Develop Reference

How can I show/hide a layout in the main activity from a RecyclerView in android studio java?

I have an activity which consists of a recycler view for generating buttons (from a different layout file) and a layout with elements for confirmation.
I want to make it so when I click on the button "NEW GAME" (in the Recyclerview class), the confirmationLayout (in the MainMenu Activity) shows. But I can't, can someone help me?
MainMenu Class
public class MainMenu extends AppCompatActivity {
private ImageView profileIcon;
private TextView username;
private RelativeLayout newGameConfirmationLayout;
private TextView yesButton, noButton;
private RecyclerView buttonRecyclerView;
private ButtonRecyclerAdapter adapter;
private DataHandler dataHandler;
private ArrayList<String> buttonNames = new ArrayList<>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_menu);
newGameConfirmationLayout = findViewById(R.id.newGameConfirmationLayout);
yesButton = findViewById(R.id.yesButton);
noButton = findViewById(R.id.noButton);
buttonRecyclerView = findViewById(R.id.buttonRecyclerView);
buttonRecyclerView.setLayoutManager(new LinearLayoutManager(MainMenu.this));
if(General.infoSaved){buttonNames.add("CONTINUE GAME");}
buttonNames.add("NEW GAME");
buttonNames.add("CHANGE USER");
buttonNames.add("PRACTICE");
buttonNames.add("EXERCISE LIST");
adapter = new ButtonRecyclerAdapter(buttonNames, MainMenu.this);
buttonRecyclerView.setAdapter(adapter);
yesButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startGame();
}
});
noButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
newGameConfirmationLayout.setVisibility(View.INVISIBLE);
}
});
}
private void startGame(){}
public void show_confirmationLayout(){
newGameConfirmationLayout.setVisibility(View.VISIBLE);
}
RecyclerView Class
public class ButtonRecyclerAdapter extends RecyclerView.Adapter<ButtonRecyclerAdapter.buttonHolder>{
private ArrayList<String> buttonNames;
private Context context;
public ButtonRecyclerAdapter(ArrayList<String> loginButtonNames, Context context) {
this.buttonNames = loginButtonNames;
this.context = context;
}
#NonNull
#Override
public buttonHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.button_block,parent,false);
return new buttonHolder(view);
}
#Override
public void onBindViewHolder(#NonNull buttonHolder holder, int position) {
holder.button.setText(buttonNames.get(position));
holder.button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String buttonName = holder.button.getText().toString();
switch (buttonName){
case "NEW GAME":
MainMenu mainMenu = new MainMenu();
mainMenu.show_confirmationLayout();
break;
}
}
});
}
#Override
public int getItemCount() {
return buttonNames.size();
}
public class buttonHolder extends RecyclerView.ViewHolder{
private Button button;
public buttonHolder(#NonNull View itemView) {
super(itemView);
button = itemView.findViewById(R.id.buttonblock);
}
}
}
I tried adding it as a class (as above) but I get the error that the layout is a null object / However when I try to write the ame line of code directly in the activity it works.

There's a method I personally use in my RecyclerView's Adapter and ViewHolder is to set the width and height of your item's ViewGroup to 0.
Here's the method you can add to your adapter class which takes item position that you want to hide:
public void hideFeedItem(int position){
RecyclerView.ViewHolder holder = getViewHolderAtPosition(position);
if(holder != null){
ViewGroup.LayoutParams params = holder.itemView.getLayoutParams();
params.height=0;
params.width= 0;
holder.itemView.setLayoutParams(params);
}
}
Where itemview is the root ViewGroup that should be already defined in your ViewHolder in your case should be buttonHolder.

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.

Passing data from RecyclerView.Adapter to fragment onClick

I'm trying to figure out how to get data from a clicked item in a RecyclerView to a listview in a Fragment. I can't seem to figure out how to do this, as I can't get my bundle to work.
I've tried various solutions offered here on Stackoverflow, but none of them have worked. I have managed to get the info from the recyclerview, but I am stuck trying to figure out how I can pass it to the fragment. Can someone please help me?
The Adapter class:
public class FoodAdapter extends RecyclerView.Adapter<FoodAdapter.ViewHolder> {
private Context context;
ArrayList<FoodActivity> list;
public FoodAdapter(ArrayList<FoodActivity> list){
this.list = list;
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.listview_item_food, parent, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull final ViewHolder holder, final int position) {
holder.foods.setText(list.get(position).getName());
holder.carbo.setText(list.get(position).getCarbohydrates());
holder.protein.setText(list.get(position).getProtein());
holder.fats.setText(list.get(position).getFats());
//Get items from recyclerview when user clicks them. Then send them to FoodFragment
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String foods = list.get(position).getName();
String carbo = list.get(position).getCarbohydrates();
String protein = list.get(position).getProtein();
String fats = list.get(position).getFats();
Toast.makeText(v.getContext(), "test: " + foods, Toast.LENGTH_SHORT).show();
}
});
}
#Override
public int getItemCount() {
return list.size();
}
class ViewHolder extends RecyclerView.ViewHolder {
TextView foods, carbo, fats, protein;
public ViewHolder(View itemView) {
super(itemView);
carbo = itemView.findViewById(R.id.carbo);
protein = itemView.findViewById(R.id.protein);
fats = itemView.findViewById(R.id.fats);
foods = itemView.findViewById(R.id.food);
}
}
}
The Fragment where the data comes from:
public class TrackingFragment extends Fragment {
DatabaseReference databaseReference;
ArrayList<FoodActivity> list;
RecyclerView recyclerView;
SearchView searchView;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_tracking, container, false);
databaseReference = FirebaseDatabase.getInstance().getReference().child("foods");
recyclerView = view.findViewById(R.id.rv);
searchView = view.findViewById(R.id.searchFood);
return view;
}
#Override
public void onStart() {
super.onStart();
if(databaseReference != null){
databaseReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
if(dataSnapshot.exists()){
list = new ArrayList<>();
for(DataSnapshot ds : dataSnapshot.getChildren()){
list.add(ds.getValue(FoodActivity.class));
}
FoodAdapter adapter = new FoodAdapter(list);
recyclerView.setAdapter(adapter);
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Toast.makeText(getActivity(), databaseError.getMessage(), Toast.LENGTH_SHORT).show();
}
});
}
if(searchView != null){
searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
#Override
public boolean onQueryTextSubmit(String query) {
return false;
}
#Override
public boolean onQueryTextChange(String newText) {
search(newText);
return true;
}
});
}
}
private void search(String str){
ArrayList<FoodActivity> searchList = new ArrayList<>();
for(FoodActivity object : list){
if(object.getName().toLowerCase().contains(str.toLowerCase())){
searchList.add(object);
}
}
FoodAdapter foodAdapter = new FoodAdapter(searchList);
recyclerView.setAdapter(foodAdapter);
}
}
And the class where it needs to go:
public class FoodFragment extends Fragment {
ImageButton addFood;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_food, container, false);
addFood = view.findViewById(R.id.addFood);
addFood.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
FragmentTransaction fr = getFragmentManager().beginTransaction();
fr.replace(R.id.fragment_container, new TrackingFragment());
fr.addToBackStack(null).commit();
}
});
return view;
}
}

The most simple is to add variables you need to your activity, set their values with onClick() and then retrieve data in other fragment:
in activity:
String foods;
public String getFoods() {
return foods;
}
public void setFoods(String foods) {
this.foods = foods;
}
in adapter:
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
((YourActivity)getActivity()).setFoods("Any value");
}
});
in destination fragment:
String foods = ((YourActivity)getActivity()).getFoods();

Add an interface to your adapter as follow
public class FoodAdapter extends RecyclerView.Adapter<FoodAdapter.ViewHolder> {
interface OnClickListener {
void onClick(FoodActivity clickedItem);
}
private OnClickListener mCallback;
private ArrayList<FoodActivity> list;
public FoodAdapter(ArrayList<FoodActivity> list){
this.list = list;
}
public void setOnClickListener(OnClickListener callback) {
mCallback = callback;
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.listview_item_food, parent, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull final ViewHolder holder, final int position) {
holder.foods.setText(list.get(position).getName());
holder.carbo.setText(list.get(position).getCarbohydrates());
holder.protein.setText(list.get(position).getProtein());
holder.fats.setText(list.get(position).getFats());
//Get items from recyclerview when user clicks them. Then send them to FoodFragment
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (mCallback != null)
mCallback.onClick(list.get(position));
}
});
}
#Override
public int getItemCount() {
return list.size();
}
class ViewHolder extends RecyclerView.ViewHolder {
TextView foods, carbo, fats, protein;
public ViewHolder(View itemView) {
super(itemView);
carbo = itemView.findViewById(R.id.carbo);
protein = itemView.findViewById(R.id.protein);
fats = itemView.findViewById(R.id.fats);
foods = itemView.findViewById(R.id.food);
}
}
}

Android sometimes is a little complicated, when it involves the full stack:
01 RecyclerView Adapter
/** 01. Some Adapter */
public class SomeAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private WeakReference<Context> mContext;
/** Constructor */
public SomeAdapter(#NonNull Context context) {
this.mContext = new WeakReference<>(context);
}
#NonNull
protected Context getContext() {
return this.mContext.get();
}
/** Call to Activity from within the adapter. */
private void someMethod() {
SomeActivity activity = (SomeActivity) getContext();
synchronized(activity) {activity.showLoginDialog();}
}
}
02 AppCompatActivity
/** 02. Some Activity */
public class SomeActivity extends AppCompatActivity {
#Nullable
private BaseFragment currentFragment = null;
/** Constructor */
public SomeActivity() {}
public void setCurrentFragment(Fragment fragment) {
this.currentFragment = fragment;
}
/** Call to the current Fragment. */
public void someMethod() {
if (currentFragment != null) {
currentFragment.someMethod();
}
}
}
03 Fragment
/** Some Fragment */
public class SomeFragment extends Fragment {
/** Constructor */
public SomeFragment() {}
#Override
public void onAttach(#NonNull Context context) {
super.onAttach(context);
((BaseActivity) context).setCurrentFragment(this);
}
#Override
public void onDetach() {
super.onDetach();
((BaseActivity) getActivity()).setCurrentFragment(this);
}
}

To get your data from FoodAdapter to TrackingFragment, you can add TrackingFragment (or an interface it implements, ideally) as a parameter to the FoodAdapter constructor, then use that instance to forward your ViewHolder clicks to TrackingFragment for handling.
To get your data from TrackingFragment to FoodFragment, use the setTargetFragment/onActivityResult pattern for fragment <-> fragment communication. This answer has an example: https://stackoverflow.com/a/13733914/3238938

Problems calling notifyDataSetChange in RecyclerViewHolder

I am having problems updating my RecyclerView with new data. If I press a confirmation button on a CardView in the first tab, the card should get added to the second tab but it won't update it there until I rotate the screen. I get the data for the card from reading a text file. Please advise me how to call the notifyDataSetChange method after I have added the new data to my text file. I have tried everything and all I get is NullPointerExceptions. The RecyclerViews are in fragments and I use FragementStatePagerAdapter.
I'll put some of my classes here. Ask if you need more information.
RecyclerViewAdapter.java
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewHolder> {
private List<String> mListTitle;
private List<String> mListDesc;
private List<String> mListPoints;
private List<String> mListDates;
private String fragment_tag;
public RecyclerViewAdapter() {
}
public RecyclerViewAdapter(List<List<String>> super_list, String tag) {
this.mListTitle = super_list.get(0);
this.mListDesc = super_list.get(1);
this.mListPoints = super_list.get(2);
this.mListDates = super_list.get(3);
fragment_tag = tag;
}
#Override
public RecyclerViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
return new RecyclerViewHolder(inflater, parent, fragment_tag);
}
#Override
public void onBindViewHolder(RecyclerViewHolder holder, int position) {
holder.mTitleText.setText(mListTitle.get(position));
holder.mDescText.setText(mListDesc.get(position));
holder.mPointsText.setText(mListPoints.get(position));
if (fragment_tag.equals("completed")) {
holder.mDateText.setText(mListDates.get(position));
}
}
#Override
public int getItemCount() {
return mListTitle.size();
}
}
class RecyclerViewHolder extends RecyclerView.ViewHolder {
RecyclerView recyclerView;
RecyclerViewAdapter mAdapter;
public TextView mTitleText, mDescText, mDateText, mPointsText, popupTitle;
public Button mConfButton, popCancelBtn, popAcceptBtn;
public RecyclerViewHolder(View itemView) {
super(itemView);
}
public RecyclerViewHolder(final LayoutInflater inflater, final ViewGroup container, String tag) {
// Inflating the card layout depending on the tag parameter.
super(inflater.inflate
((tag.equals("challenges")) ? R.layout.card_view_chall : R.layout.card_view_comp, container,
false));
mTitleText = itemView.findViewById(R.id.title_holder);
mDescText = itemView.findViewById(R.id.desc_holder);
mPointsText = itemView.findViewById(R.id.points_holder);
mDateText = itemView.findViewById(R.id.date_holder);
if (tag.equals("challenges")) {
mConfButton = itemView.findViewById(R.id.card_conf_button);
mConfButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
// Setting the layout inflater for popup window.
LayoutInflater pInflater = (LayoutInflater) itemView.getContext().getSystemService(LAYOUT_INFLATER_SERVICE);
ViewGroup container1 = (ViewGroup) pInflater.inflate(R.layout.confirmation_popup, null);
final PopupWindow popupWindow = new PopupWindow(container1, 700, 600, true);
popupTitle = container1.findViewById(R.id.popuptext);
popAcceptBtn = container1.findViewById(R.id.accept_button);
popCancelBtn = container1.findViewById(R.id.cancel_button);
popupTitle.setText(mTitleText.getText().toString());
// Dismisses the popup window
popCancelBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
popupWindow.dismiss();
}
});
// Click listener for dialog accept button.
popAcceptBtn.setOnClickListener(new View.OnClickListener() {
String date;
#Override
public void onClick(View view) {
List<String> list = new ArrayList<>();
list.add(mTitleText.getText().toString());
list.add(mDescText.getText().toString());
list.add(mPointsText.getText().toString());
list.add(date = new SimpleDateFormat("dd-MM-yyyy", Locale.getDefault()).format(new Date()));
// Saving data from current card into the completed challenges list.
TempDataReader reader = new TempDataReader(itemView.getContext());
new TempDataReader(itemView.getContext()).saveFile(list);
// I want to notify the dataset change here if possible!
popupWindow.dismiss();
}
});
popupWindow.showAtLocation(itemView, Gravity.CENTER, 25, 100);
}
});
}
}
}
SectionsPagerAdapter.java
public class SectionsPagerAdapter extends FragmentStatePagerAdapter{
private ViewPager viewPager;
private final List<Fragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
public void addFragment(Fragment fragment, String title){
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public CharSequence getPageTitle(int position) {
return mFragmentTitleList.get(position);
}
#Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
#Override
public Fragment getItem(int position) {
return mFragmentList.get(position);
}
#Override
public int getCount() {
return mFragmentList.size();
}
#Override
public void notifyDataSetChanged() {
super.notifyDataSetChanged();
}
}
CompletedFragment.java
public class CompletedFragment extends Fragment {
RecyclerView recyclerView;
RecyclerViewAdapter adapter;
public Fragment newInstance() {
return new CompletedFragment();
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.completed_fragment, container, false);
recyclerView = view.findViewById(R.id.completed_frag);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
TempDataReader reader = new TempDataReader(getActivity());
List<List<String>> super_list = reader.readCompFile();
if(super_list == null || super_list.size() < 1){
return null;
} else{
adapter = new RecyclerViewAdapter(super_list,"completed");
recyclerView.setAdapter(adapter);
return view;
}
}
}
EDIT:
Added the code for the second fragment, which is the one that should be updated after the onClick at RecyclerViewHolder-class.

You have to add a function in your adapter for adding data:
public void addData(String title, String desc, String point, String date) {
this.mListTitle.add(title);
this.mListDesc.add(desc);
this.mListPoints.add(point);
this.mListDates.add(date);
notifyDataSetChanged();
}
If you want to enable animations call notifyItemInserted() instead of notifyDataSetChanged();
It is important that you add a String to every list because in your onBindViewHolder() you get the item to display from every list with list.get(position). Otherwise you'll get a IndexOutOfBoundsException.

You can create an interface and use as a callback. Send it as a parameter of the RecyclerViewAdapter and then to your RecyclerViewHolder. When the item should be added you call the callback that will get you back to your fragment. There you can read the file again and call notifyDataSetChanged.
I know i explain pretty bad so i will try to change your code so that it does what i said:
this will be your RecyclerViewAdapter:
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewHolder> {
private List<String> mListTitle;
private List<String> mListDesc;
private List<String> mListPoints;
private List<String> mListDates;
private String fragment_tag;
private Runnable callback;
public RecyclerViewAdapter() {
}
public RecyclerViewAdapter(List<List<String>> super_list, String tag, Runnable callBack) {
//add the callback here(Runnable) and save it into a local variable
this.callback=callback;
this.mListTitle = super_list.get(0);
this.mListDesc = super_list.get(1);
this.mListPoints = super_list.get(2);
this.mListDates = super_list.get(3);
fragment_tag = tag;
}
#Override
public RecyclerViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
return new RecyclerViewHolder(inflater, parent, fragment_tag, callback);
//send the callback to your viewHolder
}
#Override
public void onBindViewHolder(RecyclerViewHolder holder, int position) {
holder.mTitleText.setText(mListTitle.get(position));
holder.mDescText.setText(mListDesc.get(position));
holder.mPointsText.setText(mListPoints.get(position));
if (fragment_tag.equals("completed")) {
holder.mDateText.setText(mListDates.get(position));
}
}
#Override
public int getItemCount() {
return mListTitle.size();
}
}
class RecyclerViewHolder extends RecyclerView.ViewHolder {
RecyclerView recyclerView;
RecyclerViewAdapter mAdapter;
public TextView mTitleText, mDescText, mDateText, mPointsText, popupTitle;
public Button mConfButton, popCancelBtn, popAcceptBtn;
public RecyclerViewHolder(View itemView) {
super(itemView);
}
public RecyclerViewHolder(final LayoutInflater inflater, final ViewGroup container, String tag, Runnable callback) {
//ADD the callback to the parameters list here
// Inflating the card layout depending on the tag parameter.
super(inflater.inflate
((tag.equals("challenges")) ? R.layout.card_view_chall : R.layout.card_view_comp, container,
false));
mTitleText = itemView.findViewById(R.id.title_holder);
mDescText = itemView.findViewById(R.id.desc_holder);
mPointsText = itemView.findViewById(R.id.points_holder);
mDateText = itemView.findViewById(R.id.date_holder);
if (tag.equals("challenges")) {
mConfButton = itemView.findViewById(R.id.card_conf_button);
mConfButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
// Setting the layout inflater for popup window.
LayoutInflater pInflater = (LayoutInflater) itemView.getContext().getSystemService(LAYOUT_INFLATER_SERVICE);
ViewGroup container1 = (ViewGroup) pInflater.inflate(R.layout.confirmation_popup, null);
final PopupWindow popupWindow = new PopupWindow(container1, 700, 600, true);
popupTitle = container1.findViewById(R.id.popuptext);
popAcceptBtn = container1.findViewById(R.id.accept_button);
popCancelBtn = container1.findViewById(R.id.cancel_button);
popupTitle.setText(mTitleText.getText().toString());
// Dismisses the popup window
popCancelBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
popupWindow.dismiss();
}
});
// Click listener for dialog accept button.
popAcceptBtn.setOnClickListener(new View.OnClickListener() {
String date;
#Override
public void onClick(View view) {
List<String> list = new ArrayList<>();
list.add(mTitleText.getText().toString());
list.add(mDescText.getText().toString());
list.add(mPointsText.getText().toString());
list.add(date = new SimpleDateFormat("dd-MM-yyyy", Locale.getDefault()).format(new Date()));
// Saving data from current card into the completed challenges list.
TempDataReader reader = new TempDataReader(itemView.getContext());
new TempDataReader(itemView.getContext()).saveFile(list);
// I want to notify the dataset change here if possible!
//call the callback
callback.run();
popupWindow.dismiss();
}
});
popupWindow.showAtLocation(itemView, Gravity.CENTER, 25, 100);
}
});
}
}
}
And this will be your fragment:
public class CompletedFragment extends Fragment {
RecyclerView recyclerView;
RecyclerViewAdapter adapter;
public Fragment newInstance() {
return new CompletedFragment();
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.completed_fragment, container, false);
recyclerView = view.findViewById(R.id.completed_frag);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
TempDataReader reader = new TempDataReader(getActivity());
List<List<String>> super_list = reader.readCompFile();
if(super_list == null || super_list.size() < 1){
return null;
} else{
adapter = new RecyclerViewAdapter(super_list,"completed", new Runnable() {
#Override
public void run() {
//here read the list again and call notifyDataSetChanged on your recycler
}
});
);
recyclerView.setAdapter(adapter);
return view;
}
}
}
Hope it helps and it works for you. If i did anything wrong, let me know, i can't run the code right now so...
edited, i forgot to add code in the callback

Item removed from ArrayList, but notifyDataSetChanged() only deletes the bottom item

I have a recycler view, with an ArrayList from custom objects.
Each row has a delete button, when clicked the item is deleted from the recyclerview.
Now the delete button works, and deletes the correct item from the arraylist, however when the items are displayed again in the list, only the bottom item is deleted, and the item which was really deleted from the list stays there.
Its really weird, and I cannot figure out why?
I manage the deleted item from the activity, here is the code of the activity:
public class ManageExerciseActivity extends AppCompatActivity {
private static final String TAG = "999.OffLimitsActivity";
private RecyclerView exerciseRecyclerView;
private ExerciseManageAdapter exerciseAdapter;
public ArrayList<Exercise> exerciseList;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_manage_exercise);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(ManageExerciseActivity.this, AddExerciseActivity.class);
startActivity(intent);
}
});
fab.setImageBitmap(textAsBitmap("ADD", 40, Color.WHITE));
exerciseList = new ArrayList<>();
getSupportActionBar().setTitle("Manage my exercises");
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setDisplayShowHomeEnabled(true);
exerciseRecyclerView = (RecyclerView) findViewById(R.id.exercise_manage_recycler_view);
exerciseAdapter = new ExerciseManageAdapter(exerciseList);
exerciseAdapter.setOnItemClickListener(new ExerciseManageAdapter.ClickListener() {
#Override
public void onItemClick(final int position, final View v) {
Log.d(TAG, "onItemClick pos = " + position);
// custom dialog
AlertDialog.Builder builder = new AlertDialog.Builder(ManageExerciseActivity.this);
builder.setMessage("Do you wish to delete this exercise?")
.setPositiveButton(R.string.yes, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
String itemRemoved = exerciseList.get(position).getNameOfExercise();
exerciseList.remove(position);
exerciseAdapter.notifyDataSetChanged();
Snackbar.make(v, itemRemoved + " deleted", Snackbar.LENGTH_LONG)
.setAction("Undo", null).show();
}
})
.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// User cancelled the dialog
}
});
// Create the AlertDialog object and return it
builder.create();
builder.show();
}
});
exerciseRecyclerView.setAdapter(exerciseAdapter);
exerciseRecyclerView.setLayoutManager(new LinearLayoutManager(this));
}
and here is the adapter:
public class ExerciseManageAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private static ClickListener clickListener;
public ImageView exerciseItemIcon;
public TextView exerciseNameTextView;
public TextView exerciseDurationTextView;
public TextView exerciseTimesRemainingTextView;
public ImageView deleteImageView;
ArrayList<Exercise> exerciseArrayList = new ArrayList<>();
public ExerciseManageAdapter(ArrayList<Exercise> exerciseArrayList) {
this.exerciseArrayList = exerciseArrayList;
}
public interface ClickListener {
void onItemClick(int position, View v);
}
class ExerciseViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
public ExerciseViewHolder(View view) {
super(view);
// view.setOnClickListener(this);
exerciseNameTextView = (TextView)view.findViewById(R.id.exercise_manage_name_textView);
exerciseDurationTextView = (TextView)view.findViewById(R.id.exercise_manage_duration_textview);
exerciseTimesRemainingTextView = (TextView)view.findViewById(R.id.exercise_manage_times_remaining);
exerciseItemIcon = (ImageView)view.findViewById(R.id.exercise_manage_item_icon);
deleteImageView = (ImageView)view.findViewById(R.id.delete_exercise_button);
deleteImageView.setOnClickListener(this);
}
#Override
public void onClick(View v) {
clickListener.onItemClick(getAdapterPosition(), v);
}
}
public void setOnItemClickListener(ClickListener clickListener) {
ExerciseManageAdapter.clickListener = clickListener;
}
#Override
public int getItemViewType(int position) {
return position;
}
#Override
public int getItemCount() {
return exerciseArrayList.size();
}
#Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext())
.inflate(R.layout.exercise_manage_item_row, parent, false);
return new ExerciseViewHolder(itemView);
}
#Override
public void onBindViewHolder(final RecyclerView.ViewHolder holder, final int position) {
ExerciseViewHolder exerciseViewHolder = (ExerciseViewHolder) holder;
exerciseNameTextView.setText(exerciseArrayList.get(position).getNameOfExercise());
exerciseDurationTextView.setText(exerciseArrayList.get(position).getDurationOfExercise());
exerciseTimesRemainingTextView.setText(exerciseArrayList.get(position).getTimesPerWeek() + " times a week");
exerciseItemIcon.setImageResource(exerciseArrayList.get(position).getExerciseIcon());
}
}
Thanks

try this.!
notifyItemRemoved(position);
notifyItemRangeChanged(position, mData.size());