how to open a new fragment using RecyclerView - android-fragments

Question

I am trying to make an app that which is like a place picker, meaning you write down a product like pizza or burger, and u get all the places around you that have pizza or burger.
now I'm using RecyclerView in my fragment and i also have Map fragment
when you click on an item in the RV, it will show its location on the map using the map fragment.
my problem is when I'm clicking on an item in the recyclerview i get nullpointerexception
here is my code of the first fragment
public class PlacesFragment extends Fragment implements LoaderManager.LoaderCallbacks<Cursor> , AdapterView.OnItemClickListener{
ClickListener listener;
static Places places;
PlacesAdapter adapter;
public FragmentManager fm;
MyMapFragment mapFragment;
Cursor cursor;
public PlacesFragment() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View myFragView= inflater.inflate(R.layout.fragment_places, container, false);
RecyclerView rv= (RecyclerView)myFragView.findViewById(R.id.placesRecyclerView);
//this create the line beetween every list to do so i have import to the build gradle a flexible divider
rv.addItemDecoration(new HorizontalDividerItemDecoration.Builder(getActivity()).color(Color.BLACK).build());
cursor = getActivity().getContentResolver().query(CONTENT_URI, null, null, null, null);
adapter= new PlacesAdapter(cursor, getActivity());
rv.setAdapter(adapter);
adapter.notifyItemRangeChanged(cursor.getPosition(), cursor.getCount());
adapter.notifyDataSetChanged();
rv.setLayoutManager(new LinearLayoutManager(getActivity()));
rv.addOnItemTouchListener(new RecyclerTouchListener(getActivity(), rv, new ClickListener() {
#Override
public void onPlaceClick(String latlng) {
//when i click on a place it will go to the map fragment
// Toast.makeText(getActivity(), "on click" + position, Toast.LENGTH_LONG).show();
/* FragmentManager fm = getFragmentManager();
// get the map object from the fragment:
mapFragment = MyMapFragment.newInstance(places);
FragmentTransaction ft = fm.beginTransaction();
ft.replace(R.id.fragmantContainer, mapFragment, "map");
ft.addToBackStack(null);
ft.commit();*/
}
})
);
// getLoaderManager().initLoader(1, null,);
return myFragView;
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
try {
listener = (ClickListener)context;
} catch (ClassCastException e) {
throw new ClassCastException("context " + context.toString()
+ "must implement PlacesFragmantListener!");
}
}
#Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
// CursorLoader c=getContext().getContentResolver().query(PlacesContract.Places.CONTENT_URI, null, null,null, null);
return new CursorLoader(getActivity(),CONTENT_URI, null, null,null, null );
}
#Override
public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
}
#Override
public void onLoaderReset(Loader<Cursor> loader) {
}
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
}
public static interface PlacesFragmantListener {
public void onLocationSelected(Places places);
}
class RecyclerTouchListener implements RecyclerView.OnItemTouchListener{
private GestureDetector gestureDetector;
private ClickListener clickListener;
MyMapFragment mapFragment;
public RecyclerTouchListener(Context context, RecyclerView recyclerView, ClickListener clickListener){
gestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener(){
#Override
public boolean onSingleTapUp(MotionEvent e) {
return true;
}
#Override
public void onLongPress(MotionEvent e) {
super.onLongPress(e);
}
});
this.clickListener = clickListener;
}
#Override
public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {
View child = rv.findChildViewUnder(e.getX(),e.getY());
return false;
}
#Override
public void onTouchEvent(RecyclerView rv, MotionEvent e) {
Log.d("PlaceAdapter", "onTouchEvent"+e);
}
#Override
public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) {
}
}
}
here is my map fragment
public class MyMapFragment extends Fragment {
public MyMapFragment(){
}
public static MyMapFragment newInstance(Places places) {}
if (places == null) {
places = new Places(0,"no Location selected","","", "");
}
// the arguments to pass
Bundle args = new Bundle();
args.putString("location", places.getLocation());
args.putDouble("lat", location.getLat());
args.putDouble("lon", location.getLon());
MyMapFragment mapFragmant = new MyMapFragment();
mapFragmant.setArguments(args);
return mapFragmant;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.mapfragment, container, false);
Bundle b=getArguments();
String latlng= b.getString("location");
Log.d("fragment...", latlng);
String[] latlongarr= latlng.split(",");
double lat= Double.parseDouble(latlongarr[0]);
double lon= Double.parseDouble(latlongarr[1]);
FragmentManager fm = getFragmentManager();
MapFragment mapFragment = (MapFragment) fm.findFragmentById(R.id.map);
// get the map object from the fragment:
GoogleMap map = mapFragment.getMap();
if(map!= null) {
// setup the map type:
map.setMapType(GoogleMap.MAP_TYPE_HYBRID);
// setup map position and zoom
LatLng position = new LatLng(b.getDouble("lat"), b.getDouble("lon"));
CameraUpdate update = CameraUpdateFactory.newLatLngZoom(position, 15);
map.moveCamera(update);
}
return view;
}
}
here is my adapter
public class PlacesAdapter extends RecyclerView.Adapter<PlacesAdapter.PlaceHolder> {
private Cursor cursor;
private Context context;
private static TextView placeName, address, distance, url;
public static ImageView imgplace;
public static PlaceHolder.ClickListener clickListener;
private static Places place;
private DataSetObserver mDataSetObserver;
MyMapFragment mapFragment;
private boolean mDataValid;
ClickListener listener;
public PlacesAdapter(Cursor cursor, Context context) {
this.context = context;
this.cursor = cursor;
mDataSetObserver = new NotifyingDataSetObserver();
if (cursor != null) {
cursor.registerDataSetObserver(mDataSetObserver);
}
}
#Override
public PlaceHolder onCreateViewHolder(ViewGroup parent, int viewType) {
// cursor.setNotificationUri(context.getContentResolver(), CONTENT_URI);
LayoutInflater inflater = LayoutInflater.from(context);
View myView = inflater.inflate(R.layout.single_place, parent, false);
PlaceHolder placeHolder = new PlaceHolder(myView, new PlaceHolder.PlacesFragmantListener() {
#Override
public void onLocationSelected(Places places) {
}
});
return placeHolder;
}
#Override
public void setHasStableIds(boolean hasStableIds) {
super.setHasStableIds(true);
}
#Override
public void onBindViewHolder(PlacesAdapter.PlaceHolder holder, final int position) {
if (cursor.moveToPosition(position)) {
int column_number = cursor.getColumnIndex(PLACES_NAME);
String name = cursor.getString(column_number);
placeName.setText(name);
int column_number2 = cursor.getColumnIndex(PLACES_ADDRESS);
String adr = cursor.getString(column_number2);
address.setText(adr);
int column_number3 = cursor.getColumnIndex(PLACES_DISTANEC);
String dis = cursor.getString(column_number3);
distance.setText(dis);
int column_number4 = cursor.getColumnIndex(PLACE_PHOTO);
String photo = cursor.getString(column_number4);
if(!photo.equals(""))
{
GoogleAccess.myImageDownloader loader= new GoogleAccess.myImageDownloader(imgplace);
loader.execute(photo);
}
}
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(context, "Item click at " + position, Toast.LENGTH_LONG).show();
if(cursor.moveToPosition(position))
{
String latlong= cursor.getString(cursor.getColumnIndex(PlacesDbconstanst.CurrentPlaces.PLACES_DISTANEC));
listener.onPlaceClick(latlong);
}
}
});
}
public void setClickListener(PlaceHolder.ClickListener clickListener){
this.clickListener = clickListener;
}
#Override
public int getItemCount() {
return cursor.getCount();
}
public static class PlaceHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
PlacesFragmantListener listener;
public PlaceHolder(View itemView, PlacesFragmantListener placesFragmantListener) {
super(itemView);
listener = placesFragmantListener;
placeName = (TextView) itemView.findViewById(R.id.placeNametextView);
address = (TextView) itemView.findViewById(R.id.addressTextView);
distance = (TextView) itemView.findViewById(R.id.distanceTextView);
imgplace = (ImageView) itemView.findViewById(R.id.placesImageViewId);
imgplace.setOnClickListener(this);
itemView.setOnClickListener(this);
}
RecyclerView rv;
#Override
public void onClick(View v) {
if(clickListener!=null){
clickListener.itemClicked(v, getPosition());
}
}
public static interface PlacesFragmantListener {
void onLocationSelected(Places places);
}
public interface ClickListener{
public void itemClicked (View view, int position);
}
}
private class NotifyingDataSetObserver extends DataSetObserver {
#Override
public void onChanged() {
super.onChanged();
mDataValid = true;
notifyDataSetChanged();
}
#Override
public void onInvalidated() {
super.onInvalidated();
mDataValid = false;
notifyDataSetChanged();
}
}
}
can you tell me what i did wrong
here is the log comment
03-30 04:55:28.042 2318-2318/com.myapps.pinkas.placesofintrest W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0xa4c8cb20)
03-30 04:55:28.042 2318-2318/com.myapps.pinkas.placesofintrest E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.myapps.pinkas.placesofintrest, PID: 2318
java.lang.NullPointerException
at com.myapps.pinkas.placesofintrest.PlacesAdapter$2.onClick(PlacesAdapter.java:112)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)

Answer 1

distance = (TextView) itemView.findViewById(R.id.distanceTextView);
is this line come in 112 in your class file, it's seems like, you have not defined view id or view in XML, please check line number 112 in PlacesAdapter.class

Answer 2

Problem 1: Setting onclick listener twice. In onbindviewholder you have put holder.itemView.setOnclicklistener and then again in static class viewholder, you have put itemview.setOnclickListener. When you assign setOnclicklistener inside the static viewholder class, it means it will behave in a particular way uninfluenced by values present in any other views (like textview, imageview) or any such factors which depend on some 'value' property of the views. For most purposes you should have setOnClicklistener onto the itemview/textview/etc inside the static viewholder class which in your case is called placeholder.
Problem 2: Here is the reason why I believe you are getting NullPointerException. onbindviewholder has access to only the views declared in static viewholder class. If you want itemview to be accessible to onbindviewholder then make the following changes:
public static class PlaceHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
PlacesFragmantListener listener;
View iv;
public PlaceHolder(View itemView, PlacesFragmantListener placesFragmantListener) {
super(itemView);
iv = (View)itemView;
//then rest of the code
Now in your onbindviewholder write the following instead of holder.itemview.setonclicklistener
holder.iv.setonclicklistener...
Problem 3: in your static viewholder, you have put:
imgplace.setOnClickListener(this);
itemView.setOnClickListener(this);
itemview is the layout in which imgplace exists. And you have setonclicklistener on both of them. This is like putting a button on a button. It makes no sense. I think this will lead you into lot of mess. For some reason you want both to perform the same function on being clicked (you have put 'this' inside setOnClickListener). This is completely illogical. So set the clicklistener to either imgplace or itemview but not both