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How to update listview in Fragment with custom adapter

I am giving product id with barcode scanner. I can add product to listView but when i try to increase or decrease amount of the product. It doesn't update UI. I used Toast message to see weather list is updated, it updates list but doesn't update UI
I have tried to use runOnUiThread() but i couldn't find any solution. How to update UI can you please help me
custom_lisView_row
BaseActivity which keeps MainFragment on it
public class BaseActivity extends AppCompatActivity {
public static final String MAIN_FRAGMENT = "mainFragment";
public static final String PRODUCTS = "products";
FragmentManager fragmentManager;
Dialog dialog ;
public static ArrayList<MyProduct> myProductList = new ArrayList<>();
public static MyTablet myTablet = new MyTablet();
Activity mActivity;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_base);
//Initialize fragment manager
fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.fl_BaseActivity, new MainFragment()).commit();
//Create database
mDatabase = FirebaseDatabase.getInstance().getReference();
dialog = new Dialog(this);
//Runs when i enter product id
initScanner();
}
public void updateMyProductList(MyProduct myProduct){
for(int i= 0 ; i< myProductList.size() ; i++ ){
MyProduct temp = myProductList.get(i);
if (temp.getId().equals(myProduct.getId())) {
temp.setAmount(temp.getAmount() + myProduct.getAmount());
myProductList.set(i, temp);
return;
}
}
myProductList.add(myProduct);
updateMainFragment();
}
private void initScanner() {
mDatabase.child(PRODUCTS).child(finalData).get().addOnCompleteListener(new OnCompleteListener<DataSnapshot>() {
#Override
public void onComplete(#NonNull Task<DataSnapshot> task) {
MyProduct myProduct = task.getResult().getValue(MyProduct.class);
myProduct.setAmount(1);
dialog.setContentView(R.layout.custom_product_dialog);
dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
dialog.setCancelable(false);
TextView tv_addBasket_product_dialog = dialog.findViewById(R.id.tv_addBasket_product_dialog);
tv_addBasket_product_dialog.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
updateMyProductList(myProduct);
dialog.dismiss();
}
});
dialog.show();
}
};
}
public void updateMainFragment() {
if (isExist(MAIN_FRAGMENT)) {
Fragment fragment = findFragment(MAIN_FRAGMENT);
((MainFragment) fragment).updateMyList();
}
}
//Add fragments to BaseActivity
public void addFragments(Fragment fragment, String tag) {
fragmentManager.beginTransaction().add(R.id.fl_BaseActivity, fragment, tag).commit();
}
//Replace fragments to BaseActivity
public void replaceFragments(Fragment fragment, String tag) {
fragmentManager.beginTransaction().replace(R.id.fl_BaseActivity, fragment, tag).commit();
}
//Remove fragment from BaseActivity
public void removeFragment(String tag) {
Fragment fragmentB = fragmentManager.findFragmentByTag(tag);
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
if (fragmentB != null) {
fragmentTransaction.remove(fragmentB);
fragmentTransaction.commit();
}
}
// finds fragment and returns it
// It may return null first check fragment is exist. use isExist() method
public Fragment findFragment(String tag) {
Fragment fragment = fragmentManager.findFragmentByTag(tag);
return fragment;
}
//Check fragment exist in BaseActivity
public boolean isExist(String tag) {
Fragment fragmentB = fragmentManager.findFragmentByTag(tag);
if (fragmentB != null) {
return true;
}
return false;
}
}
MainFragment
public class MainFragment extends Fragment {
ListView lv_MainFragment;
public MyProductListAdapter myListAdapter;
public static ArrayList<MyProduct> myProductList;
Activity mActivity;
#Override
public void onAttach(Context context) {
super.onAttach(context);
mActivity = getActivity();
}
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
myProductList = BaseActivity.myProductList;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_main, container, false);
lv_MainFragment = view.findViewById(R.id.lv_MainFragment);
myListAdapter = new MyProductListAdapter(mActivity.getApplicationContext(), R.layout.custom_product_list_row, myProductList);
lv_MainFragment.setAdapter(myListAdapter);
return view;
}
public void updateMyList() {
myProductList = BaseActivity.myProductList;
myListAdapter.notifyDataSetChanged();
}
}
MyProductListAdapter
public class MyProductListAdapter extends ArrayAdapter<MyProduct> {
private Context mContext;
private ArrayList<MyProduct> list;
AppCompatButton acb_DecreaseAmount_productListRow, acb_IncreaseAmount_productListRow;
public MyProductListAdapter(Context context, int resource, ArrayList<MyProduct> objects) {
super(context, resource, objects);
this.mContext = context;
this.list = objects;
}
#Override
public View getView(int position, #Nullable View convertView, #NonNull ViewGroup parent) {
View view = convertView;
if (view == null) {
LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view = inflater.inflate(R.layout.custom_product_list_row, parent, false);
tv_ProductAmount_productListRow = view.findViewById(R.id.tv_ProductAmount_productListRow);
acb_DecreaseAmount_productListRow = view.findViewById(R.id.acb_DecreaseAmount_productListRow);
acb_IncreaseAmount_productListRow = view.findViewById(R.id.acb_IncreaseAmount_productListRow);
tv_ProductAmount_productListRow.setText(String.valueOf(list.get(position).getAmount()));
acb_IncreaseAmount_productListRow.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
double productPrice = list.get(position).getPrice();
int productAmount = list.get(position).getAmount();
productAmount++;
list.get(position).setAmount(productAmount);
Toast.makeText(mContext, String.valueOf(productAmount), Toast.LENGTH_SHORT).show();
tv_ProductAmount_productListRow.setText(String.valueOf(list.get(position).getAmount()));
}
});
acb_DecreaseAmount_productListRow.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
int productAmount = list.get(position).getAmount();
if (productAmount > 1) {
double productPrice = list.get(position).getPrice();
productAmount--;
list.get(position).setAmount(productAmount);
Toast.makeText(mContext, String.valueOf(productAmount), Toast.LENGTH_SHORT).show();
tv_ProductAmount_productListRow.setText(String.valueOf(list.get(position).getAmount()));
}
}
});
}
return view;
}
}

Hej Metehan,
your use case sounds perfect for a RecyclerView with a ListAdapter. You just submit a new list of products to the adapter and it will handle the updating and notifying for you.

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.

Android Studio Recycler View Remove Item [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Android Studio Delete Items from Recycler View and List [duplicate]
(2 answers)
Closed 2 years ago.
I am trying to remove Items from my recycler view. Every time I click on an item in my recycler view it provides me with this error.
java.lang.NullPointerException: Attempt to invoke virtual method 'void uk.edu.le.co2103.myrecipebook.RecipeListAdapter.removeItem(int, java.util.List)' on a null object reference
I have made sure that my list has been initalized and used a log to ensure that both position and the list have values in them.
List: [uk.edu.le.co2103.myrecipebook.Recipe#f4d5298, uk.edu.le.co2103.myrecipebook.Recipe#ca6aaf1]
D/MAIN ACTIVITY: Index: 0
Here is my Main Activity code
public class MainActivity extends AppCompatActivity implements
RecipeListAdapter.OnItemClickListener {
private static final String TAG = "MAIN ACTIVITY";
private static final int RESULT_UPDATED = 300;
private RecipeViewModel mRecipeViewModel;
public static final int NEW_WORD_ACTIVITY_REQUEST_CODE = 1;
public String Name;
public String Ingredients;
public String Method;
private RecipeListAdapter mAdapter;
private RecipeDao recDao;
Menu menu;
List<Recipe> recipesList = new ArrayList<>();
ListView search_items;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
RecyclerView recyclerView = findViewById(R.id.recyclerview);
RecipeListAdapter mAdapter = new RecipeListAdapter(this);
recyclerView.setAdapter(mAdapter);
mAdapter.setOnItemClickListener(MainActivity.this);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
mRecipeViewModel = new ViewModelProvider(this).get(RecipeViewModel.class);
Log.d(TAG, "SIZE OF LIST: "+ recipesList);
mRecipeViewModel.getAllRecipes().observe(this, new Observer<List<Recipe>>() {
#Override
public void onChanged(#Nullable final List<Recipe> recipes) {
// Update the cached copy of the words in the adapter.
int size = mAdapter.getItemCount();
Log.d(TAG, "List of List : " + recipes);
recipesList= recipes;
mAdapter.setWords(recipes);
}
});
FloatingActionButton fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(MainActivity.this, AddRecipeActivity.class);
startActivityForResult(intent, NEW_WORD_ACTIVITY_REQUEST_CODE);
}
});
}
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == NEW_WORD_ACTIVITY_REQUEST_CODE && resultCode == RESULT_OK) {
ArrayList<String> rData = data.getStringArrayListExtra(AddRecipeActivity.EXTRA_REPLY);
String name = rData.get(0);
String ingredients = rData.get(1);
String method = rData.get(2);
Recipe recipe = new Recipe(name, ingredients, method);
RecipeViewModel.insert(recipe);
}
else {
Toast.makeText(
getApplicationContext(),
R.string.empty_not_saved,
Toast.LENGTH_LONG).show();
}
}
#Override
public void onItemClick(int position, View view) {
Log.d(TAG, "onItemClick Position: " + position);
AlertDialog.Builder alertDialog = new AlertDialog.Builder(this);
alertDialog.setTitle("Edit or Delete...");
alertDialog.setPositiveButton("Edit", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialogInterface, int i) {
recipesList.get(position); //clicked item
Intent update = new Intent(MainActivity.this, UpdateRecipeActivity.class);
update.putExtra("Name", recipesList.get(position).getName()); //
update.putExtra("Ingredients", recipesList.get(position).getIngredients());
update.putExtra("Method", recipesList.get(position).getMethod());
startActivity(update);
}
});
alertDialog.setNegativeButton("Delete", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialogInterface, int i) {
//Delete
Log.d(TAG, "List: " + recipesList);
Log.d(TAG, "Index: " + position);
int removeIndex = position;
recipesList.remove(removeIndex);
}
});
alertDialog.setNeutralButton("Cancel", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialogInterface, int i) {
}
});
alertDialog.show();
}
Here is my adapter code
public class RecipeListAdapter extends
RecyclerView.Adapter<RecipeListAdapter.RecipeViewHolder> {
private static final String TAG = "ADAPTER";
private OnItemClickListener mListener;
public interface OnItemClickListener{
void onItemClick(int position, View view);
}
public void setOnItemClickListener(OnItemClickListener listener){
mListener = listener;
}
class RecipeViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
private final TextView recipeItemView;
private RecipeViewHolder(View itemView) {
super(itemView);
recipeItemView = itemView.findViewById(R.id.textView);
itemView.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v){
if (mListener != null){
int position = getAdapterPosition();
if (position != RecyclerView.NO_POSITION){
mListener.onItemClick(position, v);
}
}
}
});
}
#Override
public void onClick(View view) {
mListener.onItemClick(getAdapterPosition(), view);
}
}
private final LayoutInflater mInflater;
private List<Recipe> mRecipes; // Cached copy of words
RecipeListAdapter(Context context) {
mInflater = LayoutInflater.from(context);
}
#Override
public RecipeViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = mInflater.inflate(R.layout.recyclerview_item, parent, false);
return new RecipeViewHolder(itemView);
}
#Override
public void onBindViewHolder(RecipeViewHolder holder, int position) {
if (mRecipes != null) {
Recipe current = mRecipes.get(position);
holder.recipeItemView.setText(current.getName());
} else {
// Covers the case of data not being ready yet.
holder.recipeItemView.setText("No Recipes");
}
}
void setWords(List<Recipe> recipes){
mRecipes = recipes;
notifyDataSetChanged();
}
public void deleteItem(final int position) {
mRecipes.remove(position);
notifyItemRemoved(position);
}
#Override
public int getItemCount() {
if (mRecipes != null)
return mRecipes.size();
else return 0;
}
public interface OnNoteListener{}
}
Here is the full error output
2020-04-02 15:27:30.553 5522-5522/uk.edu.le.co2103.myrecipebook E/AndroidRuntime: FATAL EXCEPTION: main
Process: uk.edu.le.co2103.myrecipebook, PID: 5522
java.lang.NullPointerException: Attempt to invoke virtual method 'void uk.edu.le.co2103.myrecipebook.RecipeListAdapter.deleteItem(int)' on a null object reference
at uk.edu.le.co2103.myrecipebook.MainActivity$4.onClick(MainActivity.java:133)
at androidx.appcompat.app.AlertController$ButtonHandler.handleMessage(AlertController.java:167)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:216)
at android.app.ActivityThread.main(ActivityThread.java:7464)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:549)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:955)

I changed your adapter. I found some problems :
public class RecipeListAdapter extends
RecyclerView.Adapter<RecipeListAdapter.RecipeViewHolder> {
private static final String TAG = "ADAPTER";
private OnItemClickListener mListener;
public interface OnItemClickListener{
void onItemClick(int position, View view);
}
public void setOnItemClickListener(OnItemClickListener listener){
mListener = listener;
}
class RecipeViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
private final TextView recipeItemView;
private RecipeViewHolder(View itemView) {
super(itemView);
recipeItemView = itemView.findViewById(R.id.textView);
itemView.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v){
if (mListener != null){
int position = getAdapterPosition();
if (position != RecyclerView.NO_POSITION){
mListener.onItemClick(position, v);
}
}
}
});
}
#Override
public void onClick(View view) {
mListener.onItemClick(getAdapterPosition(), view);
}
}
private final LayoutInflater mInflater;
private List<Recipe> mRecipes; // Cached copy of words
RecipeListAdapter(Context context) {
mInflater = LayoutInflater.from(context);
}
#Override
public RecipeViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = mInflater.inflate(R.layout.recyclerview_item, parent, false);
return new RecipeViewHolder(itemView);
}
#Override
public void onBindViewHolder(RecipeViewHolder holder, int position) {
if (mRecipes != null) {
Recipe current = mRecipes.get(position);
holder.recipeItemView.setText(current.getName());
} else {
// Covers the case of data not being ready yet.
holder.recipeItemView.setText("No Recipes");
}
}
void setWords(List<Recipe> recipes){
mRecipes = recipes;
notifyDataSetChanged();
}
public void deleteItem(final int position) {
mRecipes.remove(position);
notifyItemRemoved(position);
}
#Override
public int getItemCount() {
if (mRecipes != null)
return mRecipes.size();
else return 0;
}
public interface OnNoteListener{}
}

you can use it
public void deleteItem(final int position) {
recipeList.remove(position);
notifyDataSetChanged();
}

Updating Item in RecyclerView

I'm making a to do list app using a RecyclerView. When a task is clicked a dialog will appear and the user will be able to edit the name of the task. Once the user exists the dialog I want to reflect the changes of the task in the RecyclerView.
I have an activity called ListActivity that hosts a fragment which contains the RecyclerView. Likewise, I create my AlertDialog in a class called EditTaskFragment. Lastly, I store all the task objects in an arraylist in a Singleton class called TaskLab.
To retrieve the String after the user changes the name of a task item in the RecyclerView I am calling onActivityResult() in the ListFragment class. But I'm not sure how to update the task object that is stored in my Singleton and then how to get the ViewHolder to changes the Title field of a task item.
My ListFragment class
public class ListFragment extends Fragment {
private static final int REQUEST_TITLE = 0;
private RecyclerView mRecyclerView;
private TaskAdapter mAdapter;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_list, container, false);
mRecyclerView = view.findViewById(R.id.the_task_list);
mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
updateUI();
return view;
}
#Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if(resultCode == Activity.RESULT_OK && requestCode == ListFragment.REQUEST_TITLE) {
// Do something.
}
}
#Override
public void onResume() {
super.onResume();
updateUI();
}
public void updateUI() {
List<Task> taskList = TaskLab.get(getActivity()).getTaskList();
if(mAdapter == null) {
mAdapter = new TaskAdapter(taskList);
mRecyclerView.setAdapter(mAdapter);
}else {
mAdapter.notifyDataSetChanged();
}
}
private class TaskAdapter extends RecyclerView.Adapter<TaskHolder>{
private List<Task> mTaskList;
public TaskAdapter(List<Task> taskList) {
mTaskList = taskList;
}
#Override
public TaskHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(getActivity()).inflate(R.layout.task_list_layout, parent, false);
return new TaskHolder(view);
}
#Override
public void onBindViewHolder(TaskHolder holder, int position) {
Task currentTask = mTaskList.get(position);
holder.bindData(currentTask);
}
#Override
public int getItemCount() {
return mTaskList.size();
}
}
private class TaskHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
private Task mTask;
private TextView mTaskTitle;
private CheckBox mSolved;
private static final String DIALOG = "edit_dialog";
public TaskHolder(View itemView) {
super(itemView);
itemView.setOnClickListener(this);
mTaskTitle = itemView.findViewById(R.id.task_title);
mSolved = itemView.findViewById(R.id.task_solved);
}
public void bindData(Task task) {
mTask = task;
mTaskTitle.setText(mTask.getTitle());
mSolved.setChecked(mTask.isSolved());
}
#Override
public void onClick(View view) {
FragmentManager manager = getFragmentManager();
EditTaskFragment dialog = EditTaskFragment.newInstance(mTask.getTitle());
dialog.setTargetFragment(ListFragment.this, REQUEST_TITLE);
dialog.show(manager, DIALOG);
}
}
}
My EditTaskFragment class
public class EditTaskFragment extends DialogFragment {
private EditText mTaskTitle;
private String mTaskName;
private static final String ARG_TASK_TITLE = "task_title";
public static final String EXTRA_TASK_TITLE = "list_app_task_title";
private void sendResult(int resultCode, String taskName) {
if(getTargetFragment() == null) {
return;
}
Intent intent = new Intent();
intent.putExtra(EXTRA_TASK_TITLE,taskName);
getTargetFragment().onActivityResult(getTargetRequestCode(),resultCode, intent);
}
public static EditTaskFragment newInstance(String taskName) {
Bundle args = new Bundle();
args.putString(ARG_TASK_TITLE, taskName);
EditTaskFragment fragment = new EditTaskFragment();
fragment.setArguments(args);
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mTaskName = getArguments().getString(ARG_TASK_TITLE);
}
#Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
View view = LayoutInflater.from(getActivity()).inflate(R.layout.fragment_edit_task_dialog, null);
mTaskTitle = view.findViewById(R.id.edit_task_title);
mTaskTitle.setText(mTaskName);
return new AlertDialog.Builder(getActivity())
.setView(view)
.setTitle(R.string.edit_task_dialog_title)
.setPositiveButton(R.string.edit_task_dialog_positive, new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialogInterface, int i) {
sendResult(Activity.RESULT_OK, mTaskTitle.getText().toString());
}
})
.setNegativeButton(R.string.edit_task_dialog_negative, null)
.create();
}
}
My Singleton class - TaskLab
public class TaskLab {
private static TaskLab sTaskLab;
private List<Task> mTaskList;
private TaskLab(Context context){
mTaskList = new ArrayList<>();
for(int i = 0; i < 10; i++) {
Task task = new Task();
task.setTitle("Task #" + i);
task.setSolved(i%2 == 0);
mTaskList.add(task);
}
}
public static TaskLab get(Context context) {
if(sTaskLab == null) {
sTaskLab = new TaskLab(context);
}
return sTaskLab;
}
public List<Task> getTaskList(){
return mTaskList;
}
public Task getTask(int id){
for(Task task : mTaskList) {
if(task.getId().equals(id)){
return task;
}
}
return null;
}
}

In EditTaskFragment.sendResult() you are calling onActivityResult() of the target fragment. This is wrong. onActivityResult() is meant to be called by the framework, not the programmer.
What you have to do is use the enclosing activity of the fragments in order to pass data between the fragments.
Define an interface TaskChangedListener
Make your activity implement it, as well as ListFragment
In EditTaskFragment.sendResult(), use ((TaskChangedListener) getActivity()).onTaskChanged(taskName)
In onTaskChanged() of the activity, you will need to find the ListFragment (you can find it by tag from the fragment manager) and then call its onTaskChanged() from there.
In onTaskChanged() of ListFragment do:
List taskList = TaskLab.get(getActivity()).getTaskList();
mAdapter.clear();
mAdapter.addAll(taskList);
mAdapter.notifyDataSetChanged();
You will need to add the clear() and addAll() methods to your TaskAdapter class:
void clear() {
mTaskList.clear();
}
void addAll(List<Task> taskList) {
mTaskList.addAll(taskList);
}
As a next step

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);