Is this a wrong way to implement a RecyclerView in Android?

Is this a wrong way to implement a RecyclerView in Android? - android

Im trying to implement a RecyclerView in my app. This is my Adapter class:
public class AdapterItemsList extends RecyclerView.Adapter<AdapterItemsList.ViewHolderItems>
{
private ArrayList<CItem> items;
public AdapterItemsList(ArrayList<CItem> items)
{
this.items = items;
}
#NonNull
#Override
public ViewHolderItems onCreateViewHolder(#NonNull ViewGroup parent, int viewType)
{
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.item_counter, null, false);
return new ViewHolderItems(view);
}
#Override
public void onBindViewHolder(#NonNull final ViewHolderItems holder, final int position)
{
holder.asignarDatos(items.get(holder.getAdapterPosition()));
holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
#Override
public boolean onLongClick(View view) {
//deleteSelectedItem() method gonna be here
Toast.makeText(view.getContext(), String.valueOf(holder.getAdapterPosition())
, Toast.LENGTH_SHORT).show();
return false;
}
});
holder.counterAdd.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Integer auxInteger = Integer.parseInt(holder.itemNumber.getText().toString());
auxInteger += 1;
holder.itemNumber.setText(auxInteger.toString());
items.get(holder.getAdapterPosition()).setObjectNumber(Integer.parseInt(holder.itemNumber.getText().toString()));
}
});
holder.counterSubtract.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Integer auxInteger = Integer.parseInt(holder.itemNumber.getText().toString());
if (auxInteger > 0)
{
auxInteger -= 1;
holder.itemNumber.setText(auxInteger.toString());
items.get(holder.getAdapterPosition()).setObjectNumber(Integer.parseInt(holder.itemNumber.getText().toString()));
}
}
});
}
#Override
public int getItemCount()
{
return items.size();
}
public class ViewHolderItems extends RecyclerView.ViewHolder
{
TextView itemName;
TextView itemNumber;
Button counterAdd;
Button counterSubtract;
public ViewHolderItems(View itemView)
{
super(itemView);
itemName = (TextView) itemView.findViewById(R.id.textViewItemCounterName);
itemNumber = (TextView) itemView.findViewById(R.id.textViewItemCounterNumber);
counterAdd = (Button) itemView.findViewById(R.id.buttonItemCounterAdd);
counterSubtract = (Button) itemView.findViewById(R.id.buttonItemCounterSubtract);
}
public void asignarDatos(CItem item)
{
itemName.setText(item.getObjectName());
itemNumber.setText(item.getObjectNumber().toString());
}
}
}
The code that "creates" the adapter:
private void CreateAdapter() {
recyclerViewItems.setAdapter(null);
items.clear();
//I dont post the code, but this just gets data from a SQLite database and populate "items".
LoadClientsList();
final AdapterItemsList adapter = new AdapterItemsList(items);
recyclerViewItems.setAdapter(adapter);
}
As you can see, I never use "implements View.OnLongClickListener" or something like that, but I just set the OnClickListener inside onBindViewHolder. Now there is a "Toast" inside (which appears just fine when I test the app), but later on, there should be my "delete item" dialog, that gonna give the user the change to Accept or Cancel (an usual dialog). If the user press "accept" then I gonna remove the item from the list.
I gonna admit, Im not an Android or Java Ninja, so I know there are horrendous mistakes probably. But the thing is, the app is working by now (the Toast appears correctlywhen I long-press an item), but the fact that I never use "implements", while I see everyone does it in StackOverflow questions related to RecyclerViews and Adapters, make me think Im making (several) serious mistakes.
I could admit since Im not a master at Java fundamentals (some years working with COBOL already that I remember almost NULL of OOP), I don't see where my mistakes are, but still, any help will be much appreciated.
Thanks in regard!
UPDATE:
Ok I was changing my code and now its like follows:
public class AdapterItemsList extends
RecyclerView.Adapter<AdapterItemsList.ViewHolderItems> implements
View.OnClickListener {
private ArrayList<CItem> items;
/* Added this */
private View.OnClickListener listener;
public AdapterItemsList(ArrayList<CItem> items)
{
this.items = items;
}
#NonNull
#Override
public ViewHolderItems onCreateViewHolder(#NonNull ViewGroup parent, int viewType)
{
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.item_counter, null, false);
/* Added this */
view.setOnClickListener(this);
return new ViewHolderItems(view);
}
#Override
public void onBindViewHolder(#NonNull final ViewHolderItems holder, final int position)
{
holder.asignarDatos(items.get(holder.getAdapterPosition()));
holder.counterAdd.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Integer auxInteger = Integer.parseInt(holder.itemNumber.getText().toString());
auxInteger += 1;
holder.itemNumber.setText(auxInteger.toString());
items.get(holder.getAdapterPosition()).setObjectNumber(Integer.parseInt(holder.itemNumber.getText().toString()));
}
});
holder.counterSubtract.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Integer auxInteger = Integer.parseInt(holder.itemNumber.getText().toString());
if (auxInteger > 0)
{
auxInteger -= 1;
holder.itemNumber.setText(auxInteger.toString());
items.get(holder.getAdapterPosition()).setObjectNumber(Integer.parseInt(holder.itemNumber.getText().toString()));
}
}
});
}
#Override
public int getItemCount() { [...] }
/* Added this */
public void setOnClickListener(View.OnClickListener listener)
{
this.listener = listener;
}
/* Added this */
#Override
public void onClick(View view) {
if (listener != null)
{
listener.onClick(view);
}
}
public class ViewHolderItems extends RecyclerView.ViewHolder { [...] } }
Code where I create the adapter:
private void CreateAdapter() {
recyclerViewItems.setAdapter(null);
items.clear();
LoadClientsList();
final AdapterItemsList adapter = new AdapterItemsList(items);
/* Added this */
adapter.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Toast.makeText(getApplicationContext(), String.valueOf(recyclerViewItems.getChildAdapterPosition(view)), Toast.LENGTH_SHORT).show();
}
});
recyclerViewItems.setAdapter(adapter);
}
The "recyclerViewItems.getChildAdapterPosition(view)" finally solves my problem (didn't mentioned before, but it was the reason why I put the "setOnClick..." inside the onBindViewHolder method, just because I needed the position of the pressed item and I couldnt figure out how on earth to access it).
So now I set the listener when I create the adapter instead of when Binding the View holder, which I guess it's better.
Still, I didnt change the "holder.counterAdd.setOnClickListener" and "holder.counterSubtract.setOnClickListener" lines, since I think they must be inside the onBindViewHolder method, but I guess Im still wrong on that.

I disagree with most of the comments on your question, and I think that the way you've written your adapter is pretty good. It's not perfect, but there is nothing wrong with manually setting a View.OnClickListener to some (or many) views inside your ViewHolder. In fact, this is the Google-recommended way of doing things!
I would make some changes, however. The first would be to move the declaration of your click listeners into the onCreateViewHolder() method (by putting them inside the ViewHolder's constructor). The second would be to add checks for NO_POSITION to make sure you handle the case where an item has been removed from your adapter but the layout hasn't been recalculated yet.
Here is what I'd recommend:
public ViewHolderItems(View itemView)
{
super(itemView);
itemName = (TextView) itemView.findViewById(R.id.textViewItemCounterName);
itemNumber = (TextView) itemView.findViewById(R.id.textViewItemCounterNumber);
counterAdd = (Button) itemView.findViewById(R.id.buttonItemCounterAdd);
counterSubtract = (Button) itemView.findViewById(R.id.buttonItemCounterSubtract);
itemView.setOnLongClickListener(new View.OnLongClickListener() {
#Override
public boolean onLongClick(View view) {
deleteItem();
return true;
}
});
counterAdd.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
itemAdd();
}
});
counterSubtract.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
itemSubtract();
}
});
}
private void deleteItem() {
int position = getAdapterPosition();
if (position != RecyclerView.NO_POSITION) {
items.remove(position);
adapter.notifyItemRemoved(position);
}
}
private void itemAdd() {
int position = getAdapterPosition();
if (position != RecyclerView.NO_POSITION) {
CItem item = items.get(position);
item.setObjectNumber(item.getObjectNumber() + 1);
adapter.notifyItemChanged(position);
}
}
private void itemSubtract() {
int position = getAdapterPosition();
if (position != RecyclerView.NO_POSITION) {
CItem item = items.get(position);
if (item.getObjectNumber() > 0) {
item.setObjectNumber(item.getObjectNumber() - 1);
adapter.notifyItemChanged(position);
}
}
}
And then your onBindViewHolder() is extremely simple:
#Override
public void onBindViewHolder(#NonNull ViewHolderItems holder, int position)
{
holder.asignarDatos(items.get(position));
}
So, let's talk about what I'm doing here.
First, I pushed all of the listener setup into the constructor of your ViewHolder. This means that the listeners are all assigned exactly once. In order to make that still function in a world where ViewHolders are recycled and attached to different items, we have to use getAdapterPosition() to make sure that we're always interacting with the correct item in your list.
We have to check for NO_POSITION because RecyclerView layout operations are asynchronous: when you delete an item from the list, there is a gap where the item doesn't exist in your adapter any more but still is displayed on screen. In this gap, the user might tap a button! In these cases, we just ignore the user input.
I also changed how you update the values of your items, and how you display those updates. Rather than getting the text and parsing it and then re-setting it, I always go through the adapter. Remember that the goal of your RecyclerView implementation is to be able to display any element in your list correctly. The best way to do this is to update the element in your data set, and then notify the RecyclerView that that element has changed, and let onBindViewHolder() take care of the required updates.

Related

Having challenge in RecyclerView item's onClickListener

I have an item list which are placed under a RecyclerView. On any item, there a quantity(add or subtract). When add is selected, the quantity should increase one.
But when i clicked on '+' for the first time, the value of quantity is setting to 1 and soon after resetting to 0, but when i click on second time the value is becoming '1'. Similarly when i click on next time the value is setting to 2 and after a fraction of second it is still getting to 1 and i click on another time the value is becoming 2. Why by first click is not getting recognized? Can someone please help me here?
public class ItemListAdapter extends RecyclerView.Adapter<ItemListAdapter.ItemViewHolder>{
private Context mContext;
private List<Items> itemsList;
private OnItemListListner onClick;
public ItemListAdapter(Context mContext,List<Items> itemsList)
{
this.mContext=mContext;
this.itemsList=itemsList;
}
#NonNull
#Override
public ItemViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
LayoutInflater inflater=LayoutInflater.from(mContext);
View view=inflater.inflate(R.layout.item_details_layout,null);
return new ItemListAdapter.ItemViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull final ItemViewHolder holder, final int position) {
Items items=itemsList.get(position);
Log.d("onBindViewHolder",items.getItemName());
holder.itemNameTV.setText(items.getItemName());
String strItemPrice=mContext.getResources().getString(R.string.Rs)+" "+String.valueOf(items.getItemPrice());
holder.itemPriceTV.setText(strItemPrice);
holder.itemDescTV.setText(items.getItemDescription());
Glide.with(mContext).load(items.getItemImagePath()).into(holder.imageView);
holder.itemAdd.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
int intCurrentQuantity=Integer.valueOf(holder.itemQuantity.getText().toString());
intCurrentQuantity+=1;
Log.d("myQuantity",String.valueOf(intCurrentQuantity));
holder.itemQuantity.setText(String.valueOf(intCurrentQuantity));
notifyItemChanged(holder.getAdapterPosition());
}
});
holder.itemNameTV.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
onClick.onItemListClick(position);
}
});
holder.itemPriceTV.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
onClick.onItemListClick(position);
}
});
holder.itemDescTV.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
onClick.onItemListClick(position);
}
});
holder.imageView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
onClick.onItemListClick(position);
}
});
}
#Override
public int getItemCount() {
return itemsList.size();
}
public void SetOnClick(OnItemListListner onClick)
{
this.onClick=onClick;
}
class ItemViewHolder extends RecyclerView.ViewHolder {
ImageView imageView;
TextView itemNameTV,itemPriceTV,itemDescTV,itemQuantity,itemSubtract,itemAdd;
public ItemViewHolder(#NonNull View itemView) {
super(itemView);
imageView=itemView.findViewById(R.id.itemImageView);
itemNameTV=itemView.findViewById(R.id.itemNameTextView);
itemPriceTV=itemView.findViewById(R.id.itemPriceTextView);
itemDescTV=itemView.findViewById(R.id.itemDescritionTextView);
itemQuantity=itemView.findViewById(R.id.itemQuantity);
itemSubtract=itemView.findViewById(R.id.subtractQuantity);
itemAdd=itemView.findViewById(R.id.addQuantity);
}
}
public interface OnItemListListner{
void onItemListClick(int position);
}
}

you should have the quantity property in Item model class and have to follow the code I added below.
holder.itemAdd.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
int quantity = item[getAdapterPosition()].quantity;
quantity = quantity +1;
item[getAdapterPosition()].setQuantity(quantity);
notifyItemChanged(getAdapterPosition());
}
});
Thanks.I am sure this will work for you.

Reviewd your code and then after i'm just agreed with Harsh's Answer
there is a two way to set your adapter. most commonly used Model for storing and retriving data.
You need to create a one model class and and set data first into the model then after get data from model and set into your adapter / notify your adapter.
You need to create one variable in model class like below snippet:
public class Item {
String mQty = "";
public String getmQty() {
return mQty;
}
public void setmQty(String mQty) {
this.mQty = mQty;
}
}
Helpful Answer: Click Me

Recycler view recycles the views on scroll and resets its content, so you have to persist the quantity qty variable. You can do it by two ways
Store quantity inside your Items model.
Persist quantity in seperate HashMap as item.getId() as key and qty as value.
then get and set from the model object or hashmap.

Check updated code
holder.itemAdd.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
int intCurrentQuantity=Integer.valueOf(holder.itemQuantity.getText().toString());
++intCurrentQuantity; //use this
Log.d("myQuantity",String.valueOf(intCurrentQuantity));
holder.itemQuantity.setText(String.valueOf(intCurrentQuantity));
notifyItemChanged(holder.getAdapterPosition());
}
});

How to make single selection in recyclerview [duplicate]

I know there are no default selection methods in the RecyclerView class, but I have tried in the following way:
public void onBindViewHolder(ViewHolder holder, final int position) {
holder.mTextView.setText(fonts.get(position).getName());
holder.checkBox.setChecked(fonts.get(position).isSelected());
holder.checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if(isChecked) {
for (int i = 0; i < fonts.size(); i++) {
fonts.get(i).setSelected(false);
}
fonts.get(position).setSelected(isChecked);
}
}
});
}
While trying this code, I got the expected output, but not completely.
I will explain this with images.
By default, the first item is selected from my adapter.
Then I select the 2nd, then the 3rd, then the 4th and finally the 5th one.
Here only the 5th should be selected, but all five are getting selected.
If I scroll the list to the bottom and come again to the top, I get what I expect.
How can I overcome this issue? And sometimes if I scroll the list very fast, some other item gets selected. How can I overcome this problem too?
While I was trying to use notifyDataSetChanged() after fonts.get(position).setSelected(isChecked);, I got the following exception:
java.lang.IllegalStateException: Cannot call this method while RecyclerView is computing a layout or scrolling
at android.support.v7.widget.RecyclerView.assertNotInLayoutOrScroll(RecyclerView.java:1462)
at android.support.v7.widget.RecyclerView$RecyclerViewDataObserver.onChanged(RecyclerView.java:2982)
at android.support.v7.widget.RecyclerView$AdapterDataObservable.notifyChanged(RecyclerView.java:7493)
at android.support.v7.widget.RecyclerView$Adapter.notifyDataSetChanged(RecyclerView.java:4338)
at com.app.myapp.screens.RecycleAdapter.onRowSelect(RecycleAdapter.java:111)

The solution for the issue:
public class yourRecyclerViewAdapter extends RecyclerView.Adapter<yourRecyclerViewAdapter.yourViewHolder> {
private static CheckBox lastChecked = null;
private static int lastCheckedPos = 0;
public void onBindViewHolder(ViewHolder holder, final int position) {
holder.mTextView.setText(fonts.get(position).getName());
holder.checkBox.setChecked(fonts.get(position).isSelected());
holder.checkBox.setTag(new Integer(position));
//for default check in first item
if(position == 0 && fonts.get(0).isSelected() && holder.checkBox.isChecked())
{
lastChecked = holder.checkBox;
lastCheckedPos = 0;
}
holder.checkBox.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View v)
{
CheckBox cb = (CheckBox)v;
int clickedPos = ((Integer)cb.getTag()).intValue();
if(cb.isChecked())
{
if(lastChecked != null)
{
lastChecked.setChecked(false);
fonts.get(lastCheckedPos).setSelected(false);
}
lastChecked = cb;
lastCheckedPos = clickedPos;
}
else
lastChecked = null;
fonts.get(clickedPos).setSelected(cb.isChecked);
}
});
}
}

It's quite late, but I'm still posting it as it may help someone else.
Use the code below as a reference to check a single item in RecyclerView:
/**
* Created by subrahmanyam on 28-01-2016, 04:02 PM.
*/
public class SampleAdapter extends RecyclerView.Adapter<SampleAdapter.ViewHolder> {
private final String[] list;
private int lastCheckedPosition = -1;
public SampleAdapter(String[] list) {
this.list = list;
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = View.inflate(parent.getContext(), R.layout.sample_layout, null);
ViewHolder holder = new ViewHolder(view);
return holder;
}
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
holder.choiceName.setText(list[position]);
holder.radioButton.setChecked(position == lastCheckedPosition);
}
#Override
public int getItemCount() {
return list.length;
}
public class ViewHolder extends RecyclerView.ViewHolder {
#Bind(R.id.choice_name)
TextView choiceName;
#Bind(R.id.choice_select)
RadioButton radioButton;
public ViewHolder(View itemView) {
super(itemView);
ButterKnife.bind(this, itemView);
radioButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
int copyOfLastCheckedPosition = lastCheckedPosition;
lastCheckedPosition = getAdapterPosition();
notifyItemChanged(copyOfLastCheckedPosition);
notifyItemChanged(lastCheckedPosition);
}
});
}
}
}

This is how it looks:
Inside your Adapter:
private int selectedPosition = -1;
And onBindViewHolder
#Override
public void onBindViewHolder(#NonNull MyViewHolder holder, int position) {
if (selectedPosition == position) {
holder.itemView.setSelected(true); //using selector drawable
holder.tvText.setTextColor(ContextCompat.getColor(holder.tvText.getContext(),R.color.white));
} else {
holder.itemView.setSelected(false);
holder.tvText.setTextColor(ContextCompat.getColor(holder.tvText.getContext(),R.color.black));
}
holder.itemView.setOnClickListener(v -> {
if (selectedPosition >= 0)
notifyItemChanged(selectedPosition);
selectedPosition = holder.getAdapterPosition();
notifyItemChanged(selectedPosition);
});
}
that’s it!
As you can see, I am just notifying (updating) the previous selected item and newly selected item.
My Drawable set it as a background for recyclerview child views:
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_focused="false" android:state_selected="true">
<shape android:shape="rectangle">
<solid android:color="#color/blue" />
</shape>
</item>

You need to clear the OnCheckedChangeListener before setting setChecked():
#Override
public void onBindViewHolder(final ViewHolder holder, int position) {
holder.mRadioButton.setOnCheckedChangeListener(null);
holder.mRadioButton.setChecked(position == mCheckedPosition);
holder.mRadioButton.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
mCheckedPosition = position;
notifyDataSetChanged();
}
});
}
This way it won't trigger the java.lang.IllegalStateException: Cannot call this method while RecyclerView is computing a layout or scrolling error.

Default value:
private int mCheckedPostion = -1;
Just use mCheckedPosition to save the status:
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
holder.checkBox.setChecked(position == mCheckedPostion);
holder.checkBox.setOnClickListener(v -> {
if (position == mCheckedPostion) {
holder.checkBox.setChecked(false);
mCheckedPostion = -1;
}
else {
mCheckedPostion = position;
notifyDataSetChanged();
}
});
}

It looks like there are two things at play here:
(1) The views are reused, so the old listener is still present.
(2) You are changing the data without notifying the adapter of the change.
I will address each separately.
(1) View reuse
Basically, in onBindViewHolder you are given an already initialized ViewHolder, which already contains a view. That ViewHolder may or may not have been previously bound to some data!
Note this bit of code right here:
holder.checkBox.setChecked(fonts.get(position).isSelected());
If the holder has been previously bound, then the checkbox already has a listener for when the checked state changes! That listener is being triggered at this point, which is what was causing your IllegalStateException.
An easy solution would be to remove the listener before calling setChecked. An elegant solution would require more knowledge of your views - I encourage you to look for a nicer way of handling this.
(2) Notify the adapter when data changes
The listener in your code is changing the state of the data without notifying the adapter of any subsequent changes. I don't know how your views are working so this may or may not be an issue. Typically when the state of your data changes, you need to let the adapter know about it.
RecyclerView.Adapter has many options to choose from, including notifyItemChanged, which tells it that a particular item has changed state. This might be good for your use:
if(isChecked) {
for (int i = 0; i < fonts.size(); i++) {
if (i == position) continue;
Font f = fonts.get(i);
if (f.isSelected()) {
f.setSelected(false);
notifyItemChanged(i); // Tell the adapter this item is updated
}
}
fonts.get(position).setSelected(isChecked);
notifyItemChanged(position);
}

This might help for those who want a single radiobutton to work -->
Radio Button RecycleView - Gist
If lambda expressions aren't supported, use this instead:
View.OnClickListener listener = new View.OnClickListener() {
#Override
public void onClick(View v) {
notifyItemChanged(mSelectedItem); // to update last selected item.
mSelectedItem = getAdapterPosition();
}
};

This happens because RecyclerView, as the name suggests, does a good job at recycling its ViewHolders. This means that every ViewHolder, when it goes out of sight (actually, it takes a little more than going out of sight, but it makes sense to simplify it that way), it is recycled; this implies that the RecyclerView takes this ViewHolder that is already inflated and replaces its elements with the elements of another item in your data set.
Now, what is going on here is that once you scroll down and your first, selected, ViewHolders go out of sight, they are being recycled and used for other positions of your data set. Once you go up again, the ViewHolders that were bound to the first 5 items are not necessarely the same, now.
This is why you should keep an internal variable in your adapter that remembers the selection state of each item. This way, in the onBindViewHolder method, you can know if the item whose ViewHolder is currently being bound was selected or not, and modify a View accordingly, in this case your RadioButton's state (though I would suggest to use a CheckBox if you plan on selecting multiple items).
If you want to learn more about RecyclerView and its inner workings, I invite you to check FancyAdapters, a project I started on GitHub. It is a collection of adapters that implement selection, drag&drop of elements and swipe to dismiss capabilities. Maybe by checking the code you can obtain a good understanding on how RecyclerView works.

This simple one worked for me
private RadioButton lastCheckedRB = null;
...
#Override
public void onBindViewHolder(final CoachListViewHolder holder, final int position) {
holder.priceRadioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
RadioButton checked_rb = (RadioButton) group.findViewById(checkedId);
if (lastCheckedRB != null && lastCheckedRB != checked_rb) {
lastCheckedRB.setChecked(false);
}
//store the clicked radiobutton
lastCheckedRB = checked_rb;
}
});

The following might be helpful for RecyclerView with Single Choice.
Three steps to do that,
1) Declare a global integer variable,
private int mSelectedItem = -1;
2) in onBindViewHolder
mRadio.setChecked(position == mSelectedItem);
3) in onClickListener
mSelectedItem = getAdapterPosition();
notifyItemRangeChanged(0, mSingleCheckList.size());
mAdapter.onItemHolderClick(SingleCheckViewHolder.this);

public class GetStudentAdapter extends
RecyclerView.Adapter<GetStudentAdapter.MyViewHolder> {
private List<GetStudentModel> getStudentList;
Context context;
RecyclerView recyclerView;
public class MyViewHolder extends RecyclerView.ViewHolder {
TextView textStudentName;
RadioButton rbSelect;
public MyViewHolder(View view) {
super(view);
textStudentName = (TextView) view.findViewById(R.id.textStudentName);
rbSelect = (RadioButton) view.findViewById(R.id.rbSelect);
}
}
public GetStudentAdapter(Context context, RecyclerView recyclerView, List<GetStudentModel> getStudentList) {
this.getStudentList = getStudentList;
this.recyclerView = recyclerView;
this.context = context;
}
#Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext())
.inflate(R.layout.select_student_list_item, parent, false);
return new MyViewHolder(itemView);
}
#Override
public void onBindViewHolder(final MyViewHolder holder, final int position) {
holder.textStudentName.setText(getStudentList.get(position).getName());
holder.rbSelect.setChecked(getStudentList.get(position).isSelected());
holder.rbSelect.setTag(position); // This line is important.
holder.rbSelect.setOnClickListener(onStateChangedListener(holder.rbSelect, position));
}
#Override
public int getItemCount() {
return getStudentList.size();
}
private View.OnClickListener onStateChangedListener(final RadioButton checkBox, final int position) {
return new View.OnClickListener() {
#Override
public void onClick(View v) {
if (checkBox.isChecked()) {
for (int i = 0; i < getStudentList.size(); i++) {
getStudentList.get(i).setSelected(false);
}
getStudentList.get(position).setSelected(checkBox.isChecked());
notifyDataSetChanged();
} else {
}
}
};
}
}

This is how the Adapter class looks like :
public class MyRecyclerViewAdapter extends RecyclerView.Adapter<MyRecyclerViewHolder>{
Context context;
ArrayList<RouteDetailsFromFirestore> routeDetailsFromFirestoreArrayList_;
public int lastSelectedPosition=-1;
public MyRecyclerViewAdapter(Context context, ArrayList<RouteDetailsFromFirestore> routeDetailsFromFirestoreArrayList)
{
this.context = context;
this.routeDetailsFromFirestoreArrayList_ = routeDetailsFromFirestoreArrayList;
}
#NonNull
#Override
public MyRecyclerViewHolder onCreateViewHolder(#NonNull ViewGroup viewGroup, int i)
{
// LayoutInflater layoutInflater = LayoutInflater.from(mainActivity_.getBaseContext());
LayoutInflater layoutInflater = LayoutInflater.from(viewGroup.getContext());
View view = layoutInflater.inflate(R.layout.route_details, viewGroup, false);
return new MyRecyclerViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull final MyRecyclerViewHolder myRecyclerViewHolder, final int i) {
/* This is the part where the appropriate checking and unchecking of radio button happens appropriately */
myRecyclerViewHolder.mRadioButton.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
if(b) {
if (lastSelectedPosition != -1) {
/* Getting the reference to the previously checked radio button and then unchecking it.lastSelectedPosition has the index of the previously selected radioButton */
//RadioButton rb = (RadioButton) ((MainActivity) context).linearLayoutManager.getChildAt(lastSelectedPosition).findViewById(R.id.rbRadioButton);
RadioButton rb = (RadioButton) ((MainActivity) myRecyclerViewHolder.mRadioButton.getContext()).linearLayoutManager.getChildAt(lastSelectedPosition).findViewById(R.id.rbRadioButton);
rb.setChecked(false);
}
lastSelectedPosition = i;
/* Checking the currently selected radio button */
myRecyclerViewHolder.mRadioButton.setChecked(true);
}
}
});
}
#Override
public int getItemCount() {
return routeDetailsFromFirestoreArrayList_.size();
}
} // End of Adapter Class
Inside MainActivity.java we call the ctor of Adapter class like this. The context passed is of MainActivity to the Adapter ctor :
myRecyclerViewAdapter = new MyRecyclerViewAdapter(MainActivity.this, routeDetailsList);

I got a solution that will save your selection when you open a recycler list.
var mSelectedItem = -1
// store saved selection
fun setSelection(position: Int) {
mSelectedItem = position
}
override fun onBindViewHolder(holder: GroupHolder, position: Int) {
holder.bind(dataList[position])
holder.radioButton.isChecked = position == mSelectedItem
}
inner class GroupHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
val radioButton: RadioButton = itemView.rbValue
fun bind(data: Data) = with(itemView) {
radioButton.text = data.name
val clickListener = View.OnClickListener {
mSelectedItem = bindingAdapterPosition
notifyDataSetChanged()
setSelection(mSelectedItem)
}
radioButton.setOnClickListener(clickListener)
}
}

After spending so many days over this, this is what I came up with which worked for me, and is good practice as well,
Create an interface, name it some listener: SomeSelectedListener.
Add a method which takes an integer:void onSelect(int position);
Initialise the listener in the recycler adapter's constructor as: a) first declare globally as: private SomeSelectedListener listener b) then in constructor initialise as: this.listener = listener;
Inside onClick() of checkbox inside onBindViewHolder(): update the method of the interface/listener by passing the position as: listener.onSelect(position)
In the model, add a variable for deselect say, mSelectedConstant and initialise it there to 0. This represents the default state when nothing is selected.
Add getter and setter for the mSelectedConstant in the same model.
Now, go to your fragment/activity and implement the listener interface. Then override its method: onSelect(int position). Within this method, iterate through your list which you are passing to your adapter using a for loop and setSelectedConstant to 0 for all:
Code
#Override
public void onTicketSelect(int position) {
for (ListType listName : list) {
listName.setmSelectedConstant(0);
}
Outside this, make the selected position constant 1:
Code
list.get(position).setmSelectedConstant(1);
Notify this change by calling: adapter.notifyDataSetChanged(); immediately after this.
Last step: go back to your adapter and update inside onBindViewHolder() after onClick() add the code to update the checkbox state,
Code
if (listVarInAdapter.get(position).getmSelectedConstant() == 1) {
holder.checkIcon.setChecked(true);
selectedTicketType = dataSetList.get(position);}
else {
commonHolder.checkCircularIcon.setChecked(false);
}

Here is a similar thing I have achieved.
The below code is from the application to select an address from a list of addresses that are displayed in cardview(cvAddress), so that on click of particular item(cardview) the imageView inside the item should set to a different resource (select/unselect):
#Override
public void onBindViewHolder(final AddressHolder holder, final int position)
{
holderList.add(holder);
holder.tvAddress.setText(addresses.get(position).getAddress());
holder.cvAddress.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
selectCurrItem(position);
}
});
}
private void selectCurrItem(int position)
{
int size = holderList.size();
for(int i = 0; i<size; i++)
{
if(i==position)
holderList.get(i).ivSelect.setImageResource(R.drawable.select);
else
holderList.get(i).ivSelect.setImageResource(R.drawable.unselect);
}
}
I don't know if this is the best solution or not, but this worked for me.

Please try this...
This works for me...
In the adapter, take a sparse Boolean array.
SparseBooleanArray sparseBooleanArray;
In the constructor, initialise this,
sparseBooleanArray = new SparseBooleanArray();
In the bind holder, add:
#Override
public void onBindViewHolder(DispositionViewHolder holder, final int position) {
holder.tv_disposition.setText(dispList.get(position).getName());
if(sparseBooleanArray.get(position,false))
{
holder.rd_disp.setChecked(true);
}
else
{
holder.rd_disp.setChecked(false);
}
setClickListner(holder,position);
}
private void setClickListner(final DispositionViewHolder holder, final int position) {
holder.rd_disp.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
sparseBooleanArray.clear();
sparseBooleanArray.put(position, true);
notifyDataSetChanged();
}
});
}
rd_disp is a radio button in the XML file.
So when the recycler view loads the items, in the bindView Holder, it checks whether the sparseBooleanArray contains the value "true", corresponding to its position.
If the value returned is true then we set the radio button selection true. Else we set the selection false.
In onclickHolder I have cleared the sparseArray and set the value to true corresponding to that position.
When I call notify datasetChange, it again calls the onBindViewHolder and the conditions are checked again. This makes our selection to only select a particular radio.

public class LastTransactionAdapter extends RecyclerView.Adapter<LastTransactionAdapter.MyViewHolder> {
private Context context;
private List<PPCTransaction> ppcTransactionList;
private static int checkedPosition = -1;
public LastTransactionAdapter(Context context, List<PPCTransaction> ppcTransactionList) {
this.context = context;
this.ppcTransactionList = ppcTransactionList;
}
#NonNull
#Override
public LastTransactionAdapter.MyViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
return new MyViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.last_transaction_item, parent, false));
}
#Override
public void onBindViewHolder(#NonNull LastTransactionAdapter.MyViewHolder holder, int position) {
holder.setLastTransaction(ppcTransactionList.get(position), position);
}
#Override
public int getItemCount() {
return ppcTransactionList.size();
}
public class MyViewHolder extends RecyclerView.ViewHolder {
private LinearLayout linTransactionItem;
private RadioButton radioButton;
private TextView tvDate, tvMerchantName, tvAmount, tvStatus;
public MyViewHolder(#NonNull View itemView) {
super(itemView);
linTransactionItem = itemView.findViewById(R.id.linTransactionItem);
tvDate = itemView.findViewById(R.id.tvDate);
tvMerchantName = itemView.findViewById(R.id.tvMerchantName);
tvAmount = itemView.findViewById(R.id.tvAmount);
tvStatus = itemView.findViewById(R.id.tvStatus);
radioButton = itemView.findViewById(R.id.radioButton);
}
public void setLastTransaction(PPCTransaction ppcTransaction, int position) {
tvDate.setText(ppcTransaction.getmDate());
tvMerchantName.setText(ppcTransaction.getmMerchantName());
tvAmount.setText(ppcTransaction.getmAmount());
tvStatus.setText(ppcTransaction.getmStatus());
if (checkedPosition == -1) {
radioButton.setChecked(false);
} else {
if (checkedPosition == getAdapterPosition()) {
radioButton.setChecked(true);
} else {
radioButton.setChecked(false);
}
}
linTransactionItem.setOnClickListener(v -> {
radioButton.setChecked(true);
if (checkedPosition != getAdapterPosition()) {
notifyItemChanged(checkedPosition);
checkedPosition = getAdapterPosition();
}
});
}
}

// This work for my with out any visual isue
data class buttonData(val button:RadioButton, val position: Int)
var selectedPosition = -1
override fun onBindViewHolder(holder: SingleChoiceAdapter.OptionHolder, position: Int) {
holder.viewDataBinding.option= options[position]
holder.viewDataBinding.radioButton.setChecked(position == selectedPosition);
buttonList.add( buttonData(holder.viewDataBinding.radioButton,position))
holder.viewDataBinding.radioButton.setOnClickListener {
selectedPosition= position
for(buttonData in buttonList ){
buttonData.button.isChecked = buttonData.position == position
}
}
}

Don't make it too complicated:
SharedPreferences sharedPreferences = getSharedPreferences("appdetails", MODE_PRIVATE);
String selection = sharedPreferences.getString("selection", null);
public void onBindViewHolder(ViewHolder holder, final int position) {
String name = fonts.get(position).getName();
holder.mTextView.setText(name);
if(selection.equals(name)) {
holder.checkBox.setChecked(false); //
holder.checkBox.setChecked(true);
}
holder.checkbox.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
SharedPreferences sharedPreferences = getSharedPreferences("appdetails", MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putString("selection", name);
r.setChecked(false);
editor.apply();
holder.checkBox.setChecked(true);
}
});
}

How to add/remove child items in a RecyclerView, suggestions for an Order Restaurant App?

Actually i'm trying to make an app that will permise to take orders in a restoraunt.
As probably you know when a waiter take's an order he can add any item from a menu to record's (something like a notebook) and even additionally he can add a variant to added item.
Example, i have a pizza menu in my app when i press some items from my menu it's added to the notebook (Menu and Notebook are 2 RecyclerView) after i've added the type of pizza's i can "modify" them by adding a subitem or better a child to the main item.
Or better i have 3 different pizza's on my notebook by clicking on one of them i'll be able to add a variant chosen from another recyclerView as "PIZZA" and variant "WITH PEPERONI" or "WITHOUT PEPERONI" or "WITH MORE MOZZARELLA".
For now i think i'm doing fine with the app like i have yet all what i need, as you can see on this GIF i'm adding from recyclerView "FOOD" to the "NOTEBOOK" recyclerView some items and by pressing VARIANTI i'm able to add Child items to last added FOOD.
But the issue comes when i have to delete a single VARIANT added to a food i would have some suggestion on how can i like click on a single VARIANT and would be able to delete the single one.
Here is my Adapter code:
public class AdapterPTERM extends RecyclerView.Adapter<AdapterPTERM.ExampleViewHolder> {
private List<ItemPTERM> mExampleList;
private final LayoutInflater mInflater;
private OnItemClickListener mListener;
private List<Variant> variants;
private ManageAddRemoveCallbacks mManageAddRemoveCallbacks ;
private View.OnClickListener varientClickListener = new View.OnClickListener() {
#Override
public void onClick(View v) {
if(v.getTag()!= null){
int position = (int) v.getTag();
}
}
};
public interface OnItemClickListener{
void onItemClick(int position);
}
public void setOnItemClickListener(OnItemClickListener listener){
mListener = listener;
}
#NonNull
#Override
public ExampleViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.recyclerview_pterm,parent,false);
return new ExampleViewHolder(v,mListener);
}
AdapterPTERM(Context context, List<ItemPTERM> exampleList){
mExampleList = exampleList;
mInflater = LayoutInflater.from(context);
}
#Override
public void onBindViewHolder(#NonNull final ExampleViewHolder holder, final int position) {
final ItemPTERM item = mExampleList.get(position);
holder.desc.setText(item.getBtnName());
holder.qta.setText(String.valueOf(item.getQuant()));
holder.variantsContainer.removeAllViews();
// ADDING CHILD HERE
variants = item.getVariants();
if (variants != null && variants.size() > 0){
for(Variant v : variants){
View vView = mInflater.inflate(R.layout.variant_layout,holder.variantsContainer,false);
TextView nameTV = vView.findViewById(R.id.variant_name);
nameTV.setText(v.getName());
vView.setTag(position);
vView.setOnClickListener(varientClickListener);
holder.variantsContainer.addView(vView);
}
}
tvAddItem.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
void onAddItem(true);
}
});
tvRemoveItem.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
void onBtnClickRemoveItem(true);
}
});
// NOT IMPORTANT (CHANGING FIELDS COLOR)
if(position % 2 == 0 ){
holder.itemView.setBackgroundColor(Color.parseColor("#C0C0C0"));
}else if(position % 2 == 1){
holder.itemView.setBackgroundColor(Color.parseColor("#D3D3D3"));
}
}
#Override
public int getItemCount() {
return mExampleList.size();
}
public class ExampleViewHolder extends RecyclerView.ViewHolder {
public TextView desc;
public TextView qta;
private LinearLayout variantsContainer;
ExampleViewHolder(View itemView, final OnItemClickListener listener) {
super(itemView);
desc = itemView.findViewById(R.id.Desc);
qta = itemView.findViewById(R.id.Qta);
variantsContainer = itemView.findViewById(R.id.ll_child_items);
try {
mManageAddRemoveCallbacks = ((ManageAddRemoveCallbacks) this);
} catch (ClassCastException e) {
throw new ClassCastException("ManageAddRemoveCallbacks must implement ManageAddRemoveCallbacksCallback.");
}
itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(listener != null){
int position = getAdapterPosition();
if(position != RecyclerView.NO_POSITION){
listener.onItemClick(position);
}
}
}
});
}
}
public void removeItem(int position) {
mExampleList.remove(position);
notifyItemRemoved(position);
}
public interface ManageAddRemoveCallbacks {
void onAddItem(boolean isAdded);
void onBtnClickRemoveItem(boolean isRemoved);
}
}

You can implement interfaces on their respective click listeners();First go to your adapter and declare an interface like this:
private ManageAddRemoveCallbacks mManageAddRemoveCallbacks ;
public interface ManageAddRemoveCallbacks {
void onAddItem(boolean isAdded);
void onBtnClickRemoveItem(boolean isRemoved);
}
Now in your viewHolder initialize your interface:
try {
this.mManageAddRemoveCallbacks = ((ManageAddRemoveCallbacks) currentFragment);
} catch (ClassCastException e) {
throw new ClassCastException("ManageAddRemoveCallbacks must implement ManageAddRemoveCallbacksCallback.");
}
Now in your bind method where you will add click listeners to your views assign values to your interfaces
tvAddItem.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
void onAddItem(ture or false depending on your requirements);
}
});
tvRemoveItem.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
void onBtnClickRemoveItem(ture or false depending on your requirements);
}
});
Now after doing that you need to implement these interfaces in your activity/fragment something like this:
Your Activity extends AppCompatActivity implements YourAdapter.InterfaceName
so that you can use these. In this way you will get the values in your activity.

Button functionality in Fragment representing a list

In my app I have a Fragment representing a list of items.
This is done using a RecyclerViewAdapter. I have implemented an OnListFragmentInteractionListener and therefore if I click an item in the list my app does something.
That works correctly. However, I decided I want to also add a button inside that item. So if I click anywhere other than the button but inside that item's borders, it will proceed with functionality as before, but if I click on the button, it will do something else.
My question is, where do I implement this functionality?
The XML file representing an item in the list is just a couple of text views and a FloatingActionButton.
I thought I have to implement this in my adapter, but where exactly? My adapter looks like this:
public class ContractRecyclerViewAdapter extends RecyclerView.Adapter<ContractRecyclerViewAdapter.ViewHolder> {
private final List<Contract> mValues;
private final OnListFragmentInteractionListener mListener;
public ContractRecyclerViewAdapter(List<Contract> items, OnListFragmentInteractionListener listener) {
mValues = items;
mListener = listener;
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.fragment_contract_item, parent, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(final ViewHolder holder, int position) {
holder.mItem = mValues.get(position);
holder.mSell.setText(mValues.get(position).getSell());
if (holder.mDescription != null) {
holder.mDescription.setText(mValues.get(position).getDescription());
}
// TODO: Get the price from parameters?
holder.mPrice.setText(((Double) new Random().nextDouble()).toString());
holder.mView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (null != mListener) {
// Notify the active callbacks interface (the activity, if the
// fragment is attached to one) that an item has been selected.
mListener.onListFragmentInteraction(holder.mItem);
}
}
});
holder.mBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
}
});
}
#Override
public int getItemCount() {
return mValues.size();
}
public void addContract(Contract contract) {
mValues.add(contract);
}
public class ViewHolder extends RecyclerView.ViewHolder {
public final View mView;
public final TextView mSell;
public final TextView mDescription;
public final TextView mPrice;
public final FloatingActionButton mBtn;
public Contract mItem;
public ViewHolder(View view) {
super(view);
mView = view;
mSell = (TextView) view.findViewById(R.id.company_text);
mDescription = (TextView) view.findViewById(R.id.contract_description);
mPrice = (TextView) view.findViewById(R.id.price_text);
mBtn = (FloatingActionButton) view.findViewById(R.id.buy_button_from_list);
}
#Override
public String toString() {
return super.toString() + " '" + mSell.getText() + ", " +
mDescription.getText() + "'";
}
}
}
The problem is that wherever I implement the onClickListener for my FloatingActionButton I'll need to have access to my SharedPreferences, so I think I will have to implement it in an Activity class (or Fragment class). Is that true? If I go this way then I'll have to implement it in the Fragment whose content is this view, but then how will I know the position of the item selected?
Thanks.

You can create another method inside your interface,
private interface OnListFragmentInteractionListener {
void onListFragmentInteraction(Contract mItem);
void onButtonClicked(Contract mItem); // You may want to edit the arguments of the method
}
Implement the onButtonClicked in your activity and do your stuff there.
Call the method inside your onClick of the Button as follows,
holder.mBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if (null != mListener) {
mListener.onButtonClicked(holder.mItem);
}
}
});

how will I know the position of the item selected?
To get the position of item selected you can utilize the getAdapterPosition() method of RecyclerView.ViewHolder's class inside your View.OnClickListener.
holder.btnXyz.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
int position = holder.getAdapterPosition();
Model item = items.get(position);
/** your code **/
}
});

How to implement RecycerView With Items having Radio buttons with single choice mode

I need to show a recyclerview with single choice item. but Recyclerview doesn't have the choice mode.
Does any one know how to resolve this?
Thanks in advance.

Store the states of the checked items in a SparseBooleanArray with the position as key.As you change the state of the button,update it's status in the booleanArray and call notifyItemChanged(position).And in BindviewHolder(ViewHolder viewholder,int position) method load the state from booleanArray like viewholder.radioButton.setChecked(boolean.get(position)).Have a look at this for basic idea

You could use something like this, it stores position for selected item, you could add a bit more code to store the item itself if your adapter reorders itself
public class SingleChoiceAdapter extends RecyclerView.Adapter<SingleChoiceAdapter.ItemViewHolder> {
private static final int NO_POSITION = -1;
private static final String SELECTED_ITEM_POSITION = "SELECTED_ITEM_POSITION";
private final LayoutInflater inflater;
private final List<Item> items;
private int selectedItemPosition = NO_POSITION;
public SingleChoiceAdapter(Context context, Bundle savedInstanceState) {
inflater = LayoutInflater.from(context);
items = new ArrayList<>();
if (savedInstanceState != null) {
selectedItemPosition = savedInstanceState.getInt(SELECTED_ITEM_POSITION, NO_POSITION);
}
}
#Override
public ItemViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
final View view = inflater.inflate(R.layout.item, parent, false);
return new ItemViewHolder(view);
}
#Override
public void onBindViewHolder(final ItemViewHolder holder, int position) {
final Item item = items.get(position);
holder.textView.setText(item.name);
holder.textView.setBackgroundColor(position == selectedItemPosition
? Color.LTGRAY
: Color.TRANSPARENT);
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
updateSelectedItem(holder.getAdapterPosition());
}
});
}
#Override
public int getItemCount() {
return items.size();
}
public void setItems(List<Item> items) {
this.items.clear();
this.items.addAll(items);
notifyDataSetChanged();
}
public Item getSelectedItem() {
if (selectedItemPosition == NO_POSITION) {
return null;
}
return items.get(selectedItemPosition);
}
public void onSaveInstanceState(Bundle outState) {
outState.putInt(SELECTED_ITEM_POSITION, selectedItemPosition);
}
private void updateSelectedItem(int newSelectedItemPosition) {
if (selectedItemPosition != NO_POSITION) {
notifyItemChanged(selectedItemPosition);
}
selectedItemPosition = newSelectedItemPosition;
notifyItemChanged(newSelectedItemPosition);
}
public static class ItemViewHolder extends RecyclerView.ViewHolder {
public final TextView textView;
public ItemViewHolder(View itemView) {
super(itemView);
textView = (TextView) itemView.findViewById(R.id.text_view);
}
}
}

Displaying already checks-
You can maintain a boolean array of size of your list. On bind view handle the boolean(true/ false) logic, like setting check true/false of a radio button.
Handling new clicks-
Then on the onclick of the radio button, set the value of every array element to false and setting the current array position to true after that. Now call notifyDatatSetChanged().

You can even do it with just one single integer variable instead of maintaining an array which is costly in devices like android where space is a constraint.
So, just maintain a single integer variable, lets say int selectedPosition=-1 initially.
In onBind check if the position==selectedPosition, if true check the button else uncheck.
Whenever user checks/unchecks the button, just update the selectedPosition
Something like this,
if(selectedPosition==position)
selectedPosition=-1
else{
selectedPosition=position
notifyItemChanged(selectedPosition);
}
notifyItemChanged(position);

Please set the id for the position in onBindViewHolder then you can process action in this method too. Update data set and call notifyDataSetChanged
Here is my example code
#Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
ItemObject itemObject = mDataset.get(position);
((ViewHolder)holder).mTextView.setText(itemObject.getTitle());
Button mButton = ((ViewHolder) holder).mButton;
mButton.setSelected(itemObject.isSelected());
if(itemObject.isSelected()){
((ViewHolder)holder).mTextView.setText("OK");
}
mButton.setTag(position);
mButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
updateDatset((Integer) v.getTag());
}
});
}
In the updateDataset method, I update information of this dataset and call notifyDataSetChanged()
Good luck

Develop Reference

The Android operating system is a mobile operating system that was developed by Google (GOOGL?) to be primarily used for touchscreen devices, cell phones, and tablets.

Is this a wrong way to implement a RecyclerView in Android? - android

Related

Having challenge in RecyclerView item's onClickListener

How to make single selection in recyclerview [duplicate]

How to add/remove child items in a RecyclerView, suggestions for an Order Restaurant App?

Button functionality in Fragment representing a list

How to implement RecycerView With Items having Radio buttons with single choice mode

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