Develop Reference

How to Call Interface method from Xml using Data Binding?

Here's my Fragment:
public class Fragment_Cities extends Fragment implements Adapter_Cities.CitiesListener {
private Adapter_Cities adapterCities;
private FragmentCitiesBinding binding;
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
binding = FragmentCitiesBinding.inflate(inflater, container, false);
return binding.getRoot();
}
#Override
public void onViewCreated(#NonNull View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
binding.recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
adapterCities = new Adapter_Cities(this);
binding.recyclerView.setAdapter(adapterCities);
ViewModel_Cities viewModelCities = new ViewModelProvider(this).get(ViewModel_Cities.class);
viewModelCities.getLiveDataCities().observe(getViewLifecycleOwner(), model_cities ->
adapterCities.setAdapterData(model_cities));
}
#Override
public void onCitySelected(Model_Cities city) {
if (!alertDialog.isShowing()) alertDialog.show();
new DialogFragment_Map().newInstance(city.getName(), city.getLatLon(), this).
show(requireActivity().getSupportFragmentManager(), null);
}
}
**
Here's my Adapter:
**
public class Adapter_Cities extends RecyclerView.Adapter<Adapter_Cities.MyViewHolder> implements Filterable {
private List<Model_Cities> cityList, cityListFiltered;
public CitiesListener citiesListener;
public class MyViewHolder extends RecyclerView.ViewHolder {
private final RowCityBinding rowCityBinding;
public MyViewHolder(View itemView) {
super(itemView);
rowCityBinding = RowCityBinding.bind(itemView);
// itemView.setOnClickListener(v -> recyclerViewItemClickListener.onCitySelected(cityListFiltered.get(getBindingAdapterPosition())));
}
}
public Adapter_Cities(CitiesListener citiesListener) {
this.citiesListener = citiesListener;
}
#NonNull
#Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_city, parent, false);
return new MyViewHolder(itemView);
}
#Override
public void onBindViewHolder(Adapter_Cities.MyViewHolder holder, int position) {
holder.rowCityBinding.setModel(cityListFiltered.get(position));
holder.rowCityBinding.executePendingBindings();
}
public void setAdapterData(List<Model_Cities> cityList) {
this.cityList = cityList;
this.cityListFiltered = cityList;
notifyDataSetChanged();
}
#Override
public int getItemCount() {
return cityListFiltered == null ? 0 : cityListFiltered.size();
}
public interface CitiesListener {
void onCitySelected(Model_Cities city);
}
}
**
Here's my XML Layout:
**
<data>
<variable
name="callback"
type="com.base.assignment.adapters.Adapter_Cities.CitiesListener" />
<variable
name="model"
type="com.base.assignment.models.Model_Cities" />
</data>
<androidx.cardview.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="15dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="15dp"
android:background="#color/white"
android:onClick="#{()->callback.onCitySelected(model)}">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:padding="10dp">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#{model.title}"
android:textColor="#color/black"
android:textSize="15sp"
android:textStyle="bold" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#{model.subTitle}"
android:textColor="#color/black"
android:textSize="12sp" />
</LinearLayout>
</androidx.cardview.widget.CardView>
**
Here's the result i got:
**
My actual requirement is when user clicks on RecyclerView Item, the app must show a DialogFragment which should be called by a Fragment. So, I'm trying to trigger onClick of RecyclerView layout through XML, and the action that should happen on clicking is -> The information of clicked item should be sent to Fragment with Model Object as it's parameter.
Whereas When I clicked on Recyclerview Item no action is been happening. No crashes, no information in logcat, no updates in App UI.
As DataBinding shows the Compile time errors, i am seeing the below errors:
And right to it, i see the code details of the issue (as attached below):

For that set your listener interface for layout within onBindViewHolder().
#Override
public void onBindViewHolder(Adapter_Cities.MyViewHolder holder, int position) {
holder.rowCityBinding.setCallback(citiesListener);
holder.rowCityBinding.setModel(cityListFiltered.get(position));
holder.rowCityBinding.executePendingBindings();
}

RecyclerView not counting above 10

My RecyclerView does not count above 10 items. After the 10th item, it shows item 9 again and then item 1 and 2.
This RecyclerView produces the bug:
mViewModel.getmPremixableIngredientsLive().observe(getViewLifecycleOwner(), new Observer<ArrayList<Ingredient>>() {
#Override
public void onChanged(ArrayList<Ingredient> premixableIngredients) {
ShowIngredientsRecyclerViewAdapter premixableComponentsRecyclerViewAdpater = new ShowIngredientsRecyclerViewAdapter(premixableIngredients);
mBinding.premixableIngredientsRecyclerview.setAdapter(premixableComponentsRecyclerViewAdpater);
GridLayoutManager gridLayoutManager = new GridLayoutManager(getContext(), 1);
mBinding.premixableIngredientsRecyclerview.setLayoutManager(gridLayoutManager);
}
});
This is the code of my adapter:
public class ShowIngredientsRecyclerViewAdapter extends RecyclerView.Adapter<ShowIngredientsRecyclerViewAdapter.ViewHolder> {
private ArrayList<Ingredient> mIngredients;
private IngredientRecyclerViewItemBinding mBinding;
public ShowIngredientsRecyclerViewAdapter(ArrayList<Ingredient> ingredients) {
mIngredients = ingredients;
}
#NonNull
#Override
public ShowIngredientsRecyclerViewAdapter.ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
mBinding = DataBindingUtil.inflate(
LayoutInflater.from(parent.getContext()),
R.layout.ingredient_recycler_view_item,
parent,
false
);
return new ViewHolder(mBinding.getRoot());
}
#Override
public void onBindViewHolder(#NonNull ShowIngredientsRecyclerViewAdapter.ViewHolder holder, int position) {
mBinding.position.setText((position + 1) + ".");
mBinding.componentName.setText(mIngredients.get(position).getmComponent().getmName());
mBinding.amount.setText((mIngredients.get(position).getGrammPerCow() / 1000) + "kg/cow");
mBinding.dragBtn.setVisibility(View.GONE);
}
#Override
public int getItemCount() {
return mIngredients.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
public ViewHolder(#NonNull View itemView) {
super(itemView);
}
}
}
xml layout for the item:
<?xml version="1.0" encoding="utf-8"?>
<layout
xmlns:android="http://schemas.android.com/apk/res/android">
<LinearLayout
android:id="#+id/ingredient_recyclerview_item_linearLayout"
android:background="?android:attr/selectableItemBackground"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="8dp"
android:paddingLeft="0dp"
android:paddingStart="0dp">
<TextView
android:id="#+id/position"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="1"/>
<TextView
android:id="#+id/component_name"
android:layout_width="0dp"
android:layout_weight="1"
android:layout_height="wrap_content"
android:text="Component 1"/>
<TextView
android:id="#+id/amount"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="50kg"/>
<ImageButton
android:id="#+id/drag_btn"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:src="#drawable/ic_drag_grey"
android:background="#android:color/transparent"
android:layout_marginStart="8dp"/>
</LinearLayout>
</layout>

You are not implementing databinding correctly in your recyclerview. You shouldn't declare mBinding as a global variable in the adapter. Instead, it should be a global variable in the custom viewholder class. I share an example recyclerview adapter code with databinding below. You can adapt it to your case. Notice that binding is not a global variable in the adapter, but in the custom viewholder. And the viewholder accept binding as argument, so we pass binding instance to the viewholder when we create the viewholder and we use that instance when onBindViewHolder is called.
public class ProductAdapter extends RecyclerView.Adapter<ProductAdapter.ProductViewHolder> {
private final List<Product> mProductList;
private final ProductItemClickListener mListener;
ProductAdapter(#NonNull List<Product> productList, ProductItemClickListener listener) {
mProductList =productList;
mListener = listener;
}
#NonNull
#Override
public ProductViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
ItemProductBinding binding = DataBindingUtil
.inflate(LayoutInflater.from(parent.getContext()), R.layout.item_product,
parent, false);
return new ProductViewHolder(binding);
}
#Override
public void onBindViewHolder(#NonNull ProductViewHolder holder, int position) {
holder.bind(mProductList.get(position), mListener);
}
#Override
public int getItemCount() {
return mProductList.size();
}
class ProductViewHolder extends RecyclerView.ViewHolder{
final ItemProductBinding binding;
ProductViewHolder(ItemProductBinding binding) {
super(binding.getRoot());
this.binding = binding;
}
void bind(Product currentProduct, ProductItemClickListener clickListener){
//For each item, corresponding product object is passed to the binding
binding.setProduct(currentProduct);
binding.setProductItemClick(clickListener);
//This is to force bindings to execute right away
binding.executePendingBindings();
}
}
public interface ProductItemClickListener {
void onProductItemClicked(Product product);
}
}

How to display multiple objects type in RecyclerView?

I am creating Android app, using room database.
I have two tables DogsTable:
#PrimaryKey(autoGenerate = true)
int dog_id;
String dogName;
and CatsTable (both tables have constructor and getter methods ):
#PrimaryKey(autoGenerate = true)
int cat_id;
String catName;
1- How to display in one RecyclerView two different object type
ArrayList<DogsTable> dog_list;
ArrayList<CatsTable> cat_list;
I am getting the values of dog_list and cat_list from ViewModel Query as show in MainActivity.class.
2- How to fix getItemCount() method? I don't know how to return two different object cat_list.size(); and dog_list.size();
3- Also in onBindViewHolder() method I don`t know how to get cat_list values to display them in UI?
4- Another problem is in swapToDelete() Method in MainActivity.class, I can get the dog id to delete it, but I can not get the cat id to delete it, how can I get the cat id ?
5- How can I display (dog1,dog2 , dog3) as show in first image? (i inserted the value manually in the first image just to show how i want to display them )
Existing Output as below:
My code
MainActivity.java
public class MainActivity extends AppCompatActivity implements MainActivityAdapter.ItemClickListener {
MyViewModel viewModel;
MainActivityAdapter adapter;
RecyclerView recyclerView;
LinearLayoutManager layoutManager;
Button btn_addDog, btn_addCat;
EditText et_addDogName, et_addCatName;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initViews();
viewModel = ViewModelProviders.of(this).get(MyViewModel.class);
actionButton();
buildRecyclerView();
setUpViewModel_dogs();
swapToDelete_dog();
}
private void initViews() {
et_addDogName = findViewById(R.id.addDogNameET_xml);
et_addCatName = findViewById(R.id.addCatNameET_xml);
}
public void actionButton() {
btn_addDog = findViewById(R.id.AddDog_btn_xml);
btn_addCat = findViewById(R.id.AddCat_btn_xml);
btn_addDog.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
insertDog();
}
});
btn_addCat.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
insertCat();
}
});
}
private void buildRecyclerView() {
recyclerView = findViewById(R.id.recyclerView_id);
adapter = new MainActivityAdapter(this, this);
layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);
recyclerView.setAdapter(adapter);
}
// Query
public void setUpViewModel_dogs() {
viewModel = ViewModelProviders.of(this).get(MyViewModel.class);
viewModel.getAllDogs().observe(this, new Observer<List<DogsTable>>() {
#Override
public void onChanged(#Nullable List<DogsTable> dogsTables) {
adapter.setDog_list((ArrayList<DogsTable>) dogsTables);
}
});
}
public void setUpViewModel_cats(){
viewModel.getAllCats().observe(this, new Observer<List<CatsTable>>() {
#Override
public void onChanged(#Nullable List<CatsTable> catsTables) {
adapter.setCat_list((ArrayList<CatsTable>) catsTables);
}
});
}
// Add
public void insertDog() {
String dogName = String.valueOf(et_addDogName.getText()).trim();
DogsTable obj_dog = new DogsTable(dogName);
viewModel.insertDog(obj_dog);
Toast.makeText(this, "Dog Added", Toast.LENGTH_SHORT).show();
}
public void insertCat() {
String catName = String.valueOf(et_addCatName.getText());
CatsTable obj_cat = new CatsTable(catName);
viewModel.insertCat(obj_cat);
Toast.makeText(this, "cat Added", Toast.LENGTH_SHORT).show();
}
// Delete
public void swapToDelete_dog() {
new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {
#Override
public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
return false;
}
#Override
public void onSwiped(final RecyclerView.ViewHolder viewHolder, int direction) {
List<DogsTable> dog_pos = adapter.getDog_list();
viewModel.deleteDog(dog_pos.get(viewHolder.getAdapterPosition()));
}
}
).attachToRecyclerView(recyclerView);
}
public void swapToDelete_cat() {
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu, menu);
return super.onCreateOptionsMenu(menu);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int item_id = item.getItemId();
if (item_id == R.id.menu_add) {
Intent in = new Intent(this, Add.class);
startActivity(in);
}
return super.onOptionsItemSelected(item);
}
#Override
public void onItemClickListener(int pet_id) {
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="vertical"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<EditText
android:id="#+id/addDogNameET_xml"
android:layout_width="250dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginEnd="8dp"
android:hint="add Dog name" />
<Button
android:id="#+id/AddDog_btn_xml"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="add" />
</LinearLayout>
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<EditText
android:id="#+id/addCatNameET_xml"
android:layout_width="250dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginEnd="8dp"
android:hint="add Cat name" />
<Button
android:id="#+id/AddCat_btn_xml"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="add" />
</LinearLayout>
<android.support.v7.widget.RecyclerView
android:id="#+id/recyclerView_id"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:ignore="MissingConstraints" />
</LinearLayout>
MainActivityAdapter.java
public class MainActivityAdapter extends RecyclerView.Adapter<MainActivityAdapter.MyViewHolder> {
Context mContext;
ArrayList<DogsTable> dog_list;
ArrayList<CatsTable> cat_list;
ItemClickListener mItemClickListener;
public MainActivityAdapter(Context context , ItemClickListener itemClickListener) {
this.mContext = context;
this.mItemClickListener = itemClickListener;
}
public interface ItemClickListener {
void onItemClickListener(int pet_id);
}
#NonNull
#Override
public MyViewHolder onCreateViewHolder(#NonNull ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(mContext).inflate(R.layout.activity_main_adapter, viewGroup, false);
return new MyViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull MyViewHolder holder, int position) {
DogsTable dog_pos = dog_list.get(position);
// CatsTable catsTable = cat_list.get(position);
holder.dogName.setText(String.valueOf(dog_pos.getDogName()));
// holder.catName.setText(String.valueOf(catsTable.getCatName()));
}
#Override
public int getItemCount() {
if (dog_list == null ) {
return 0;
} else {
return dog_list.size();
}
}
public class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener , ItemClickListener {
TextView dogName;
TextView catName;
public MyViewHolder(#NonNull View itemView) {
super(itemView);
dogName = itemView.findViewById(R.id.dogName_xml);
catName = itemView.findViewById(R.id.catName_xml);
itemView.setOnClickListener(this);
}
#Override
public void onClick(View view) {
int pet_id = dog_list.get(getAdapterPosition()).getDogs_id();
mItemClickListener.onItemClickListener(pet_id);
}
#Override
public void onItemClickListener(int pet_id) {
int pos = dog_list.get(getAdapterPosition()).getDogs_id();
mItemClickListener.onItemClickListener(pet_id);
}
}
public void setDog_list(ArrayList<DogsTable> dog_list) {
this.dog_list = dog_list;
notifyDataSetChanged();
}
public ArrayList<DogsTable> getDog_list() {
return dog_list;
}
public void setCat_list(ArrayList<CatsTable> cat_list) {
this.cat_list = cat_list;
}
}
activity_main_adapter.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:padding="10dp">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Dogs: " />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="#+id/dogName_xml"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Cats: " />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:padding="10dp">
<TextView
android:id="#+id/catName_xml"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
</LinearLayout>

To support different view types, RecyclerView.Adapter provides a useful method int getItemViewType(int position):
Return the view type of the item at position for the purposes of view recycling.
The default implementation of this method returns 0, making the assumption of a single view type for the adapter. Unlike ListView adapters, types need not be contiguous. Consider using id resources to uniquely identify item view types.
Then, in onCreateViewHolder you can see that a second parameter is int viewType which comes from the method int getItemViewType(int position). Based on that, you can instantiate a ViewHolder you need, e.g. DogViewHolder or CatViewHolder.
But what about storing multiple view models in a single adapter and defining which ViewHolder type should be actually instantiated? Here are two most popular approaches:
Declaring multiple containers for multiple types and defining a custom logic for getItemViewType method, e.g. all odd numbers will go in the dogs' list and even numbers will go in the cats' list (or any other method, but beware that you will have to cope with different lists' sizes and all the view types you need). Also, getItemsCount should be overriden appropriately (return list1.size() + list2.size + ... + listN.size();)
Put all the view models in a single list and perform some kind of attributes checks: either it will be some property or the type itself (not recommended for scalability reasons). Then your code will look like this:
public int getItemViewType(int position) {
CommonParentForUpcasting item = items.get(position);
if (item instanceOf Dog) { // or something like item.type == Animal.CAT
return R.id.holder_dog;
} else {
return R.id.holder_cat;
}
}
If you want to come up with a second solution, this solution should suit you well.
Also, make sure to check this StackOverflow answer.

Set Sticky Header and Items Layouts Recyclerview

I want to build a complex layout using recyclerview android. In the layout, I want to have a camera button to the top left fixed and a recyclerview wrapped around it with gallery images. I have checked flexbox layout manager for recyclerview but it doesn't seem to match my use-case.
I want the header to be non-repeating and not to scroll with other items vertically. Here's the layout for the header:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/shareLayout"
android:layout_width="185dp"
android:layout_height="135dp"
android:layout_below="#id/trendingToolbar"
android:background="#color/black">
<ImageView
android:id="#+id/cameraShareIV"
android:layout_width="60dp"
android:layout_height="60dp"
android:layout_centerHorizontal="true"
android:layout_marginTop="10dp"
app:srcCompat="#drawable/camera_white" />
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#id/cameraShareIV"
android:layout_centerHorizontal="true">
<TextView
android:id="#+id/infoTxt"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_marginLeft="20dp"
android:gravity="center_horizontal"
android:text="#string/share_pic_video"
android:textColor="#android:color/white"
android:textSize="13sp"
android:textStyle="bold" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#id/infoTxt"
android:layout_marginLeft="16dp"
android:text="#string/share_timeout_txt"
android:textColor="#color/colorPrimaryDark"
android:textSize="11sp"
android:textStyle="bold" />
</RelativeLayout>
and in my activity, here's the XML:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="base.android.com.thumbsapp.UI.Fragments.TrendingFragment">
<include layout="#layout/trending_toolbar"
android:id="#+id/trendingToolbar"/>
<android.support.v7.widget.RecyclerView
android:id="#+id/trendingRV"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="#id/trendingToolbar"/>
Previously, I had the header inside the activity XML but had no way to wrap a recyclerview around it. So, I have decide to use an adapter like below:
public class TrendingAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private static final String TAG = TrendingAdapter.class.getSimpleName();
private Context context;
private List<Trending> itemList;
private static final int HEADER = 0;
private static final int ITEMS = 1;
#Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v;
switch (viewType){
case HEADER:
v = LayoutInflater.from(parent.getContext()).inflate(R.layout.trending_header, parent, false);
return new TrendingHeaderViewHolder(v);
case ITEMS:
v = LayoutInflater.from(parent.getContext()).inflate(R.layout.trending_items_layout, parent, false);
return new TrendingItemsViewHolder(v);
}
return null;
}
#Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
Trending tr = itemList.get(position);
if (holder instanceof TrendingHeaderViewHolder){
((TrendingHeaderViewHolder) holder).cameraShareIV.setOnClickListener( view -> {
// TODO: 4/2/2018 select image from gallery
});
} else if (holder instanceof TrendingItemsViewHolder){
// TODO: 4/2/2018 populate gallery items here with picasso
}
}
#Override
public int getItemCount() {
return itemList.size();
}
#Override
public int getItemViewType(int position) {
return super.getItemViewType(position);
}
}
I'm confused how to make the header stick and also what to do for getItemViewType method.
Is this the right way to approach this?
Can anyone help out? Thanks.

For this lay out i suggest better option is use this header view
https://github.com/edubarr/header-decor

To make things simple i suggest you to look into this library
In your XML Place RecylerView into StickyHeaderView,choose horizontal or vertical orientation for your RecylerView
<tellh.com.stickyheaderview_rv.StickyHeaderView
android:id="#+id/stickyHeaderView"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.RecyclerView
android:id="#+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#android:color/white"
android:scrollbars="vertical" />
</tellh.com.stickyheaderview_rv.StickyHeaderView>
Create data bean class for each item type in RecyclerView. They should extend DataBean. Override the method
public boolean shouldSticky() to decide whether the item view should be suspended on the top.
public class User extends DataBean {
private String login;
private int id;
private String avatar_url;
private boolean shouldSticky;
#Override
public int getItemLayoutId(StickyHeaderViewAdapter adapter) {
return R.layout.item_user;
}
public void setShouldSticky(boolean shouldSticky) {
this.shouldSticky = shouldSticky;
}
// Decide whether the item view should be suspended on the top.
#Override
public boolean shouldSticky() {
return shouldSticky;
}
}
public class ItemHeader extends DataBean {
private String prefix;
#Override
public int getItemLayoutId(StickyHeaderViewAdapter adapter) {
return R.layout.header;
}
#Override
public boolean shouldSticky() {
return true;
}
}
Create ViewBinder to bind different type views with specific data beans. As you see, provideViewHolder(View itemView) corresponds for onCreateViewHolder in RecyclerView, and bindView corresponds for onBindViewHolder in RecyclerView.
public class ItemHeaderViewBinder extends ViewBinder<ItemHeader, ItemHeaderViewBinder.ViewHolder> {
#Override
public ViewHolder provideViewHolder(View itemView) {
return new ViewHolder(itemView);
}
#Override
public void bindView(StickyHeaderViewAdapter adapter, ViewHolder holder, int position, ItemHeader entity) {
holder.tvPrefix.setText(entity.getPrefix());
}
#Override
public int getItemLayoutId(StickyHeaderViewAdapter adapter) {
return R.layout.header;
}
static class ViewHolder extends ViewBinder.ViewHolder {
TextView tvPrefix;
public ViewHolder(View rootView) {
super(rootView);
this.tvPrefix = (TextView) rootView.findViewById(R.id.tv_prefix);
}
}
}
Instantiate StickyHeaderViewAdapter for RecyclerView and register ViewBinders for each item types.
rv = (RecyclerView) findViewById(R.id.recyclerView);
rv.setLayoutManager(new LinearLayoutManager(this));
List<DataBean> userList = new ArrayList<>();
adapter = new StickyHeaderViewAdapter(userList)
.RegisterItemType(new UserItemViewBinder())
.RegisterItemType(new ItemHeaderViewBinder());
rv.setAdapter(adapter);

RecyclerView Databinding Item click

I am trying to listen for row clicks (item clicks) on my recycler view from the Activity itself (not from adapter).
My Adapter so far looks like this:
public class ListMiestnostiAdapter extends RecyclerView.Adapter<ListMiestnostiAdapter.ViewHolder>{
private List<Miestnost> data;
// you provide access to all the views for a data item in a view holder
public static class ViewHolder extends RecyclerView.ViewHolder {
public ViewDataBinding binding;
public ViewHolder(ViewDataBinding binding) {
super(binding.getRoot());
this.binding = binding;
}
public void bind(Object obj){
binding.setVariable(BR.obj, obj);
binding.executePendingBindings();
}
}
public ListMiestnostiAdapter(List<Miestnost> data) {
this.data = data;
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
// create a new view
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
ActivityListMiestnostiRowBinding itemBinding = ActivityListMiestnostiRowBinding.inflate(inflater, parent,false);
return new ViewHolder(itemBinding);
}
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
Miestnost item = data.get(position);
holder.bind(item);
}
#Override
public int getItemCount() {
return data.size();
}
}
And my row layout like this:
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:bind="http://schemas.android.com/apk/res-auto">
<data>
<variable
name="obj"
type="com.example.com.projectname.Models.Miestnost" />
</data>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?android:attr/selectableItemBackground"
android:clickable="true"
android:focusable="true"
android:orientation="horizontal"
android:paddingBottom="#dimen/row_padding_vertical"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/row_padding_vertical">
<TextView
android:id="#+id/txt_miestnost_row_nazov"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:text="#{obj.Name}"
android:textSize="16dp" />
</LinearLayout>
</layout>
As I have already mentioned I am trying to listen to item clicks, but not from Adapter itself (as other posts suggested), but from my Activity which holds this RecyclerView.
Is such action even possible? If yes, then any help would be highly appreciated as I could not find anything on google.

You’ll first need an interface that specifies listener’s behavior. In this example, there is a sample model called ContentItem, so the click will return an item of that type:
public interface OnItemClickListener {
void onItemClick(ContentItem item);
}
The constructor will receive an object that implements this interface, along with the items to be rendered:
private final List<ContentItem> items;
private final OnItemClickListener listener;
public ContentAdapter(List<ContentItem> items, OnItemClickListener listener) {
this.items = items;
this.listener = listener;
}
You could alternatively create a setOnItemClickListener method and assign it that way. Now, in onBindViewHolder the ViewHolder will receive the constructor in the custom bind method:
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
holder.bind(items.get(position), listener);
}
This is how this bind method looks:
public void bind(final ContentItem item, final OnItemClickListener listener) {
...
itemView.setOnClickListener(new View.OnClickListener() {
#Override public void onClick(View v) {
listener.onItemClick(item);
}
});
}
Use it whenever you need it by creating a new adapter and the listener that will implement the behavior when an item is clicked. A simple example:
recycler.setAdapter(new ContentAdapter(
items,
new ContentAdapter.OnItemClickListener() {
#Override
public void onItemClick(ContentItem item) {
Toast.makeText(getContext(), "Item Clicked", Toast.LENGTH_LONG).show();
}
}));
Source

To add to the answer provided by João Alvares Neto, we can call the OnItemClickListener directly from the layout.
In the variable tag, we can pass the OnItemClickListener and call it using the android:onClick property.
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
<data>
<variable
name="storyClickListener"
type="com.hoomanwe.zorro.ui.adapter.OnStoryClickListener" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="#{() -> storyClickListener.onStoryClick(item.id)}" />
</layout>
By this way, you can eliminate the following code from the solution provided by João Alvares Neto
public void bind(final ContentItem item, final OnItemClickListener listener) {
itemView.setOnClickListener(new View.OnClickListener() {
#Override public void onClick(View v) {
listener.onItemClick(item);
}
});
}