title: cannot implement OnMapReadyCallback
body: <p>I'm working on a project with Navigation Drawer, and one of the fragments should be with Google Map.</p>
  
  <p>I'm trying to implement a OnMapReadyCallback interface but it doesn't resolve that symbol.</p>
  
  <p>I have already tried to update Google Play services.
  Here's my build.gradle :app</p>
  
  <pre><code>   apply plugin: 'com.android.application'
  
  android {
      compileSdkVersion 23
      buildToolsVersion "23.0.2"
  
      defaultConfig {
          applicationId "com.zakrzewskibartlomiej.cv_v3"
          minSdkVersion 19
          targetSdkVersion 23
          versionCode 1
          versionName "1.0"
          multiDexEnabled true
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      compile fileTree(dir: 'libs', include: ['*.jar'])
      testCompile 'junit:junit:4.12'
      compile 'com.android.support:appcompat-v7:23.4.0'
      compile 'de.hdodenhof:circleimageview:2.0.0'
      compile 'com.android.support:design:23.4.0'
      compile 'com.android.support:recyclerview-v7:23.4.0'
      compile 'com.google.android.gms:play-services:9.0.1'
      compile 'com.google.android.gms:play-services-maps:8.4.0'
  
  
  }
  </code></pre>
  
  <p>And here I'm trying to implement this</p>
  
  <pre><code>import com.google.android.gms.maps.OnMapReadyCallback;
  import com.google.android.gms.maps.SupportMapFragment;
  
  public class MainActivity extends AppCompatActivity
          implements NavigationView.OnNavigationItemSelectedListener, onMapReadyCallback {
  
      NavigationView navigationView = null;
      Toolbar toolbar = null;
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
          toolbar = (Toolbar) findViewById(R.id.toolbar);
          setSupportActionBar(toolbar);
  
          //set the fragment initially
          MainFragment fragment = new MainFragment();
          android.support.v4.app.FragmentTransaction fragmentTransaction =
                  getSupportFragmentManager().beginTransaction();
          fragmentTransaction.replace(R.id.fragment_container, fragment);
          fragmentTransaction.commit();
  
          FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
          fab.setOnClickListener(new View.OnClickListener() {
              @Override
              public void onClick(View view) {
                  Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                          .setAction("Action", null).show();
              }
          });
  
          DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
          ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                  this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
          drawer.setDrawerListener(toggle);
          toggle.syncState();
  
          navigationView = (NavigationView) findViewById(R.id.nav_view);
          navigationView.setNavigationItemSelectedListener(this);
      }
  </code></pre>
  
  <p>How can I fix this? </p>