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.

Adding click listener to two buttons in PagerAdpater CardViews

In my project, I have a PagerAdapter to inflate CardViews that hold text objects created by the user.
On each CardView I have edit and delete buttons to access methods to do with the ArrayList holding the text objects.
I have coded an interface in my adapter to handle clicks made within the text object creation activity. However, my instatiateItem method in my adapter is now showing on the #Override annotation "Method does not override method from its superclass". When I remove the #Override annotation I get an error in my Logcat:
java.lang.UnsupportedOperationException: Required method instantiateItem was not overridden
How do I implement a click listener for buttons on a CardView in a PagerAdapter?
Adapter code:
public class CreateAdapter extends PagerAdapter {
private List<PdfPage> pagesList;
private LayoutInflater layoutInflater;
private Context context;
private onItemClickListener mListener;
public interface onItemClickListener{
//click method for edit button
void onEditClick(int position);
//click method for delete button
void onDeleteClick(int position);
}
public void setOnItemClickListener(onItemClickListener listener){
mListener = listener;
}
public CreateAdapter(List<PdfPage> pagesList, Context context) {
this.pagesList = pagesList;
this.context = context;
}
#Override
public int getCount() {
return pagesList.size();
}
#Override
public boolean isViewFromObject(#NonNull View view, #NonNull Object object) {
return view.equals(object);
}
#NonNull
#Override
public Object instantiateItem(#NonNull ViewGroup container, final int position, final onItemClickListener listener) {
layoutInflater = LayoutInflater.from(context);
View view = null;
if(pagesList.get(position).getPageType() == "Text") {
view = layoutInflater.inflate(R.layout.create_text_cardview, container, false);
TextView inputText = view.findViewById(R.id.inputTextView);
ImageButton editButton = view.findViewById(R.id.imageButtonEdit);
ImageButton deleteButton = view.findViewById(R.id.imageButtonDelete);
//if this works, see 12:30 of video for image getter
inputText.setText(pagesList.get(position).getPageText());
//edit click listener
editButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (listener != null){
int position2 = pagesList.indexOf(pagesList.get(position));
listener.onEditClick(position2);
}
}
});
//delete click listener
deleteButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (listener != null){
int position3 = pagesList.indexOf(pagesList.get(position));
listener.onDeleteClick(position3);
}
}
});
container.addView(view, 0);
}
//put else statement here for image cardView
assert view != null;
return view;
}
#Override
public void destroyItem(#NonNull ViewGroup container, int position, #NonNull Object object) {
container.removeView((View)object);
}
Activity code:
public class CreateActivity extends AppCompatActivity {
ViewPager viewPager;
CreateAdapter createAdapter;
List<PdfPage> pdfPageList;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_create);
pdfPageList = new ArrayList<>();
createAdapter = new CreateAdapter(pdfPageList, this);
viewPager = findViewById(R.id.viewPager);
viewPager.setAdapter(createAdapter);
viewPager.setPadding(130, 0, 130, 0);
}
#Override
protected void onStart() {
super.onStart();
createAdapter = new CreateAdapter(pdfPageList, this);
viewPager = findViewById(R.id.viewPager);
viewPager.setAdapter(createAdapter);
viewPager.setPadding(130, 0, 130, 0);
createAdapter.setOnItemClickListener(new CreateAdapter.onItemClickListener() {
#Override
public void onEditClick(int position) {
}
#Override
public void onDeleteClick(int position) {
pdfPageList.remove(position);
}
});
}

Your instantiateItem method does not override from it's superclass because you added an extra argument final onItemClickListener listener.
As you are using the same clickListener for all entries and passing the item position as an argument, I suggest that you pass the onItemClickListener in the adapter constructor, or just set it via
public void setOnItemClickListener(onItemClickListener listener){
mListener = listener;
}
Adapter code:
public class CreateAdapter extends PagerAdapter {
private List<PdfPage> pagesList;
private LayoutInflater layoutInflater;
private Context context;
private onItemClickListener mListener;
public interface onItemClickListener{
//click method for edit button
void onEditClick(int position);
//click method for delete button
void onDeleteClick(int position);
}
public void setOnItemClickListener(onItemClickListener listener){
mListener = listener;
}
public CreateAdapter(List<PdfPage> pagesList, Context context) {
this.pagesList = pagesList;
this.context = context;
}
#Override
public int getCount() {
return pagesList.size();
}
#Override
public boolean isViewFromObject(#NonNull View view, #NonNull Object object) {
return view.equals(object);
}
#NonNull
#Override
public Object instantiateItem(#NonNull ViewGroup container, final int position) {
layoutInflater = LayoutInflater.from(context);
View view = null;
if(pagesList.get(position).getPageType() == "Text") {
view = layoutInflater.inflate(R.layout.create_text_cardview, container, false);
TextView inputText = view.findViewById(R.id.inputTextView);
ImageButton editButton = view.findViewById(R.id.imageButtonEdit);
ImageButton deleteButton = view.findViewById(R.id.imageButtonDelete);
//if this works, see 12:30 of video for image getter
inputText.setText(pagesList.get(position).getPageText());
//edit click listener
editButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (mlistener != null){
int position2 = pagesList.indexOf(pagesList.get(position));
mlistener.onEditClick(position2);
}
}
});
//delete click listener
deleteButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (mlistener != null){
int position3 = pagesList.indexOf(pagesList.get(position));
mlistener.onDeleteClick(position3);
}
}
});
container.addView(view, 0);
}
//put else statement here for image cardView
assert view != null;
return view;
}
#Override
public void destroyItem(#NonNull ViewGroup container, int position, #NonNull Object object) {
container.removeView((View)object);
}
And your Activity code could stay as it is.

Convert ListView to RecyclerView

i have a list view in my app.
I want to change it to an recycler view, but even with different tutorials i dont get it.
I was using this: https://www.spreys.com/listview-to-recyclerview/
I failed with the "getView" part here.
Here is my code of the ListActivity and LeagueArrayAdapter.
Thanks for your help.
ListActivity:
public class ListActivity extends AppCompatActivity implements AdapterView.OnItemClickListener {
private ArrayAdapter adapter;
private final int REQUEST_CODE_EDIT = 1;
private static LeagueDAO leagueDAO;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list);
leagueDAO = MainActivity.getLeagueDAO();
List<League> allLeagues1 = leagueDAO.getLeagues();
if (allLeagues1.size() == 0) {
leagueDAO.insert(new League("HVM Landesliga 19/20","https://hvmittelrhein-handball.liga.nu/cgi-bin/WebObjects/nuLigaHBDE.woa/wa/groupPage?championship=MR+19%2F20&group=247189"));
allLeagues1 = leagueDAO.getLeagues();
}
adapter = new LeagueArrayAdapter(this, R.layout.league, allLeagues1);
ListView lv = findViewById(R.id.league_list);
lv.setAdapter(adapter);
lv.setOnItemClickListener(this);
registerForContextMenu(lv);
Button btn_league_add = findViewById(R.id.btn_league_add);
btn_league_add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(ListActivity.this, EditActivity.class);
startActivity(intent);
}
});
}
#Override
public void onCreateContextMenu(ContextMenu contMenu, View v,
ContextMenu.ContextMenuInfo contextmenuInfo) {
super.onCreateContextMenu(contMenu, v, contextmenuInfo);
getMenuInflater().inflate(R.menu.team_list_context_menu, contMenu);
}
#Override
public boolean onContextItemSelected(MenuItem item) {
AdapterView.AdapterContextMenuInfo acmi=
(AdapterView.AdapterContextMenuInfo) item.getMenuInfo();
League league = (League)adapter.getItem(acmi.position);
switch (item.getItemId()) {
case R.id.evliconit_edit:
editEntry(league, acmi.position);
return true;
case R.id.evliconit_del:
leagueDAO.delete(league);
adapter.remove(league);
adapter.notifyDataSetChanged();
return true;
default:
return super.onContextItemSelected(item);
}
}
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
League team = (League)adapter.getItem(position);
editEntry(team, position);
}
private void editEntry(League league, int position) {
Intent intent = new Intent(this, EditActivity.class);
intent.putExtra("team", league);
intent.putExtra("position", position);
startActivityForResult(intent, REQUEST_CODE_EDIT);
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
super.onActivityResult(requestCode, resultCode, intent);
if (requestCode == REQUEST_CODE_EDIT && resultCode == RESULT_OK && intent != null) {
Bundle extras = intent.getExtras();
int position = extras.getInt("position");
League league = (League) adapter.getItem(position);
league.setLeague_name(extras.getString("league_name"));
league.setLeague_url(extras.getString("league_url"));
adapter.notifyDataSetChanged();
}
}
#Override
protected void onRestart() {
super.onRestart();
leagueDAO = MainActivity.getLeagueDAO();
List<League> allLeagues1 = leagueDAO.getLeagues();
adapter = new LeagueArrayAdapter(this, R.layout.league, allLeagues1);
ListView lv = findViewById(R.id.league_list);
lv.setAdapter(adapter);
lv.setOnItemClickListener(this);
registerForContextMenu(lv);
}
LeagueArrayAdapter:
public class LeagueArrayAdapter extends ArrayAdapter<League> {
private List<League> leagues;
private Context context;
private int layout;
public LeagueArrayAdapter(Context context, int layout, List<League> leagues) {
super(context, layout, leagues);
this.context = context;
this.layout = layout;
this.leagues = leagues;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
League league = leagues.get(position);
if (convertView == null)
convertView = LayoutInflater.from(context).inflate(layout, null);
TextView tv_name = convertView.findViewById(R.id.tv_name);
TextView tv_url = convertView.findViewById(R.id.tv_url);
tv_name.setText(league.getLeague_name());
tv_url.setText(league.getLeague_url());
return convertView;
}
}
Update: app crashed when opened the activity
public class ListActivity extends AppCompatActivity implements AdapterView.OnItemClickListener {
private ArrayAdapter adapter;
private final int REQUEST_CODE_EDIT = 1;
private static LeagueDAO leagueDAO;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list);
leagueDAO = MainActivity.getLeagueDAO();
List<League> allLeagues1 = leagueDAO.getLeagues();
if (allLeagues1.size() == 0) {
leagueDAO.insert(new League("HVM Landesliga 19/20","https://hvmittelrhein-handball.liga.nu/cgi-bin/WebObjects/nuLigaHBDE.woa/wa/groupPage?championship=MR+19%2F20&group=247189"));
allLeagues1 = leagueDAO.getLeagues();
}
// adapter = new LeagueArrayAdapter(this, R.layout.league, allLeagues1);
RecyclerView lv = findViewById(R.id.league_list);
lv.setHasFixedSize(true);
lv.setLayoutManager(new LinearLayoutManager(this));
lv.setAdapter(new LeagueArrayAdapter(allLeagues1));
// lv.setOnItemClickListener(this);
registerForContextMenu(lv);
Button btn_league_add = findViewById(R.id.btn_league_add);
btn_league_add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(ListActivity.this, EditActivity.class);
startActivity(intent);
}
});
}

I reconstructed your ListView Adapter using RecyclerView.Adapter.
onCreateView is called for every visible container on your screen. If your screen can show 10 rows of data RecyclerView makes 11 - 12 containers (ViewHolder)
onBindView updates those containers with new data when you scroll.
MyViewHolder is the object that holds data about every row of data (container)
static class and bind() function inside to avoid any memory leak in your adapter.
We have access to Context in RecyclerView.Adapter using itemView and parent
itemView is the inflated View for each container (ViewHolder).
Initialize your Views inside ViewHolder's constructor so they get assigned once.
public class LeagueArrayAdapter extends RecyclerView.Adapter<LeagueArrayAdapter.MyViewHolder> {
private ArrayList<League> leagues;
public LeagueArrayAdapter(ArrayList<League> leagues) {
this.leagues = leagues;
}
#NonNull
#Override
public MyViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
return LayoutInflater.from(parent.getContext()).inflate(R.layout.row_league, parent, false);
}
#Override
public void onBindViewHolder(#NonNull MyViewHolder holder, int position) {
holder.bind(leagues.get(position));
}
#Override
public int getItemCount() {
return 0;
}
static class MyViewHolder extends RecyclerView.ViewHolder {
TextView tv_name;
TextView tv_url;
public MyViewHolder(#NonNull View itemView) {
super(itemView);
tv_name = itemView.findViewById(R.id.tv_name);
tv_url = itemView.findViewById(R.id.tv_url);
}
void bind(League league) {
tv_name.setText(league.getLeague_name());
tv_url.setText(league.getLeague_url());
}
}
}
Your Activity:
LinearLayoutManager for a linear layout
GridLayoutManager for a grid layout
setHasFixedSize() enhances your RecyclerView's speed if you are sure the RecyclerView itself won't change width or height.
public class LeagueActivity extends AppCompatActivity {
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.YOUR_ACTIVITY_LAYOUT_ID);
...
RecyclerView recyclerView = findViewById(R.id.YOUR_RECYCLER_VIEW_ID);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setAdapter(new LeagueArrayAdapter(SEND_YOUR_ARRAY_OF_LEAGUE));
}
}

I suggest checking the Groupie Lbrary, it works with recyclerView and it makes life much easier for you, here is an example of how you can use it (I'm writing the code in kotlin but it shouldn't be that different from java)
first, add those lines to your Build.gradle (app) file
implementation 'com.xwray:groupie:2.3.0'
implementation 'com.xwray:groupie-kotlin-android-extensions:2.3.0'
then inside your activity create an adapter then set the adapter to your recyclerView
val myAdapter = GroupAdapter<ViewHolder>()
recyclerView.adapter = myAdapter
and just like this you set the adapter to your recyclerView, but you have to create "Items" to put inside the recyclerView. you can create an Item like so
class MyItem: Item() {
override fun getLayout() = R.layout.layout_seen
override fun bind(viewHolder: ViewHolder, position: Int){
}
}
in the getLayout method, you return the layout that you to display inside the recyclerView,
you can use the bind method to do any kind of modifications we want to apply to our layout that we are displaying.
lastly, we can add our items to the adapter this way
myAdapter.add(MyItem())
myAdapter.notifyDataSetChanged()
for more details check the library, in here I just explained how you can simply add an item to your RecyclerView

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