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

<!-- Parse -->
<!--
<uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="android.permission.VIBRATE"/>
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.GET_ACCOUNTS"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
-->


<!-- Backendless -->
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.GET_ACCOUNTS" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="android.permission.VIBRATE" />
<uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" />
<uses-permission android:name="com.braunster.chatsdk.permission.C2D_MESSAGE" />

<permission
    android:name="com.braunster.chatsdk.permission.C2D_MESSAGE"
    android:protectionLevel="signature" />

<!-- BugSense -->
<!-- <uses-permission android:name="android.permission.READ_LOGS" /> -->
<application
    android:allowBackup="true"
    android:label="@string/app_name"
    android:largeHeap="true">
    <meta-data
        android:name="com.facebook.sdk.ApplicationId"
        android:value="@string/facebook_id" />

    <!-- android:theme="@android:style/Theme.NoDisplay" -->
    <activity android:name="com.facebook.LoginActivity">
        <intent-filter>
            <action android:name="android.intent.action.VIEW" />

            <category android:name="android.intent.category.DEFAULT" />
            <category android:name="android.intent.category.BROWSABLE" />

            <data
                android:host="http"
                android:scheme="androidchatsdktwitter.com" />
        </intent-filter>
    </activity>
    <activity
        android:name=".activities.ChatSDKThreadDetailsActivity"
        android:theme="@style/ChatSDKSlidingTransactionTheme"
        android:windowSoftInputMode="stateHidden" />
    <activity
        android:name=".activities.ChatSDKChatActivity"
        android:launchMode="singleTop"
        android:theme="@style/ChatSDKSlidingTransactionTheme"
        android:windowSoftInputMode="stateHidden|adjustResize" />
    <activity
        android:name=".activities.ChatSDKMainActivity"
        android:launchMode="singleTask"
        android:theme="@style/ChatSDKTheme"
        android:windowSoftInputMode="stateHidden|adjustResize" />

    <activity
        android:name=".activities.ChatSDKPickFriendsActivity"
        android:theme="@style/ChatSDKSlidingTransactionTheme"
        android:windowSoftInputMode="stateHidden" />
    <activity
        android:name=".activities.ChatSDKLocationActivity"
        android:theme="@style/ChatSDKTheme" />

    <activity
        android:name=".activities.chat_register"
        android:theme="@style/ChatSDKTheme" />

    <activity
        android:name=".activities.ChatSDKSearchActivity"
        android:theme="@style/ChatSDKTheme">
        <intent-filter>
            <action android:name="com.braunster.chatsdk.ACTION_SEARCH_AND_ADD_USERS" />

            <category android:name="android.intent.category.DEFAULT" />
        </intent-filter>
    </activity>
    <activity
        android:name=".activities.ChatSDKEditProfileActivity"
        android:theme="@style/ChatSDKSlidingTransactionTheme"
        android:windowSoftInputMode="stateHidden|adjustPan" />
    <activity
        android:name=".activities.ChatSDKShareWithContactsActivity"
        android:noHistory="true"
        android:theme="@style/ChatSDKTheme">
        <intent-filter>
            <action android:name="android.intent.action.SEND" />

            <category android:name="android.intent.category.DEFAULT" />

            <data android:mimeType="image/*" />
        </intent-filter>
        <intent-filter>
            <action android:name="android.intent.action.SEND" />

            <category android:name="android.intent.category.DEFAULT" />

            <data android:mimeType="text/plain" />
        </intent-filter>
    </activity>

    <!-- Crop image -->
    <activity android:name="com.soundcloud.android.crop.CropImageActivity" />

    <!-- Google Maps Metadata -->
    <meta-data
        android:name="com.google.android.gms.version"
        android:value="@integer/google_play_services_version" />

</application>