I've got a RecyclerView that needs to update in real-time when content is received. It successfully shows all the content at first load. When attempting to add a new item dynamically, it makes no difference. Is there anything I'm doing wrong here? Much appreciated!
MainActivity:
RecyclerView rvClips;
ClipboardRVAdapter adapter;
ArrayList<Clip> clips = new ArrayList<>();
private void SetupRV() {
adapter = new ClipboardRVAdapter(clips);
rvClips.setAdapter(adapter);
adapter.setClickListener(this);
rvClips.setLayoutManager(new LinearLayoutManager(getActivity()));
}
//this method gets called everytime a new item is received. I confirmed that it gets called.
public void OnNewClipReceived(Clip clip) {
clips.add(0, clip);
adapter.notifyItemInserted(0);
}
Adapter:
Standard adapter code. Simply shows all the items in the recyclerview.
public class ClipboardRVAdapter extends RecyclerView.Adapter<ClipboardRVAdapter.ViewHolder> {
private ItemClickListener mClickListener;
ArrayList<Clip> clips;
public ClipboardRVAdapter(ArrayList<Clip> clips) {
this.clips = clips;
}
public void setClickListener(ItemClickListener itemClickListener) {
this.mClickListener = itemClickListener;
}
public interface ItemClickListener {
void onItemClick(View view, int position);
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
Context context = parent.getContext();
LayoutInflater inflater = LayoutInflater.from(context);
// Inflate the custom layout
View contactView = inflater.inflate(R.layout.item_clipboard_clip, parent, false);
// Return a new holder instance
ViewHolder viewHolder = new ViewHolder(contactView);
return viewHolder;
}
#Override
public void onBindViewHolder(#NonNull ViewHolder holder, int position) {
Clip clip = clips.get(position);
holder.tvClipTitle.setText(clip.content);
}
#Override
public int getItemCount() {
return clips.size();
}
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
public TextView tvClipTitle;
public ViewHolder(View itemView) {
super(itemView);
tvClipTitle = itemView.findViewById(R.id.tvClipTitle);
}
#Override
public void onClick(View view) {
if (mClickListener != null) mClickListener.onItemClick(view, getAdapterPosition());
}
}
}
Since you mentioned 'realtime', I'm guessing this could be a thread issue. Your code seems correct. It could be that the adapter needs to be refreshed in a runOnUiThread function. Try this:
public void OnNewClipReceived(Clip clip) {
getActivity().runOnUiThread(new Runnable() {
#Override
public void run() {
clips.add(0, clip);
adapter.notifyItemInserted(0);
}
});
}
You would need this method in your RecyclerView adapter.
void addNewClip(Clip clip, int index) {
this.clips.add(index, clip);
notifyItemInserted(index);
}
Adding to clips(MainActivity's) won't make a difference because your adapter has it own ArrayList to work with.
Good day, I want to pass position from RecyclerView's adapter to MainActivity, so I design a interface:
in RecyclerViewAdapter:
publuc interface recyclerViewAdapterListener{
void onDeviceConnect(data, position)
}
public void onBindViewHolder(#NonNull ViewHolder holder, int position) {
//here I call onDeviceConnect
holder.button.setOnClickListener(new View.OnClickListener(){
public void onClick(View view) {
listener.onDeviceConnect(data, position);
}
in MainActicity:
private int pos;
public void onDeviceConnect(data,position){
pos = position;
}
I know the problem is pos = position, that will be always get the last position.
but I need data and position from RecyclerView, because when my device connected,
It will change RecyclerView's item.
ex : (in MainActivity)
case BleService.ACTION_NOTIFY_ON: //here my device is connected.
updateStatus(mac,status); //update status
private void updateStatus(mac,status){
Adapter.updateItem(data, pos); //call adapter's item
}
ex : (in RecyclerViewAdapter)
public void updateItem(data,pos){
if (dataList.size() != 0){
dataList.set(pos, data);
notifyItemChanged(pos);
}
is any good idea can fix it , Thanks.
in MainActicity:
`
public class MainActicity extends AppCompatActivity implements YourRecyleAdaptor.recyclerViewAdapterListener{
private int pos;
#Override
public void onDeviceConnect(data,position){
pos = position;
}
`
Try to replace the position with holder.getAdapterPosition()
public void onBindViewHolder(#NonNull ViewHolder holder, int position) {
//here I call onDeviceConnect
holder.button.setOnClickListener(new View.OnClickListener(){
public void onClick(View view) {
listener.onDeviceConnect(data, holder.getAdapterPosition());
}
Or you can also setOnClickListener in the constructor of the ViewHolder class
Problem
In my acitvity i have two recyclerViews showing popular movies and top rated movies respectively.
When I click on a movie in a recyclerView, that movie is sent to an activity showing its details.
I go back to the home and if I click on a movie of another recyclerView, the previously clicked movie is shown.
I need to show the details of any clicked movie in any recyclerView.
I have a single viewHolder (MovieViewHolder)
public class MovieViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
//Widgets
TextView title, rating;
ImageView imageView;
//Click listener
OnMovieListener onMovieListener ;
public MovieViewHolder(#NonNull View itemView, OnMovieListener onMovieListener) {
super(itemView);
this.onMovieListener = onMovieListener;
title = itemView.findViewById(R.id.movie_title);
imageView = itemView.findViewById(R.id.movie_img);
rating = itemView.findViewById(R.id.rating_bar);
itemView.setOnClickListener(this);
}
#Override
public void onClick(View v) {
onMovieListener.onMovieClick(getAdapterPosition());
}
An interface
public interface OnMovieListener {
void onMovieClick(int position);
void onCategoryClick(String category);
}
This two Adapter:
This for popular movies
public class MovieRecyclerView extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private List<MovieModel> mMovies;
private final OnMovieListener onMovieListener;
public MovieRecyclerView(OnMovieListener onMovieListener) {
this.onMovieListener = onMovieListener;
}
#NonNull
#Override
public RecyclerView.ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.movie_item,
parent, false);
return new MovieViewHolder(view, onMovieListener);
}
#Override
public void onBindViewHolder(#NonNull RecyclerView.ViewHolder holder, int position) {
((MovieViewHolder) holder).title.setText(mMovies.get(position).getTitle());
((MovieViewHolder) holder).rating.setText(String.valueOf((float) (mMovies.get(position).getVote_average())));
//ImageView: Using Glide Library
Glide.with(holder.itemView.getContext())
.load("https://image.tmdb.org/t/p/w500/"
+ mMovies.get(position).getPoster_path())
.into(((MovieViewHolder) holder).imageView);
}
#Override
public int getItemCount() {
if (mMovies != null) {
return mMovies.size();
}
return 0;
}
public void setmMovies(List<MovieModel> mMovies) {
this.mMovies = mMovies;
notifyDataSetChanged();
}
//Getting the id of the movie clicked
public MovieModel getSelectedMovie(int position) {
if (mMovies != null) {
if (mMovies.size() > 0) {
return mMovies.get(position);
}
}
return null;
}
This for top_rated
public class MovieLatestRecyclerView extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private List<MovieModel> mMoviesLatest;
private OnMovieListener onMovieListener;
public MovieLatestRecyclerView(OnMovieListener onMovieListener) {
this.onMovieListener = onMovieListener;
}
#NonNull
#Override
public RecyclerView.ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.movie_item,
parent, false);
return new MovieViewHolder(view, onMovieListener);
}
#Override
public void onBindViewHolder(#NonNull RecyclerView.ViewHolder holder, int position) {
((MovieViewHolder)holder).title.setText(mMoviesLatest.get(position).getTitle());
((MovieViewHolder)holder).rating.setText(String.valueOf((float) (mMoviesLatest.get(position).getVote_average())));
//ImageView: Using Glide Library
Glide.with(holder.itemView.getContext())
.load("https://image.tmdb.org/t/p/w500/"
+ mMoviesLatest.get(position).getPoster_path())
.into(((MovieViewHolder)holder).imageView);
}
#Override
public int getItemCount() {
if(mMoviesLatest != null) {
return mMoviesLatest.size();
}
return 0;
}
public void setmMoviesLatest(List<MovieModel> mMoviesLatest) {
this.mMoviesLatest = mMoviesLatest;
notifyDataSetChanged();
}
//Getting the id of the movie clicked
public MovieModel getSelectedMovie(int position){
if(mMoviesLatest != null){
if(mMoviesLatest.size() > 0){
return mMoviesLatest.get(position);
}
}
return null;
}
In MainActivity i configure the recyclerViews with this method
private void ConfigureRecyclerView() {
movieRecyclerViewAdapter = new MovieRecyclerView(this);
movieLatestRecyclerViewAdapter = new MovieLatestRecyclerView(this);
recyclerView_popular.setAdapter(movieRecyclerViewAdapter);
recyclerView_popular.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false));
recyclerView_latest.setAdapter(movieLatestRecyclerViewAdapter);
recyclerView_latest.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false));
//RecyclerView Pagination
//Loading next page of api response
recyclerView_popular.addOnScrollListener(new RecyclerView.OnScrollListener() {
#Override
public void onScrollStateChanged(#NonNull RecyclerView recyclerView, int newState) {
if (!recyclerView.canScrollVertically(1)) {
//Here we need to display the next search result
movieListViewModel.searchNextPage();
}
}
});
recyclerView_latest.addOnScrollListener(new RecyclerView.OnScrollListener() {
#Override
public void onScrollStateChanged(#NonNull RecyclerView recyclerView, int newState) {
if (!recyclerView.canScrollVertically(1)) {
//Here we need to display the next search result
movieListViewModel.searchNextPage();
}
}
});
}
And i use this for passing the selected movie to another activity
#Override
public void onMovieClick(int position) {
//WE don't need position of the movie in recyclerView
// We need the ID of the movie in order to get all it's details
Intent intent = new Intent(this, MovieDetails.class);
intent.putExtra("movie", movieRecyclerViewAdapter.getSelectedMovie(position));
startActivity(intent);
}
Whoever you are reading my question I thank you for your time and I apologize for the certain banality and length.
At this line:
intent.putExtra("movie", movieRecyclerViewAdapter.getSelectedMovie(position));
You are getting a movie from movieRecyclerViewAdapter. This adapter is only used with the 'Popular' movie recycler view.
onMovieClick is used for both the 'Popular' and the 'Top Rated' recycler views. So, clicking an item from 'Top Rated' will attempt to use an item from 'Popular'.
To fix this, a click from 'Top Rated' should not attempt to get an item from movieRecyclerViewAdapter.
You could do something like change onMovieClick(int position) to onMovieClick(MovieModel movie), so you don't have to worry about knowing which adapter to get the movie from.
I use RecyclerView adapter to display data inside an activity, I want to implement onClickListener inside the activity, currently, I am setting onClickListener inside adapter as usual which works fine.
public void onBindViewHolder(MyHolder holder, final int position) {
final Listdata data = listdata.get(position);
holder.vname.setText(data.getName());
holder.vname.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Toast.makeText(activity, "clicked on " +position, Toast.LENGTH_SHORT).show();
}
});
}
However I want to implement it inside activity so I have greater control. This doesn't serve my purpose. I think it'll be useful for a lot of us.
You need to check this tutorial here for better understanding on how you can achieve the behaviour that you want.
In case of handling the onClickListener from your activity you need to work based on a callback implementation with an interface. Pass the interface from the activity to your adapter and then call the callback function from your adapter when some items are clicked.
Here's a sample implementation from the tutorial.
Let us first have the interface.
public interface OnItemClickListener {
void onItemClick(ContentItem item);
}
You need to modify your adapter to take the listener as the parameter like the one stated below.
private final List<ContentItem> items;
private final OnItemClickListener listener;
public ContentAdapter(List<ContentItem> items, OnItemClickListener listener) {
this.items = items;
this.listener = listener;
}
Now in your onBindViewHolder method, set the click listener.
#Override public void onBindViewHolder(ViewHolder holder, int position) {
holder.bind(items.get(position), listener);
}
public void bind(final ContentItem item, final OnItemClickListener listener) {
...
itemView.setOnClickListener(new View.OnClickListener() {
#Override public void onClick(View v) {
listener.onItemClick(item);
}
});
}
Now setting the adapter in your RecyclerView.
recycler.setAdapter(new ContentAdapter(items, new ContentAdapter.OnItemClickListener() {
#Override public void onItemClick(ContentItem item) {
Toast.makeText(getContext(), "Item Clicked", Toast.LENGTH_LONG).show();
}
}));
So the whole adapter code looks like the following.
public class ContentAdapter extends RecyclerView.Adapter<ContentAdapter.ViewHolder> {
public interface OnItemClickListener {
void onItemClick(ContentItem item);
}
private final List<ContentItem> items;
private final OnItemClickListener listener;
public ContentAdapter(List<ContentItem> items, OnItemClickListener listener) {
this.items = items;
this.listener = listener;
}
#Override public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.view_item, parent, false);
return new ViewHolder(v);
}
#Override public void onBindViewHolder(ViewHolder holder, int position) {
holder.bind(items.get(position), listener);
}
#Override public int getItemCount() {
return items.size();
}
static class ViewHolder extends RecyclerView.ViewHolder {
private TextView name;
private ImageView image;
public ViewHolder(View itemView) {
super(itemView);
name = (TextView) itemView.findViewById(R.id.name);
image = (ImageView) itemView.findViewById(R.id.image);
}
public void bind(final ContentItem item, final OnItemClickListener listener) {
name.setText(item.name);
Picasso.with(itemView.getContext()).load(item.imageUrl).into(image);
itemView.setOnClickListener(new View.OnClickListener() {
#Override public void onClick(View v) {
listener.onItemClick(item);
}
});
}
}
}
Registering clickListener inside onCreateViewHolder instead of onBindViewHolder is more performant since you only add listener when a view is created not ever time recyclerView is scrolled.
And i use ListAdapter with DiffUtil callback instead of RecyclerViewAdapter
abstract class BaseListAdapter<ItemType>(
callBack: DiffUtil.ItemCallback<ItemType> = DefaultItemDiffCallback(),
private inline val onItemClicked: ((ItemType, Int) -> Unit)? = null
) : ListAdapter<ItemType, BaseItemViewHolder>(
AsyncDifferConfig.Builder<ItemType>(callBack)
.setBackgroundThreadExecutor(Executors.newSingleThreadExecutor())
.build()
) {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): BaseItemViewHolder {
return BaseItemViewHolder(
DataBindingUtil.inflate(
LayoutInflater.from(parent.context),
getLayoutRes(viewType),
parent, false
)
).apply {
onViewHolderCreated(this, viewType, binding)
}
}
fun createCustomViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
return BaseItemViewHolder(
DataBindingUtil.inflate(
LayoutInflater.from(parent.context),
getLayoutRes(viewType),
parent, false
)
)
}
override fun onBindViewHolder(
holder: BaseItemViewHolder,
position: Int,
payloads: MutableList<Any>
) {
val item: ItemType? = currentList.getOrNull(position)
item?.let {
holder.binding.setVariable(BR.item, item)
onViewHolderBound(holder.binding, item, position, payloads)
holder.binding.executePendingBindings()
}
}
override fun onBindViewHolder(holder: BaseItemViewHolder, position: Int) {
}
/**
* get layout res based on view type
*/
protected abstract fun getLayoutRes(viewType: Int): Int
/**
* Called when a ViewHolder is created. ViewHolder is either created first time or
* when data is refreshed.
*
* This method is not called when RecyclerView is being scrolled
*/
open fun onViewHolderCreated(
viewHolder: RecyclerView.ViewHolder,
viewType: Int,
binding: ViewDataBinding
) {
binding.root.setOnClickListener {
onItemClicked?.invoke(getItem(viewHolder.bindingAdapterPosition), viewHolder.bindingAdapterPosition)
}
}
/**
* bind view while RecyclerView is being scrolled and new items are bound
*/
open fun onViewHolderBound(
binding: ViewDataBinding,
item: ItemType,
position: Int,
payloads: MutableList<Any>
) {
}
}
open class BaseItemViewHolder(
val binding: ViewDataBinding
) : RecyclerView.ViewHolder(binding.root)
class DefaultItemDiffCallback<ItemType> : DiffUtil.ItemCallback<ItemType>() {
override fun areItemsTheSame(
oldItem: ItemType,
newItem: ItemType
): Boolean {
return oldItem === newItem
}
override fun areContentsTheSame(
oldItem: ItemType,
newItem: ItemType
): Boolean {
return oldItem.hashCode() == newItem.hashCode()
}
}
Another better user experience is using onBindViewHolder with payLoad which lets you only update some part of the rows instead of whole row. For instance you have image, title and body in rows, and only body changes frequently, without payload image flashes and provides bad user experience. But with payload you can decide which part of the row should be updated allowing you not to reload parts that were not updated.
very simple and clean solution is:
create a class with the name of RecyclerTouchListener:
public class RecyclerTouchListener implements RecyclerView.OnItemTouchListener {
private GestureDetector gestureDetector;
private ClickListener clickListener;
public RecyclerTouchListener(Context context, final RecyclerView recyclerView, final ClickListener clickListener) {
this.clickListener = clickListener;
gestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
#Override
public boolean onSingleTapUp(MotionEvent e) {
return true;
}
#Override
public void onLongPress(MotionEvent e) {
View child = recyclerView.findChildViewUnder(e.getX(), e.getY());
if (child != null && clickListener != null) {
clickListener.onLongClick(child, recyclerView.getChildPosition(child));
}
}
});
}
#Override
public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {
View child = rv.findChildViewUnder(e.getX(), e.getY());
if (child != null && clickListener != null && gestureDetector.onTouchEvent(e)) {
clickListener.onClick(child, rv.getChildPosition(child));
}
return false;
}
#Override
public void onTouchEvent(RecyclerView rv, MotionEvent e) {
}
#Override
public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) {
}
public interface ClickListener {
void onClick(View view, int position);
void onLongClick(View view, int position);
}
}
in your recyclerview activity:
recyclerView.addOnItemTouchListener(new RecyclerTouchListener(getApplicationContext(), recyclerView, new RecyclerTouchListener.ClickListener() {
#Override
public void onClick(View view, int position) {
speech(countries_list_code[position]);
}
#Override
public void onLongClick(View view, int position) {
}
}));
I found super duper easy method! I recommend this one
Example Code:
public class ContentAdapter extends RecyclerView.Adapter<ContentAdapter.ViewHolder> {
public interface OnItemClickListener {
void onItemClick(ContentItem item);
}
private final List<ContentItem> items;
private final OnItemClickListener listener;
public ContentAdapter(List<ContentItem> items, OnItemClickListener listener) {
this.items = items;
this.listener = listener;
}
#Override public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.view_item, parent, false);
return new ViewHolder(v);
}
#Override public void onBindViewHolder(ViewHolder holder, int position) {
holder.bind(items.get(position), listener);
}
#Override public int getItemCount() {
return items.size();
}
static class ViewHolder extends RecyclerView.ViewHolder {
private TextView name;
private ImageView image;
public ViewHolder(View itemView) {
super(itemView);
name = (TextView) itemView.findViewById(R.id.name);
image = (ImageView) itemView.findViewById(R.id.image);
}
public void bind(final ContentItem item, final OnItemClickListener listener) {
name.setText(item.name);
Picasso.with(itemView.getContext()).load(item.imageUrl).into(image);
itemView.setOnClickListener(new View.OnClickListener() {
#Override public void onClick(View v) {
listener.onItemClick(item);
}
});
}
}
}
And Use RecyclerView Adapter using below code:
recycler.setAdapter(new ContentAdapter(items, new ContentAdapter.OnItemClickListener() {
#Override public void onItemClick(ContentItem item) {
Toast.makeText(getContext(), "Item Clicked", Toast.LENGTH_LONG).show();
}
}));
i found this from here
Hope it helped you.
In my way, I just created a single instance of ClickListener, And it dispatches click event to both RecyclerView and Activity or Fragment:
class LeagueAdapter(
onLeagueSelected: (League, Int, View) -> Unit
) : RecyclerView.Adapter<LeagueHolder>() {
private val dataSet = arrayListOf<League>()
private val clickListener = View.OnClickListener { view ->
val adapterPosition = view.tag as Int
onLeagueSelected(dataSet[adapterPosition], adapterPosition, view)
// perform adapter related action here ...
}
override fun getItemCount(): Int {
return dataSet.size
}
override fun onBindViewHolder(holder: LeagueHolder, position: Int) {
// put item position in tag field
holder.itemView.tag = position
holder.itemView.setOnClickListener(clickListener)
}
}
And inside Activity, we have something like this:
private val headerAdapter = LeagueAdapter { league, i, view ->
Log.e(TAG, "item clicked $i")
}
Create an interface for the adapter class
private OnItemClickListener mListener;
public CustomAdapter(List<Listdata> listdata, OnItemClickListener listener) {
mListener = listener;
...
...
}
private class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
ViewHolder(View view) {
...
...
view.setOnClickLister(this);
}
#override
public void onClick(View v) {
mListener.onAdapterItemClick(getAdapterPosition())
}
}
interface OnItemClickListener {
void onAdapterItemClick(int position);
}
Let the activity implement the interface
public class CustomListActivity extends AppCompatActivity implements OnItemClickListener {
...
...
#override
public void onAdapterItemClick(int position) {
Toast.makeText(activity, "clicked on " +position, Toast.LENGTH_SHORT).show();
}
There is another way of doing this, check out this implementation
You can let your Activity implements View.OnClickListener and pass it to adapter. Below is an example.
class RAdapter extends RecyclerView.Adapter<>{
View.OnClickListener listner;
public RAdapter(View.OnClickListener listner) {
this.listner = listner;
}
public void onBindViewHolder(MyHolder holder, final int position) {
holder.vname.setOnClickListener(listner);
}
}
But to handle click in Activity you will going to need clicked position. You can have it with adapter.getAdapterPosition() to validate which item is clicked.
Apart from that To pass click event to the Fragment/Activity you can use a Custom callback listener this way your Adapter will be reusable .
A better way to handle clicks in ViewHolder. See the below example.
class Holder extends RecyclerView.ViewHolder implements View.OnClickListener {
Button button;
public Holder(View itemView) {
super(itemView);
button=itemView.findViewById(R.id.b1);
button.setOnClickListener(this);
}
#Override
public void onClick(View v) {
if(v.getId()==R.id.b1){
int position=getAdapterPosition();
// Call the call method here
// with position or data Object itself
}
}
}
If I understood correctly you want to set the on click logic in the Activity.
You can do this by setting the OnClickListener in the Activity and passing it in the Adapter constructor.
MyAdapter myAdapter = new MyAdapter(new View.OnClickListener() {
#Override
public void onClick(View view) {
Toast.makeText(activity, "clicked on " +position, Toast.LENGTH_SHORT).show();
}
}));
And your MyAdapter Constructor would be:
final private OnClickListener onClickListener;
public MyAdapter(OnClickListener onClickListener) {
this.OnClickListener = OnClickListener;
}
So your new code would be something like this
public void onBindViewHolder(MyHolder holder, final int position) {
final Listdata data = listdata.get(position);
holder.vname.setText(data.getName());
holder.vname.setOnClickListener(onClickListener);
}
RecyclerView widget only has 2 useful listeners for this scenario:
RecyclerView.OnChildAttachStateChangeListener - covered here
RecyclerView.OnItemTouchListener - the one that I will be covering
the code is inspired by TouchEvents sample related to Accessibility, and works in Activity/Fragment without setting any listeners in the Adapter
recyclerView.addOnItemTouchListener(object : RecyclerView.SimpleOnItemTouchListener() {
var downTouch = false
override fun onInterceptTouchEvent(rv: RecyclerView, e: MotionEvent): Boolean {
when (e.action) {
MotionEvent.ACTION_DOWN -> downTouch = true
MotionEvent.ACTION_UP -> if (downTouch) {
downTouch = false
recyclerView.findChildViewUnder(e.x, e.y)?.let {
val position = rv.getChildAdapterPosition(it)
Toast.makeText(rv.context, "clicked on $position", Toast.LENGTH_SHORT)
.show()
}
}
else -> downTouch = false
}
return super.onInterceptTouchEvent(rv, e)
}
})
There's another very simple way documented in CodePath.
ItemClickSupport.addTo(recyclerView).setOnItemClickListener(
new ItemClickSupport.OnItemClickListener() {
#Override
public void onItemClicked(RecyclerView recyclerView, int position, View v) {
// do stuff
}
}
);
The implementation of ItemClickSupport.
Personally, I like to handle this via RxJava subjects:
A Subject is a sort of bridge or proxy that is available in some implementations of ReactiveX that acts both as an observer and as an Observable. Because it is an observer, it can subscribe to one or more Observables, and because it is an Observable, it can pass through the items it observes by re-emitting them, and it can also emit new items.
For more info read Understanding RxJava Subject — Publish, Replay, Behavior and Async Subject.
in Adapter:
public static PublishSubject<MyData> onClickSubject = PublishSubject.create();
ViewHolder:
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
.
.
.
#Override
public void onClick(View view) {
onClickSubject.onNext(getItem(getAdapterPosition()));
}
}
Add your disposables to a CompositeDisposable and dispose them in onDestroy():
private CompositeDisposable compositeDisposable = new CompositeDisposable();
in onCreate():
compositeDisposable.add(MyAdapter.onClickSubject.subscribe(myData -> {
//do something here
}));
in onDestroy():
compositeDisposable.dispose();
Note:
1. getItem() is a method of androidx.recyclerview.widget.ListAdapter and androidx.paging.PagedListAdapter if you are extending RecyclerView.Adapter you can get item from your data list by position.
2. to use Disposables you need RxJava2 or above
Kotlin
I'd better to add item click in onCreateViewHolder like this
override fun onCreateViewHolder(viewGroup: ViewGroup, viewType: Int):
ProductViewHolder {
val view: View = LayoutInflater.from(viewGroup.context)
.inflate(R.layout.layout_product_item, viewGroup, false)
return ProductViewHolder(view).also { viewHolder ->
viewHolder.itemView.setOnClickListener {
val position = viewHolder.layoutPosition
if (position != RecyclerView.NO_POSITION) {
// do what you want with data[position]
}
}
}
}
You can implement the View.OnClickListener interface in your RecyclerView.ViewHolder class and call it from there.
In your Adapter class create a public interface.
public void setOnItemClickListener(OnItemClickListener onItemClickListener) {
this.onItemClickListener = onItemClickListener;
}
public interface OnItemClickListener {
void onItemClick(int position);
}
private OnItemClickListener onItemClickListener;
On your ViewHolder class, you can implement the View.OnClickListener interface and set an onclick listener to the itemView.
public class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
public TextView myText;
public WalletViewHolder(#NonNull View itemView) {
super(itemView);
myText= itemView.findViewById(R.id.my_text_view);
// Set click listener for each item view
itemView.setOnClickListener(this);
}
#Override
public void onClick(View view) {
if (onItemClickListener != null) {
onItemClickListener.onItemClick(getAdapterPosition());
}
}
}
Then your OnItemClickListener will be created only once.
I always have one Generic Adapter in my project to avoid make a Adapter class every I use a Recyclerview. Here some example
public class AdapterRecyclerviewTextOnly extends RecyclerView.Adapter<AdapterRecyclerviewTextOnly.ViewHolder> {
private RecyclerView recyclerView;
private OnRecyclerviewListener onRecyclerviewListener;
public interface OnRecyclerviewListener {
void onRecyclerviewBind(RecyclerView recyclerView, AdapterRecyclerviewTextOnly.ViewHolder viewHolder, int position);
void onRecyclerviewClick(RecyclerView recyclerView, int position);
int onItemCount(RecyclerView recyclerView);
}
public void setOnRecyclerviewListener(OnRecyclerviewListener listener) { this.onRecyclerviewListener = listener; }
public AdapterRecyclerviewTextOnly(RecyclerView recyclerView) {
super();
this.recyclerView = recyclerView;
}
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
RecyclerView recyclerView;
public TextView textView;
ViewHolder(RecyclerView recyclerView, View itemView) {
super(itemView);
this.recyclerView = recyclerView;
this.itemView.setOnClickListener(this);
this.textView = itemView.findViewById(R.id.textview_title);
}
void onBind(int position) { onRecyclerviewListener.onRecyclerviewBind(this.recyclerView, this, position); }
#Override
public void onClick(View v) {
onRecyclerviewListener.onRecyclerviewClick(this.recyclerView, getAdapterPosition());
}
}
#Override
public AdapterRecyclerviewTextOnly.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View inflatedView = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_recyclerview_text_only, parent, false);
return new ViewHolder(this.recyclerView, inflatedView);
}
#Override
public void onBindViewHolder(AdapterRecyclerviewTextOnly.ViewHolder holder, int position) {
holder.onBind(position);
}
#Override
public int getItemCount() {
return onRecyclerviewListener.onItemCount(this.recyclerView);
}
}
And then in your Activity Class, you can use this adapter with :
this.recyclerView = findViewById(R.id.recyclerview);
this.recyclerView.setHasFixedSize(true);
this.recyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false));
AdapterRecyclerviewTextOnly recyclerViewAdapter = new AdapterRecyclerviewTextOnly(this.recyclerView);
this.recyclerView.setAdapter(this.recyclerViewAdapter);
this.recyclerViewAdapter.setOnRecyclerviewListener(new AdapterRecyclerviewTextOnly.OnRecyclerviewListener() {
#Override
public void onRecyclerviewBind(RecyclerView recyclerView, AdapterRecyclerviewTextOnly.ViewHolder viewHolder, int position) {
}
#Override
public void onRecyclerviewClick(RecyclerView recyclerView, int position) {
}
#Override
public int onItemCount(RecyclerView recyclerView) {
}
});
You can reuse this with 2 or 3 recyclerview too.
First, declare a globar listener private AdapterRecyclerviewTextOnly.OnRecyclerviewListener listener;.
Then init the listener with new object then set the your every recyclerview with the listener. Use specific identifier:
if (recyclerView == recyclerViewA){ } else if (recyclerView == recyclerViewB) { } to manage your recyclerview inside the adapter.
I have a recyclerView behanving like a list, how do I change the background color of only one view? The item I want to change the color's ID is "1", I thought about getting it in the activity by it's ID and add it a decorator, but I don't know how to, or if it's even possible.
Inside the adapter:
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
holder.setEventNameName(i + "");
holder.settheColor(Color.parseColor("#000000"));
}
static int i;
class ViewHolder extends RecyclerView.ViewHolder{
public TextView eventName;
public RelativeLayout theLayout;
public ViewHolder(final View itemView) {
super(itemView);
eventName = (TextView)itemView.findViewById(R.id.eventName);
theLayout = (RelativeLayout)itemView.findViewById(R.id.backgroundevent);
theLayout.setId(++i);
theLayout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (getAdapterPosition()>0){
removeItem(getAdapterPosition());
}else {
addItem("");
}
}
});
}
public void settheColor(int theColor){
theLayout.setBackgroundColor(Color.parseColor(String.valueOf(theColor)));
}
public void setEventNameName(String TheEventName){
eventName.setText(TheEventName);
}
}
I feel you can do it in this way --
#Override
public void onBindViewHolder(MyViewHolder holder, int position) {
currentListItem = List.get(position);
if(position == 0) //this will let you know the first child item
{
holder.textview.setBackgroundColor(Color.RED);
}
}
Hope this helps!
Pretty simple, use the onBindViewHolder method of your adapter, and change the color of the view (which should be referenced in your ViewHolder)
Follow this example if you are new to the Recyclerview concept.