Modify Maps Fragments in ActionBar Tab

Question

I've read a lot of different threads but none of the answers seem to work or fit my code.

I am trying to create an app with three tabs, one of which is a maps fragment. At the moment it runs fine and I can swipe between the tabs and the map does load and is usable, but whenever I try to add markers or enable location the app crashes on load. So I'm sure I am missing something obvious.

Code:

MainActivity.java

    public class MainActivity extends ActionBarActivity implements ActionBar.TabListener {

    SectionsPagerAdapter mSectionsPagerAdapter;

    ViewPager mViewPager;

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

        final ActionBar actionBar = getSupportActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

        mViewPager = (ViewPager) findViewById(R.id.pager);
        mViewPager.setAdapter(mSectionsPagerAdapter);

        mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
            @Override
            public void onPageSelected(int position) {
                actionBar.setSelectedNavigationItem(position);
            }
        });

        for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
            actionBar.addTab(actionBar.newTab()
                    .setText(mSectionsPagerAdapter.getPageTitle(i))
                    .setTabListener(this));
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
        mViewPager.setCurrentItem(tab.getPosition());
    }

    @Override
    public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
    }

    @Override
    public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
    }

    public class SectionsPagerAdapter extends FragmentPagerAdapter {

        public SectionsPagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            switch (position) {
                case 0:
                    return StatsFragment.newInstance(0);
                case 1:
                    return MapsFragment.newInstance(1);
                case 2:
                    return GraphsFragment.newInstance(2);
            }
            return null;
        }

        @Override
        public int getCount() {
            // Show 3 total pages.
            return 3;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            Locale l = Locale.getDefault();
            switch (position) {
                case 0:
                    return getString(R.string.title_section1).toUpperCase(l);
                case 1:
                    return getString(R.string.title_section3).toUpperCase(l);
                case 2:
                    return getString(R.string.title_section2).toUpperCase(l);
            }
            return null;
        }
    }
}

activity_main.xml

<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:id="@+id/pager"
android:layout_width="match_parent" android:layout_height="match_parent"
tools:context=".MainActivity" />

MapsFragment.java

    public class MapsFragment extends Fragment {

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        super.onCreateView(inflater, container, savedInstanceState);
        View view = inflater.inflate(R.layout.fragment_map, container, false);
        return view;
    }

    public MapsFragment() {
    }

    public static final String ARG_SECTION_NUMBER = "section_number";

    public static MapsFragment newInstance(int sectionNumber) {
        MapsFragment fragment = new MapsFragment();
        Bundle args = new Bundle();
        args.putInt(ARG_SECTION_NUMBER, sectionNumber);
        fragment.setArguments(args);
        return fragment;
    }
}

fragment_map.xml

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ffffd073">

    <fragment
        android:name="com.google.android.gms.maps.MapFragment"
        android:id="@+id/map_fragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

Any help or advice would be fantastic, I'm sure I've just done something wrong and/or missing something.

Edit: Logcat:

01-22 23:35:17.598  18294-18294/com.example.mark.skipalalpha E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.mark.skipalalpha, PID: 18294
java.lang.NullPointerException: Attempt to invoke virtual method 'void com.google.android.gms.maps.GoogleMap.setMyLocationEnabled(boolean)' on a null object reference
        at com.example.mark.skipalalpha.MapsFragment.onCreateView(MapsFragment.java:31)
        at android.support.v4.app.Fragment.performCreateView(Fragment.java:1786)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:947)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1126)
        at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:739)
        at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1489)
        at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:486)
        at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:1073)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:919)
        at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1441)
        at android.view.View.measure(View.java:17462)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5472)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
        at android.view.View.measure(View.java:17462)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5472)
        at android.support.v7.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:453)
        at android.view.View.measure(View.java:17462)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5472)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
        at android.view.View.measure(View.java:17462)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5472)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
        at android.view.View.measure(View.java:17462)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5472)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
        at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2601)
        at android.view.View.measure(View.java:17462)
        at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2075)
        at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1208)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1417)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1096)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5981)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:795)
        at android.view.Choreographer.doCallbacks(Choreographer.java:599)
        at android.view.Choreographer.doFrame(Choreographer.java:560)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:781)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5466)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:938)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:733)

2nd Edit:

If I add the two googleMap lines then the app crashes.

    public class MapsFragment extends Fragment {

    GoogleMap googleMap;

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        super.onCreateView(inflater, container, savedInstanceState);
        View view = inflater.inflate(R.layout.fragment_map, container, false);

        // Added two googleMap entries below causes the crash
        googleMap.setMyLocationEnabled(true);
        googleMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);

        return view;
    }

    public MapsFragment() {
    }

    public static final String ARG_SECTION_NUMBER = "section_number";

    public static MapsFragment newInstance(int sectionNumber) {
        MapsFragment fragment = new MapsFragment();
        Bundle args = new Bundle();
        args.putInt(ARG_SECTION_NUMBER, sectionNumber);
        fragment.setArguments(args);
        return fragment;
    }
}

Answer 1

I tried about one hour, and it works, Use the MapView to first set up the Map. here the solution:

MapsFragment.java

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapView;
import com.google.android.gms.maps.MapsInitializer;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.CameraPosition;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;


public class MapsFragment extends Fragment {


    MapView mMapView;
    private GoogleMap googleMap;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // inflat and return the layout
        View v = inflater.inflate(R.layout.fragment_map, container,
                false);
        mMapView = (MapView) v.findViewById(R.id.mapView);
        mMapView.onCreate(savedInstanceState);

        // Need to get the map to display at once
        mMapView.onResume();

        try {
            MapsInitializer.initialize(getActivity().getApplicationContext());
        } catch (Exception e) {
            e.printStackTrace();
        }

        googleMap = mMapView.getMap();
        // latitude and longitude
        double latitude = 17.385044;
        double longitude = 78.486671;

        // create marker
        MarkerOptions marker = new MarkerOptions().position(
                new LatLng(latitude, longitude)).title("Hello Maps");

        // Changing marker icon
        marker.icon(BitmapDescriptorFactory
                .defaultMarker(BitmapDescriptorFactory.HUE_ROSE));

        // adding marker
        googleMap.addMarker(marker);
        CameraPosition cameraPosition = new CameraPosition.Builder()
                .target(new LatLng(17.385044, 78.486671)).zoom(12).build();
        googleMap.animateCamera(CameraUpdateFactory
                .newCameraPosition(cameraPosition));

        return v;
    }

    @Override
    public void onResume() {
        super.onResume();
        mMapView.onResume();
    }

    @Override
    public void onPause() {
        super.onPause();
        mMapView.onPause();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        mMapView.onDestroy();
    }

    @Override
    public void onLowMemory() {
        super.onLowMemory();
        mMapView.onLowMemory();
    }

    public MapsFragment() {
    }

    public static final String ARG_SECTION_NUMBER = "section_number";

    public static MapsFragment newInstance(int sectionNumber) {
        MapsFragment fragment = new MapsFragment();
        Bundle args = new Bundle();
        args.putInt(ARG_SECTION_NUMBER, sectionNumber);
        fragment.setArguments(args);
        return fragment;
    }
}

Then, change your fragment_map.xml to this:

<?xml version="1.0" encoding="utf-8"?>
<com.google.android.gms.maps.MapView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/mapView"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

You can change lots of function in MapsFragment, such as Markers.