Test.java

//ini taru di main_activity.xml

<fragment
            android:id="@+id/map"
            android:name="com.google.android.gms.maps.SupportMapFragment"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_marginBottom="68dp"
            tools:context="id.my.asmith.ktg001.ContentActivity.DetailActivity" />
            
            
baru di MainActivity.java
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(map);
        mapFragment.getMapAsync(this);

jang lupa 
implements OnMapReadyCallback