Google Maps标签内的片段

Question

I have a main activity that has 2 tabs that are created in it (im using the android studio viewpager tabs example as a base). I also have a sample maps activity that I would like to put inside of the 2nd tab. I am not too sure how to do this, and was looking for some guidance.

So here is the SectionsPagerAdapter that is inside of the main activity, and I believe this is where I am supposed to do so, but do I call an intent to launch the activity that creates the map fragment, or is there a way to do this directly?

    public class SectionsPagerAdapter extends FragmentPagerAdapter {

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

    @Override
    public Fragment getItem(int position) {
        //so here?
        return PlaceholderFragment.newInstance(position + 1);
    }

    @Override
    public int getCount() {
        return 2;
    }

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

and here is the MapView.java:

public class MapView extends ActionBarActivity {

    private GoogleMap map;

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

    @Override
    protected void onResume() {
        super.onResume();
        setUpMapIfNeeded();
    }

    private void setUpMapIfNeeded() {
        if (map == null) {
            map = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
                    .getMap();
            if (map != null) {
                setUpMap();
            }
        }
    }

    private void setUpMap() {
        //map.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker"));
    }
}

and lastly here is the xml for the fragment for the map

<fragment xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/map"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MapsView" />

I think this is all you will need, but I can add other parts if need be. Thanks

Answer 1

The ViewPager only handles Fragments as its child, so you need to change your MapView into a Fragment so that the ViewPager can host it. Instead of OnCreate, you will have :

@Override
 public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.fragment_map_view, container, false);
    return v;
}

Then in the adapter, you should change the getItem method to :

@Override
public Fragment getItem(int position) {
    switch (position) {
        case 0:
            return PlaceHolderFragment.newInstance();
        case 1:
            return MapViewFragment.newInstance();
    }
}

In your case, you should use one fragment per child of your ViewPager. On the default page, you will see the PlaceHolderFragment, and when swipping to the next page, you will see the MapViewFragment.

The last thing to do is updating your xml file. You should use the code you provided only if you want the Activity to handle the Fragment. But in this case, the Fragment is hosted by the ViewPager, so it should have it's own layout. You should have something like that :

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/map"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MapsView" />

Hope it helped !