A simple Activity Written In Kotlin that shows google maps. It also uses data binding

activity_home.xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <android.support.v4.widget.DrawerLayout
        android:id="@+id/drawer_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fitsSystemWindows="true"
        tools:openDrawer="start">

        <include
            android:id="@+id/included_layout"
            layout="@layout/app_bar_home"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />

        <android.support.design.widget.NavigationView
            android:id="@+id/nav_view"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_gravity="start"
            android:fitsSystemWindows="true"
            app:headerLayout="@layout/nav_header_home"
            app:menu="@menu/activity_home_drawer" />

    </android.support.v4.widget.DrawerLayout>
</layout>

app_bar_home.xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <android.support.design.widget.CoordinatorLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.edijae.crusar.reporter.activities.HomeActivity">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:popupTheme="@style/AppTheme.PopupOverlay" />

    </android.support.design.widget.AppBarLayout>

        <android.support.constraint.ConstraintLayout
            android:id="@+id/constraint"
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <fragment
                android:id="@+id/map_fragment"
                android:name="com.google.android.gms.maps.SupportMapFragment"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintLeft_toLeftOf="parent"
                app:layout_constraintRight_toRightOf="parent"
                app:layout_constraintTop_toTopOf="parent" />

        </android.support.constraint.ConstraintLayout>
        
</android.support.design.widget.CoordinatorLayout>
</layout>

HomeActivity.kt

package com.edijae.crusar.reporter.activities

import android.arch.lifecycle.ViewModelProviders
import android.databinding.DataBindingUtil
import android.os.Bundle
import android.support.v4.view.GravityCompat
import android.support.v7.app.ActionBarDrawerToggle
import android.view.Menu
import android.view.MenuItem
import com.edijae.crusar.reporter.R
import com.edijae.crusar.reporter.controllers.LocationController
import com.edijae.crusar.reporter.databinding.ActivityHomeBinding
import com.edijae.crusar.reporter.viewmodels.HomeViewModel
import com.edijae.crusar.reporter.viewmodels.MediaViewModel
import com.google.android.gms.maps.SupportMapFragment
import kotlinx.android.synthetic.main.activity_home.*
import kotlinx.android.synthetic.main.app_bar_home.*

class HomeActivity : DaggerAppCompactActivity(){

    lateinit var homeBinding: ActivityHomeBinding
    lateinit var homeViewModel: HomeViewModel
    lateinit var mapFragment: SupportMapFragment

    override fun onCreate(savedInstanceState: Bundle?) {
        //AndroidInjection.inject(this)
        super.onCreate(savedInstanceState)
        homeBinding = DataBindingUtil.setContentView(this,
                R.layout.activity_home)
        homeViewModel = ViewModelProviders.of(this).get(HomeViewModel::class.java)
        val includedLayout = homeBinding.includedLayout
        setSupportActionBar(includedLayout?.toolbar)


        val toggle = ActionBarDrawerToggle(
                this, drawer_layout, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close)
        drawer_layout.addDrawerListener(toggle)
        toggle.syncState()

        mapFragment = supportFragmentManager.findFragmentById(R.id.map_fragment)
                as SupportMapFragment
        LocationController(mapFragment, this)
    }

    override fun onBackPressed() {
        if (drawer_layout.isDrawerOpen(GravityCompat.START)) {
            drawer_layout.closeDrawer(GravityCompat.START)
        } else {
            super.onBackPressed()
        }
    }

    override fun onCreateOptionsMenu(menu: Menu): Boolean {
        // Inflate the menu; this adds items to the action bar if it is present.
        menuInflater.inflate(R.menu.home, menu)
        return true
    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        when (item.itemId) {
            R.id.action_settings -> return true
            else -> return super.onOptionsItemSelected(item)
        }
    }

}

LocationController.kt

package com.edijae.crusar.reporter.controllers

import android.annotation.SuppressLint
import android.os.Bundle
import android.support.v7.app.AppCompatActivity
import com.google.android.gms.common.ConnectionResult
import com.google.android.gms.common.api.GoogleApiClient
import com.google.android.gms.location.LocationServices
import com.google.android.gms.location.places.Places
import com.google.android.gms.maps.GoogleMap
import com.google.android.gms.maps.OnMapReadyCallback
import com.google.android.gms.maps.SupportMapFragment

class LocationController :
        GoogleApiClient.OnConnectionFailedListener,
        GoogleApiClient.ConnectionCallbacks,
        OnMapReadyCallback {

    var map: GoogleMap? = null
    lateinit var apiClient: GoogleApiClient

    constructor(mapFragment: SupportMapFragment, activity: AppCompatActivity) {
        apiClient = GoogleApiClient.Builder(activity)
                .enableAutoManage(activity, this)
                .addConnectionCallbacks(this)
                .addApi(LocationServices.API)
                .addApi(Places.GEO_DATA_API)
                .addApi(Places.PLACE_DETECTION_API)
                .build()
        apiClient.connect()
        mapFragment.getMapAsync(this)
    }

    override fun onMapReady(p0: GoogleMap?) {
        map = p0
        val uiSettings = map?.getUiSettings()
        uiSettings?.isMyLocationButtonEnabled = true
        uiSettings?.isCompassEnabled = true
        uiSettings?.isMapToolbarEnabled = false
        uiSettings?.isTiltGesturesEnabled = true
        uiSettings?.isZoomControlsEnabled = true

        map?.setMapType(GoogleMap.MAP_TYPE_NORMAL)
        map?.setTrafficEnabled(true)
        map?.setBuildingsEnabled(true)
        map?.setIndoorEnabled(true)
        map?.setMyLocationEnabled(true)
    }

    override fun onConnected(p0: Bundle?) {
    }

    override fun onConnectionSuspended(p0: Int) {
    }

    override fun onConnectionFailed(p0: ConnectionResult) {
    }
}