title: GoogleMap class object throw Nullpointer Exception
body: <p>friends, I am getting NullPointer error ,on <strong>addMarker()</strong></p>
  
  <p>Below is my sample code.</p>
  
  <pre><code>GoogleMap myMap;
  android.support.v4.app.FragmentManager myFragmentManager = getSupportFragmentManager();
  SupportMapFragment myMapFragment = (SupportMapFragment)myFragmentManager.findFragmentById(R.id.map);
  myMap = myMapFragment.getMap();
  myMap.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker"));
  myMap.setMyLocationEnabled(true);
  myMap.getUiSettings().setZoomControlsEnabled(true);
  myMap.getUiSettings().setCompassEnabled(true);
  myMap.getUiSettings().setMyLocationButtonEnabled(true);
  </code></pre>
  
  <p>Error message like NullPointer at line </p>
  
  <pre><code>myMap.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker"));
  </code></pre>
  
  <p><strong>main.xml</strong></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout 
      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:orientation="vertical"
      tools:context=".DemoMapActiviy" &gt;
  
  &lt;TextView
      android:id="@+id/textView"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Large Text"
      android:textAppearance="?android:attr/textAppearanceLarge" /&gt;
  
  &lt;fragment
      android:id="@+id/map"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      class="com.google.android.gms.maps.SupportMapFragment"/&gt;
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>any idea how can i solve it?</p>