Develop Reference

Passing events from DialogFragment back to RecyclerView Adapter

My fragment has a Recycler View. Therefore I have a RecyclerView Adapter too. From this Adapter, I am opening an AlertDialog. When I click OK, I need to pass the onclick event from my DialogFragment back to my RecyclerView Adapter.
Currently, I am doing it like here, but this passes the event back to the activity and not to the RecyclerView Adapter.
public class FreshwaterRecyclerViewAdapter extends RecyclerView.Adapter<FreshwaterRecyclerViewAdapter.ViewHolder> implements BiotopeDialogFragment.NoticeDialogListener {
private List<Biotope> data;
private LayoutInflater layoutInflater;
FreshwaterRecyclerViewAdapter(Context context, List<Biotope> data) {
this.layoutInflater = LayoutInflater.from(context);
this.data = data;
}
//The dialog fragment receives a reference to this Activity through the
//Fragment.onAttach() callback, which it uses to call the following methods
//defined by the NoticeDialogFragment.NoticeDialogListener interface
#Override
public void onDialogPositiveClick(DialogFragment dialog) {
notifyItemInserted(getItemCount()-1);
}
#Override
public void onDialogNegativeClick(DialogFragment dialog) {
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView;
if (viewType == R.layout.biotope_cardview){
itemView = layoutInflater.inflate(R.layout.biotope_cardview, parent, false);
} else {
itemView = layoutInflater.inflate(R.layout.biotope_add_button, parent, false);
}
return new ViewHolder(itemView);
}
#Override
public void onBindViewHolder(#NonNull ViewHolder holder, int position) {
if (position == data.size()) {
holder.imageButtonAddBiotope.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
FragmentManager fragmentManager = ((AppCompatActivity) layoutInflater.getContext()).getSupportFragmentManager();
DialogFragment dialog = new BiotopeDialogFragment();
dialog.show(fragmentManager, "NoticeDialogFragment");
}
});
} else {
holder.textViewBiotopeTitle.setText(getItem(position).name);
Picasso.get().load(Uri.parse(getItem(position).imageUri)).into(holder.imageViewBiotope);
LastValuesRecyclerViewAdapter recyclerAdapter = new LastValuesRecyclerViewAdapter(layoutInflater.getContext(), getData());
holder.recyclerViewLastValues.setLayoutManager(new LinearLayoutManager(layoutInflater.getContext(), LinearLayoutManager.HORIZONTAL, false));
holder.recyclerViewLastValues.setAdapter(recyclerAdapter);
}
}
//total number of rows
#Override
public int getItemCount() {
return data.size() + 1; //+1 for the add button
}
#Override
public int getItemViewType(int position) {
return (position == data.size()) ? R.layout.biotope_add_button : R.layout.biotope_cardview;
}
public static class ViewHolder extends RecyclerView.ViewHolder {
private TextView textViewBiotopeTitle;
private ImageView imageViewBiotope;
private RecyclerView recyclerViewLastValues;
private ImageButton imageButtonAddBiotope;
public ViewHolder(View view) {
super(view);
textViewBiotopeTitle = (TextView) view.findViewById(R.id.textViewBiotopeTitle);
imageViewBiotope = (ImageView) view.findViewById(R.id.imageViewBiotopeCardview);
recyclerViewLastValues = (RecyclerView) view.findViewById(R.id.recyclerViewLastValues);
imageButtonAddBiotope = (ImageButton) view.findViewById(R.id.imageButtonAddBiotope);
}
}
Biotope getItem(int id) {
return data.get(id);
}
private List<String> getData() {
List<String> data = new ArrayList<>();
data.add("PO4");
data.add("NO3");
return data;
}
}
This is my dialog.
public class BiotopeDialogFragment extends DialogFragment {
private NoticeDialogListener listener;
public interface NoticeDialogListener {
public void onDialogPositiveClick(DialogFragment dialog);
public void onDialogNegativeClick(DialogFragment dialog);
}
//Override the Fragment.onAttach() method to instantiate the NoticeDialogListener
#Override
public void onAttach(#NonNull Context context) {
super.onAttach(context);
//Verify that the host activity implements the callback interface
try {
//Instantiate the NoticeDialogListener so we can send events to the host
listener = (NoticeDialogListener) context;
} catch (ClassCastException e) {
//The activity doesn't implement the interface, throw exception
throw new ClassCastException("FreshwaterRecyclerViewAdapter must implement NoticeDialogListener | Context: " + context.toString());
}
}
public static final String TAG = "biotope_dialog_fragment";
private ActivityResultLauncher<Intent> activityResultLauncher;
private Uri imageUri = null;
#NonNull
#Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
MaterialAlertDialogBuilder builder = new MaterialAlertDialogBuilder(getContext());
LayoutInflater inflater = requireActivity().getLayoutInflater();
//Inflate and set the layout for the dialog
//Pass null as the parent view because its going in the dialog layout
View view = inflater.inflate(R.layout.fragment_dialog_biotope, null, false);
builder.setView(view);
View colorPickerPreviewView = view.findViewById(R.id.colorPickerPreviewView);
ColorPickerView colorPickerView = view.findViewById(R.id.colorPickerView);
ImageView imageViewBiotope = view.findViewById(R.id.imageViewBiotopePreview);
TextInputEditText textFieldBiotopeName = view.findViewById(R.id.textFieldBiotopeName);
builder.setTitle("New biotope")
.setPositiveButton("ok", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int id) {
BiotopeDatabase database = BiotopeDatabase.getDbInstance(requireContext().getApplicationContext());
Biotope biotope = new Biotope();
if (textFieldBiotopeName.getText() != null) {
biotope.name = textFieldBiotopeName.getText().toString();
} else {
biotope.name = "";
}
if (imageUri != null) {
biotope.imageUri = imageUri.toString();
} else {
biotope.imageUri = "";
}
biotope.color = colorPickerView.getColor();
database.biotopeDao().insertAll(biotope);
//Send the positive button event back to the host activity
listener.onDialogPositiveClick(BiotopeDialogFragment.this);
}
})
.setNegativeButton("noke", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
//Send the negative button event back to the host activity
listener.onDialogNegativeClick(BiotopeDialogFragment.this);
Objects.requireNonNull(BiotopeDialogFragment.this.getDialog()).cancel();
}
});
return builder.create();
}
public static BiotopeDialogFragment display(FragmentManager fragmentManager) {
BiotopeDialogFragment fragment = new BiotopeDialogFragment();
fragment.show(fragmentManager, TAG);
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public void onViewCreated(#NonNull View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
}
}
This is my fragment building the RecyclerView. Alternatively, I can pass the event back to the fragment if it is not possible to pass it to the adapter.
public class BiotopesFragment extends Fragment {
private FreshwaterRecyclerViewAdapter recyclerAdapter;
public static BiotopesFragment newInstance(String param1, String param2) {
BiotopesFragment fragment = new BiotopesFragment();
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View root = inflater.inflate(R.layout.fragment_biotopes, container, false);
RecyclerView recyclerViewFreshwater = (RecyclerView) root.findViewById(R.id.recyclerViewFreshwater);
recyclerAdapter = new FreshwaterRecyclerViewAdapter(getContext(), getData());
recyclerViewFreshwater.setLayoutManager(new LinearLayoutManager(getContext(), LinearLayoutManager.HORIZONTAL, false));
recyclerViewFreshwater.setAdapter(recyclerAdapter);
DividerItemDecoration dividerItemDecoration = new DividerItemDecoration(getContext(), DividerItemDecoration.VERTICAL);
recyclerViewFreshwater.addItemDecoration(dividerItemDecoration);
ItemTouchHelper itemTouchHelper = new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(ItemTouchHelper.START | ItemTouchHelper.END, 0) {
#Override
public boolean onMove(#NonNull RecyclerView recyclerView, #NonNull RecyclerView.ViewHolder viewHolder, #NonNull RecyclerView.ViewHolder target) {
int fromPosition = viewHolder.getAdapterPosition();
int toPosition = target.getAdapterPosition();
Collections.swap(getData(), fromPosition, toPosition);
recyclerView.getAdapter().notifyItemMoved(fromPosition, toPosition);
return false;
}
#Override
public void onSwiped(#NonNull RecyclerView.ViewHolder viewHolder, int direction) {
}
});
itemTouchHelper.attachToRecyclerView(recyclerViewFreshwater);
return root;
}
private List<Biotope> getData() {
BiotopeDatabase database = BiotopeDatabase.getDbInstance(requireContext().getApplicationContext());
BiotopeDao biotopeDao = database.biotopeDao();
return biotopeDao.getAll();
}
}

Ideal Way to do this to create all UI component in Fragment not in the adapter . Create an interface to handle events in the fragment and provide callback to the fragment from adapter. now your Fragment should create all the UI component .
Now coming to the
How to provide callback from dialog fragment to Fragment.
You can use setTargetFragment but its deprecated . Now you can use setFragmentResultListener instead of setTargetFragment(), its the safest way i think. Once you get the result back in fragment you can call any method of your adapter.

My app is getting crash without any errors if I use onClickListener in ParkActivity

I'm a beginner in Android Development and I have one doubt, How to pass from 2nd Activity into 3rd Activity
From MainActivity
TextView parkText = (TextView)findViewById(R.id.park);
parkText.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent i = new Intent(view.getContext(),ParkActivity.class);
startActivity(i);
}
});
From ParkActivity
public class ParkActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.place_list);
final ArrayList<Places> parkPlaceList = new ArrayList<Places>();
parkPlaceList.add(new Places("TowerPark",R.mipmap.chennai_hdpi));
parkPlaceList.add(new Places("TowerPark",R.mipmap.chennai_hdpi));
parkPlaceList.add(new Places("TowerPark",R.mipmap.chennai_hdpi));
parkPlaceList.add(new Places("TowerPark",R.mipmap.chennai_hdpi));
parkPlaceList.add(new Places("TowerPark",R.mipmap.chennai_hdpi));
parkPlaceList.add(new Places("TowerPark",R.mipmap.chennai_hdpi));
parkPlaceList.add(new Places("TowerPark",R.mipmap.chennai_hdpi));
PlaceAdapter itemsAdapter = new PlaceAdapter(this,parkPlaceList);
ListView placeList = (ListView)findViewById(R.id.list);
placeList.setAdapter(itemsAdapter);
}
}
From Places
package com.example.chennaitourapp;
public class Places {
private String mtextview;
private int mimageResourceId;
public Places(String textView, int imageResourceId){
mtextview = textView;
mimageResourceId = imageResourceId;
}
public String getMtextview() {
return mtextview;
}
public int getMimageResourceId() {
return mimageResourceId;
}
}
From PlaceAdapter
public class PlaceAdapter extends ArrayAdapter<Places> {
public PlaceAdapter(#NonNull Context context, ArrayList<Places>parkPlacelist) {
super(context, 0,parkPlacelist);
}
#NonNull
#Override
public View getView(int position, #Nullable View convertView, #NonNull ViewGroup parent) {
View listItemView = convertView;
if (listItemView == null){
listItemView = LayoutInflater.from(getContext()).inflate(R.layout.imagepname,parent,false);
}
Places placeListPosition = getItem(position);
TextView placesName = (TextView)listItemView.findViewById(R.id.text);
placesName.setText(placeListPosition.getMtextview());
ImageView placesImage = (ImageView)listItemView.findViewById(R.id.image);
placesImage.setImageResource(placeListPosition.getMimageResourceId());
return listItemView;
Now I have to pass from ParkActivity To ParkActivity2 and I created another Activity called ParkActivity2
If I touch or click textview from ParkActivity I need to go to ParkActivity and I know I have to use onClickListener which I already done in MainActivity but I need to know where I have to write that code
Actually I wrote that code in ParkActivity but my app is getting crashed without any errors.

In ParkActivity set onItemClickListener in your listView (which is placeList in your case) after setting the adapter.
placeList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
//go to ParkActivity2
startActivity(new Intent(context,ParkActivity2.class));
}
});
Don't forget to add your Activity in Manifest, if you added it manually.

Android: Sending a cardview from one fragment to another

I need some help for a summer project
This is my Events fragment
This is my MyList fragment
I'm using a RecyclerView+Cardview to display the Events. The idea is that the user can click the big plus on the right side of each card, and the card would be displayed in the MyList fragment. I would like to ask if it's possible to transfer a card directly from one fragment to another? Also, both fragments are contained within the same activity, which makes it a little trickier(I haven't found any available solutions).
If that is not possible, another way is to transfer the reference type object contained in the CardView to the MyList fragment. However, this is even less straightforward. This is because the button is inflated in the adapter, but there is no reference type object created here. I have seen many tutorials on using the Parcelable interface, however, I don't know how to implement it here when I'm unable to even create the object in the adapter. The reference object is created in another activity and stored in Firebase before it is read and displayed.
I'm going to attach my EventsAdapter.java and EventsItem.java and EventsFragment.java code below, but please let me know if I should include more code to describe the problem.
Thanks for reading my very long post!!
public class EventsAdapter extends RecyclerView.Adapter<EventsAdapter.EventsViewHolder> implements Filterable {
private ArrayList<EventsItem> mEventsList;
private ArrayList<EventsItem> mEventsListFull;
private EventsAdapter.OnItemClickListener mListener;
private Context mContext;
private DateFormat df = DateFormat.getDateInstance(DateFormat.MEDIUM, Locale.UK);
public interface OnItemClickListener {
void onItemClick(int position);
}
//the ViewHolder holds the content of the card
public static class EventsViewHolder extends RecyclerView.ViewHolder {
public ImageView mImageView;
public ImageView mAddButton;
public TextView mTextView1;
public TextView mTextView2;
public TextView mTextView3;
public TextView mTextView4;
public TextView mTextView5;
public EventsViewHolder(Context context, View itemView, final EventsAdapter.OnItemClickListener listener) {
super(itemView);
final Context context1 = context;
mImageView = itemView.findViewById(R.id.imageView);
mAddButton = itemView.findViewById(R.id.image_add);
mTextView1 = itemView.findViewById(R.id.title);
mTextView2 = itemView.findViewById(R.id.event_description);
mTextView3 = itemView.findViewById(R.id.date);
mTextView4 = itemView.findViewById(R.id.location);
mTextView5 = itemView.findViewById(R.id.time);
itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (listener != null) {
int position = getAdapterPosition();
if (position != RecyclerView.NO_POSITION) {
listener.onItemClick(position);
}
}
}
});
mAddButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String str1 = mTextView1.getText().toString();
String str2 = mTextView2.getText().toString();
String str3 = mTextView3.getText().toString();
String str4 = mTextView4.getText().toString();
String str5 = mTextView5.getText().toString();
Bundle bundle = new Bundle();
bundle.putString("title", str1);
bundle.putString("event description", str2);
bundle.putString("date", str3);
bundle.putString("location", str4);
bundle.putString("time", str5);
MylistFragment mlf = new MylistFragment();
mlf.setArguments(bundle);
}
});
}
}
//Constructor for EventsAdapter class. This ArrayList contains the
//complete list of items that we want to add to the View.
public EventsAdapter(Context context, ArrayList<EventsItem> EventsList) {
mEventsList = EventsList;
mContext = context;
mEventsListFull = new ArrayList<>(EventsList); // copy of EventsList for SearchView
}
//inflate the items in a EventsViewHolder
#NonNull
#Override
public EventsAdapter.EventsViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.event_item, parent, false);
EventsAdapter.EventsViewHolder evh = new EventsAdapter.EventsViewHolder(mContext, v, mListener);
return evh;
}
#Override
public void onBindViewHolder(#NonNull EventsAdapter.EventsViewHolder holder, int position) {
EventsItem currentItem = mEventsList.get(position);
holder.mImageView.setImageResource(currentItem.getProfilePicture());
holder.mTextView1.setText(currentItem.getTitle());
holder.mTextView2.setText(currentItem.getDescription());
holder.mTextView3.setText(df.format(currentItem.getDateInfo()));
holder.mTextView4.setText(currentItem.getLocationInfo());
holder.mTextView5.setText(currentItem.getTimeInfo());
}
#Override
public int getItemCount() {
return mEventsList.size();
}
public class EventsItem implements Occasion, Parcelable {
//fields removed for brevity
//constructor removed for brevity
}
public EventsItem() {
}
public EventsItem(Parcel in) {
profilePicture = in.readInt();
timeInfo = in.readString();
hourOfDay = in.readInt();
minute = in.readInt();
locationInfo = in.readString();
title = in.readString();
description = in.readString();
}
public static final Creator<EventsItem> CREATOR = new Creator<EventsItem>() {
#Override
public EventsItem createFromParcel(Parcel in) {
return new EventsItem(in);
}
#Override
public EventsItem[] newArray(int size) {
return new EventsItem[size];
}
};
//getter methods have been removed for brevity
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeInt(profilePicture);
dest.writeString(timeInfo);
dest.writeString(locationInfo);
dest.writeString(title);
dest.writeString(description);
dest.writeString(df.format(dateInfo));
dest.writeInt(hourOfDay);
dest.writeInt(minute);
}
}
public class EventsFragment extends Fragment {
ArrayList<EventsItem> EventsItemList;
FirebaseDatabase mDatabase;
DatabaseReference mDatabaseReference;
ValueEventListener mValueEventListener;
private RecyclerView mRecyclerView;
private RecyclerView.LayoutManager mLayoutManager;
private EventsAdapter mAdapter;
private View rootView;
public FloatingActionButton floatingActionButton;
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.fragment_events, container, false);
mDatabase = FirebaseDatabase.getInstance();
mDatabaseReference = mDatabase.getReference().child("Events");
createEventsList();
buildRecyclerView();
floatingActionButton = rootView.findViewById(R.id.fab);
floatingActionButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(getActivity(), EventsAdder.class);
startActivity(intent);
}
});
mValueEventListener = new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
EventsItemList.add(snapshot.getValue(EventsItem.class));
}
EventsAdapter eventsAdapter = new EventsAdapter(getActivity(), EventsItemList);
mRecyclerView.setAdapter(eventsAdapter);
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
};
mDatabaseReference.addValueEventListener(mValueEventListener);
setHasOptionsMenu(true);
Toolbar toolbar = rootView.findViewById(R.id.events_toolbar);
AppCompatActivity activity = (AppCompatActivity) getActivity();
activity.setSupportActionBar(toolbar);
return rootView;
}
public void createEventsList() {
EventsItemList = new ArrayList<>();
}
public void buildRecyclerView() {
mRecyclerView = rootView.findViewById(R.id.recyclerview);
mLayoutManager = new LinearLayoutManager(getContext());
mAdapter = new EventsAdapter(getActivity(), EventsItemList);
mRecyclerView.setLayoutManager(mLayoutManager);
mRecyclerView.setAdapter(mAdapter);
mRecyclerView.setItemAnimator(new DefaultItemAnimator());
}
}

If you would like to see the same CardView within the MyListFragment, you could have the MyListFragment contain a RecyclerView, and reuse the same EventsAdapter and EventsViewHolder. The only difference is that rather than populating the adapter with all the children of the "Events" from your database, you would only populate it with the single Event that you want.
Also, since you have made your Event class implement parcelable, you do not need to manually create the bundle when clicking the plus button.
I am assuming you have a single Activity, and you simply want to replace the EventsFragment with the MyListFragment. Checkout the docs for replacing one fragment with another.
Step 1:
Extend your onItemClickListener to look like:
public interface OnItemClickListener {
void onItemClick(int position);
void onPlusButtonClick(int position);
}
and adjust the code in your EventsViewHolder constructor to look like this when the plus button is clicked:
mAddButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (listener != null) {
// no need to manually create the bundle here
// you already have all the information you need
int position = getAdapterPosition();
if (position != RecyclerView.NO_POSITION) {
listener.onPlusButtonClick(position);
}
}
}
});
Step 2:
Implement our new method onPlusButtonClick. As per our discussion in the comments, it seems you do not implement this interface anywhere. You can implement it inside the constructor to your EventsAdapter:
public EventsAdapter(Context context, ArrayList<EventsItem> EventsList) {
mEventsList = EventsList;
mContext = context;
mEventsListFull = new ArrayList<>(EventsList); // copy of EventsList for SearchView
mListener = new OnItemClickListener() {
#Override
public void onItemClick() {
// handle clicking the entire view holder
// NOTE: inside your EventsViewHolder, it looks like you call this method on the entire itemView. This could 'swallow' the click on the plus button. You may need to adjust your code to handle this.
}
#Override
public void onPlusButtonClick(int position) {
MyListFragment myListFragment = new MyListFragment();
Event event = mEventsList.get(position);
Bundle bundle = new Bundle();
bundle.putExtra("event", event); // this will work due to implementing parcelable
myListFragment.setArguments(bundle);
// use mContext since im assuming we areinside adapter
// if in an Activity, no need to use context to get the fragment manager
FragmentTransaction transaction = mContext.getSupportFragmentManager().beginTransaction();
// Replace the EventsFragment with the MyListFragment
// and add the transaction to the back stack so the user can navigate back
transaction.replace(R.id.fragment_container, myListFragment);
transaction.addToBackStack(null);
// Commit the transaction
transaction.commit();
}
}
}
Step 3:
Inside your MyListFragments onCreateView() method:
#Override
public View onCreateView (
LayoutInflater inflater,
ViewGroup container,
Bundle savedInstanceState
) {
Bundle bundle = getArguments();
Event event = bundle.getExtra("event"); // again, will work due to implementing parcelable
// from here you should bind to a recycler view, and you can even reuse your adapter like so:
List<EventsItem> singleEventList = new List<EventsItem>();
singleEventList.add(event);
EventsAdapter adapter = new EventsAdapter(getActivity(), singleEventList);
// be sure to inflate and return your view here...
}
and you should be good to go!
I have left out bits of code here and there for simplicity.. but I hope this is understandable.
As a side note.. in your firebase database listener, it is bad practice to create a new EventsAdapter every single time your data is updated. Instead, you should update the data in the adapter with the new values. Do this by creating a public method inside the adapter such as replaceEvents(List<EventsItem> newEvents), and inside, replace mEventsList with the new events, then call notifyDataSetChanged().

Recyclerview doesn't show any data after swiping one of the rows

I've added swipe to my app, to delete specified note. For couple of days, I've facing problem with displaying data after swipe. For clarify:
Let's say, we have two items in recycler view. Whenever we swipe one of them, the second one should be visible, but it's not until I'll re-run the app. How I may solve it?
Main Activity
public class MainActivity extends AppCompatActivity implements MemoAdapter.OnNoteListener {
private static final String TAG = "MainActivity";
//Vars
private ArrayList<Note> mNotes = new ArrayList<>();
private MemoRepository mRepository;
private MemoAdapter mMemoAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mRepository = new MemoRepository(this);
Toolbar toolbar = (Toolbar) findViewById(R.id.memoToolbar);
setSupportActionBar(toolbar);
setTitle("My memos");
initRecyclerView();
}
//This method would be called after getting result from memo_content such as new memo, or edited existing memo.
#Override
protected void onResume() {
super.onResume();
getMemos();
}
private void getMemos(){
mRepository.getAllMemos().observe(this, new Observer<List<Note>>() {
#Override
public void onChanged(List<Note> notes) {
if (mNotes.size() > 0){
notes.clear();
}
if (notes != null){
mNotes.addAll(notes);
mMemoAdapter.watchMemoChanges((ArrayList<Note>) notes);
}
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.icon_menu, menu);
return super.onCreateOptionsMenu(menu);
}
#Override
public boolean onOptionsItemSelected(#NonNull MenuItem item) {
switch (item.getItemId()){
case R.id.addNewNote:
Toast.makeText(this, "Click!", Toast.LENGTH_SHORT).show();
startActivity(new Intent(this, memo_content.class));
break;
case R.id.deleteAllNotes:
Toast.makeText(this, "Delete!", Toast.LENGTH_SHORT).show();
mRepository.deleteAllMemos();
break;
}
return super.onOptionsItemSelected(item);
}
private void initRecyclerView(){
//UI
RecyclerView mRecyclerView = findViewById(R.id.recyclerView);
mRecyclerView.setHasFixedSize(true);
RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(this);
mMemoAdapter = new MemoAdapter(mNotes, this);
new ItemTouchHelper(itemTouch).attachToRecyclerView(mRecyclerView);
mRecyclerView.setLayoutManager(mLayoutManager);
mRecyclerView.setAdapter(mMemoAdapter);
}
#Override
public void onMemoClick(int position) {
Intent intent = new Intent(this, memo_content.class);
intent.putExtra("memo_content", mNotes.get(position));
startActivity(intent);
}
private ItemTouchHelper.SimpleCallback itemTouch = new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.START | ItemTouchHelper.LEFT) {
#Override
public boolean onMove(#NonNull RecyclerView recyclerView, #NonNull RecyclerView.ViewHolder viewHolder, #NonNull RecyclerView.ViewHolder target) {
return false;
}
#Override
public void onSwiped(#NonNull RecyclerView.ViewHolder viewHolder, int direction) {
mRepository.deleteMemo(mNotes.get(viewHolder.getAdapterPosition()));
Log.d(TAG, "onSwiped: "+mNotes.get(viewHolder.getAdapterPosition()));
}
};
}
Adapter
public class MemoAdapter extends RecyclerView.Adapter<MemoAdapter.MemoViewHolder> {
private ArrayList<Note> mNotes;
private OnNoteListener mListener;
public class MemoViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
TextView title, timestamp;
private MemoViewHolder(#NonNull final View itemView) {
super(itemView);
this.title = (TextView) itemView.findViewById(R.id.title);
this.timestamp = (TextView) itemView.findViewById(R.id.timestamp);
itemView.setOnClickListener(this);
}
#Override
public void onClick(View v) {
mListener.onMemoClick(getAdapterPosition());
}
}
public MemoAdapter(ArrayList<Note> notes, OnNoteListener listener) {
this.mNotes = notes;
this.mListener = listener;
}
#NonNull
#Override
public MemoViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.single_memo, parent, false);
return new MemoViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull MemoViewHolder holder, int position) {
holder.title.setText(mNotes.get(position).getTitle());
holder.timestamp.setText(mNotes.get(position).getTimestamp());
}
public void watchMemoChanges(ArrayList<Note> notes){
this.mNotes = notes;
notifyDataSetChanged();
}
#Override
public int getItemCount() {
return mNotes.size();
}
public interface OnNoteListener{
void onMemoClick(int position);
}

Short answer:
You need to remove the statement notes.clear() when you receive a change in the LiveData list from the database via the observer.
Detailed answer
When you first run your app, it will show all right list because the condition if (mNotes.size() > 0) is not met, and so the received list won't be cleared via notes.clear(), so the RecyclerView will display the right data.
But when you delete a note, then when the observer is triggered again with the new list, the condition if (mNotes.size() > 0) will be met, so you will clear the list that is coming from the database before feeding the adapter with it, so the RecyclerView will be free of data.
So to solve this please replace notes.clear(); with mNotes.clear();
So the right code will be:
private void getMemos(){
mRepository.getAllMemos().observe(this, new Observer<List<Note>>() {
#Override
public void onChanged(List<Note> notes) {
if (mNotes.size() > 0){
mNotes.clear();
}
if (notes != null){
mNotes.addAll(notes);
mMemoAdapter.watchMemoChanges((ArrayList<Note>) notes);
}
}
});
}
Wish that help you out.
I didn't examine the rest of code, please let me know if there is another issue to help more

Passing RecyclerView CardView Clicked Item Data To Activity

I have a question about passing clicked cardview data to activity, and here the full story :
I have an Activity called "Details", which contains 2 TextViews in it's layout, Title & Description .
I have setup a fragment ( tab_1 ) which contain the recyclerview codes and the the items data, each item of those contain : title & description .
What i want :
When the user click the item, it will open the Details Activity, and change Details layout title, with clicked item title, and the same for description .
I've manged to create the other activity as an example, and made intent to start it, plus adding "addOnTouchlistener" thanks to Stackoverflow, i've found the way to make it .
So, how to make this alive? I've tried many ways of the available answers on Stackoverflow, but all of them not working, or not related to my request .
Here are my files :
itemsdata.java :
public class itemsdata {
int CatPic;
String title;
String Descr;
int Exapnd;
int expand_no;
tab_1.java ( fragment )
public class tab_1 extends Fragment implements SearchView.OnQueryTextListener {
private RecyclerView mRecyclerView;
public RecyclingViewAdapter adapter;
private Activity context;
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View layout = inflater.inflate(R.layout.tab_1, container, false);
mRecyclerView = (RecyclerView)layout.findViewById(R.id.recycler_view);
mRecyclerView.addOnItemTouchListener(new RecyclerItemClickListener
(getContext(), new RecyclerItemClickListener.OnItemClickListener() {
#Override
public void onItemClick(View view, int position) {
Intent i = new Intent(view.getContext(), DetailsActivity.class);
view.getContext().startActivity(i);
}
}));
mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
adapter = new RecyclingViewAdapter(getActivity(),Listed());
mRecyclerView.setAdapter(adapter);
return layout;
}
#Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
inflater.inflate(R.menu.main, menu);
final MenuItem item = menu.findItem(R.id.action_search);
final SearchView searchView = (SearchView) MenuItemCompat.getActionView(item);
searchView.setOnQueryTextListener(this);
}
#Override
public boolean onQueryTextChange(String query) {
final List<itemsdata> filteredModelList = filter(Listed(), query);
adapter.animateTo(filteredModelList);
mRecyclerView.scrollToPosition(0);
return true;
}
#Override
public boolean onQueryTextSubmit(String query) {
return true;
}
private List<itemsdata> filter(List<itemsdata> models, String query) {
query = query.toLowerCase();
final List<itemsdata> filteredModelList = new ArrayList<>();
for (itemsdata model : models) {
final String text = model.title.toLowerCase();
if (text.contains(query)) {
filteredModelList.add(model);
}
}
return filteredModelList;
}
public List<itemsdata> Listed()
{
//Titles Strings
String sys_title1 = getString(R.string.system_item_title_1);
String sys_title2 = getString(R.string.system_item_title_2);
String sys_title3 = getString(R.string.system_item_title_3);
//Description Strings
String sys_descr1 = getString(R.string.system_item_desc_1);
String sys_descr2 = getString(R.string.system_item_desc_2);
String sys_descr3 = getString(R.string.system_item_desc_3);
//Adding New Cards
List<itemsdata> data = new ArrayList<>();
//Categories Icons New Items ** Make It The Same
int[] icons = {
R.drawable.facebook_icon ,
R.drawable.twitter_icon ,
R.drawable.twitter_icon
};
//Expand Button New Items
int[] expandbutton = {
R.drawable.expanded ,
R.drawable.expanded ,
R.drawable.expanded
};
//UnExpand Button New Items
int[] unexpandbutton = {
R.drawable.ca_expand ,
R.drawable.ca_expand ,
R.drawable.ca_expand
};
//Titles New Items
String[] titles = {
sys_title1 ,
sys_title2 ,
sys_title3
};
//Description New Items
String[] Description = {
sys_descr1 ,
sys_descr2 ,
sys_descr3
};
for(int i = 0;i<titles.length && i < icons.length && i < Description.length && i < unexpandbutton.length && i < expandbutton.length ; i++)
{
itemsdata current = new itemsdata();
current.CatPic = icons[i];
current.title = titles[i];
current.Descr = Description[i];
current.expand_no = unexpandbutton[i];
current.Exapnd = expandbutton[i];
data.add(current);
}
return data;
}
}
Details Activity :
public class DetailsActivity extends AppCompatActivity{
TextView title;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.details);
title = (TextView)findViewById(R.id.details_title);
}
EDIT : I've made it, i have added a button which open the fragment, and passed the data, in the Adapter, but i want it via tab_1.java, not the Adapter, i mean i want to click on the item to open the fragment, not on a button, here a snap from my Adapter code ( i've added it in OnBindViewHolder )
I've setup a OnClick and implemented the Vew.setOnClick ..etc, but when i click the item, nothing happen.
#Override
public void onBindViewHolder(final MyRecycleViewHolder holder, int position) {
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent i = new Intent(v.getContext(),DetailsActivity.class);
v.getContext().startActivity(i);
}
});
//Referencing Data
final itemsdata currentobject = mdata.get(position);
//Referencing Items
holder.ProbTitle.setText(currentobject.title);
holder.ProbDescr.setText(currentobject.Descr);
holder.CategoryPic.setImageResource(currentobject.CatPic);
holder.ExpandButton.setImageResource(currentobject.Exapnd);
holder.ExpandNoButton.setImageResource(currentobject.expand_no);
//What Happen When You Click Expand Button .
holder.ExpandButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent i = new Intent(v.getContext(), DetailsActivity.class);
i.putExtra("TitleKey",holder.ProbTitle.getText().toString());
v.getContext().startActivity(i);
}
}
);
public static class MyRecycleViewHolder extends RecyclerView.ViewHolder
{
SwipeLayout swipeLayout;
//Defining Items .
TextView ProbTitle;
ImageButton ExpandButton;
TextView ProbDescr;
ImageButton ExpandNoButton;
ImageView CategoryPic;
/*
TextView Card_Star;
TextView Card_UnStar;
*/
TextView Card_Share;
//Referencing Resources
public MyRecycleViewHolder(final View itemView) {
super(itemView);
ProbTitle = (TextView) itemView.findViewById(R.id.prob_title);
CategoryPic = (ImageView) itemView.findViewById(R.id.cat_pic);
ProbDescr = (TextView) itemView.findViewById(R.id.prob_descr);
ExpandButton = (ImageButton) itemView.findViewById(R.id.expand_button);
ExpandNoButton = (ImageButton) itemView.findViewById(R.id.expand_no_button);
/*
Card_Star = (TextView) itemView.findViewById(R.id.card_star);
Card_UnStar = (TextView) itemView.findViewById(R.id.card_unstar);
*/
Card_Share = (TextView) itemView.findViewById(R.id.card_share);
swipeLayout = (SwipeLayout) itemView.findViewById(R.id.swipe);
}

create an Interface inside your adapter containing methods. And while implementing your Adapter, those methods will be implemented in your activity and you can perform whatever action you want.
public class Adapter extends RecyclerView.Adapter<MyRecycleViewHolder> {
public interface Callbacks {
public void onButtonClicked(String titleKey);
}
private Callbacks mCallbacks;
public Adapter() {
}
#Override
public MyRecycleViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.layout_details, null);
return new MyRecycleViewHolder(v);
}
#Override
public void onBindViewHolder(final MyRecycleViewHolder holder, final int i) {
holder.ExpandButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (mCallbacks != null) {
mCallbacks.onButtonClicked(holder.ProbTitle.getText().toString());
}
}
});
}
#Override
public int getItemCount() {
return;
}
public void setCallbacks(Callbacks callbacks) {
this.mCallbacks = callbacks;
}
}

you may try do this on your onItemClick()
Intent i = new Intent(view.getContext(), DetailsActivity.class);
i.putExtra("title", yourTitle);
i.putExtra("description", yourDescription);
view.getContext().startActivity(i);
and when oncreate in your DetailActivity,do this
String title = getIntent().getStringExtra("title");
String description = getIntent().getStringExtra("description");
so you can pass title and description to DetailActivity

IMO, you implement setOnClickListener inside Adapter of RecyclerView. You can refer to my following sample code, then apply its logic to your code. Hope it helps!
public class MyRVAdapter extends RecyclerView.Adapter<MyRVAdapter.ViewHolder> {
Context mContext;
List<String> mStringList;
public MyRVAdapter(Context mContext, List<String> mStringList) {
this.mContext = mContext;
this.mStringList = mStringList;
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.cardview, parent, false);
v.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
TextView textView1 = (TextView) v.findViewById(R.id.textView1);
TextView textView2 = (TextView) v.findViewById(R.id.textView2);
Bundle bundle = new Bundle();
bundle.putString("key1", textView1.getText().toString());
bundle.putString("key2", textView2.getText().toString());
passToAnotherActivity(bundle);
}
});
return new ViewHolder(v);
}
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
// do something...
}
#Override
public int getItemCount() {
if (mStringList != null) {
return mStringList.size();
}
return 0;
}
private void passToAnotherActivity(Bundle bundle) {
if (mContext == null)
return;
if (mContext instanceof MainActivity) {
MainActivity activity = (MainActivity) mContext;
activity.passToAnotherActivity(bundle); // this method must be implemented inside `MainActivity`
}
}
public static class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
public ViewHolder(View itemView) {
super(itemView);
// do something...
}
#Override
public void onClick(View v) {
}
}
}

First of all make your "itemsdata" object to implement Parcelable. You can check it here . In your onItemClick method you pass the object to your Details activity using intent.putExtra("key",listOfDataItems.get(position));
In your DetailsActivity you can get your custom object with getParcelable("key")

All above methods worked, but kinda long, so this one worked for me :
Cardview cardview;
cardView = (CardView)itemView.findViewById(R.id.cv);
cardView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent i = new Intent (view.getContext(), DetailsActivity.class);
i.putExtra("TitleKey",ProbTitle.getText().toString());
i.putExtra("DescrKey",ProbDescr.getText().toString());
view.getContext().startActivity(i);
}
});
And in Details.java :
TextView title;
TextView Descr;
title = (TextView)findViewById(R.id.details_title);
Descr = (TextView)findViewById(R.id.details_descr);
String titleresult = result.getExtras().getString("TitleKey");
String Descrresult = result.getExtras().getString("DescrKey");
title.setText(titleresult);
Descr.setText(Descrresult);