Develop Reference

Instantiate a generic adapter for RecyclerView

I am a newbie in recyclerview. I have created my generic adapter for different properties by following the #SebastienRieu's answer, i.e. This link. The problem is that I want to instantiate the adapter and set it to my recyclerview. How Do I do that?
Here, 2nd parameter is context. What should replace the 1st paramenter with?
GenericModelAdapter adapter= new GenericModelAdapter(??, this)
recyclerView.setAdapter(adapter);
Any help is appreciated.
My PostModelClass:
public class PostsModelClass {
int userId;
int id;
String title;
#SerializedName("body")
String textBody;
public int getUserId() {
return userId;
}
public int getId() {
return id;
}
public String getTitle() {
return title;
}
public String getTextBody() {
return textBody;
}
}
Similarly, here's my CommentsModelclass:
public class CommentsModelClass {
String postId;
String id;
String name;
String email;
#SerializedName("body")
String textBody;
public String getPostId() {
return postId;
}
public String getId() {
return id;
}
public String getName() {
return name;
}
public String getEmail() {
return email;
}
public String getTextBody() {
return textBody;
}
And here's my adapter:
public class GenericModelAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private Context mContext;
private static final int TYPE_POSTS = 10;
private static final int TYPE_COMMENTS = 11;
private static final int TYPE_PHOTOS = 12;
private static final int TYPE_USERS = 13;
private List<GenericViewModel> mItems;
public GenericModelAdapter(List<GenericViewModel> items, Context context) {
this.mItems = items;
this.mContext = context;
}
#Override
public int getItemViewType(int position) {
GenericViewModel genericItems = mItems.get(position);
if (genericItems.isPostsModel()) {
return TYPE_POSTS;
} else if (genericItems.isCommentsModel()) {
return TYPE_COMMENTS;
} else if (genericItems.isPhotosModel()) {
return TYPE_PHOTOS;
} else {
return TYPE_USERS;
}
}
public static class PostViewHolder extends RecyclerView.ViewHolder {
TextView textViewResult;
PostViewHolder(#NonNull View itemView) {
super(itemView);
textViewResult = itemView.findViewById(R.id.textViewResult);
}
}
public static class CommentsViewHolder extends RecyclerView.ViewHolder {
TextView textViewResult;
CommentsViewHolder(#NonNull View itemView) {
super(itemView);
textViewResult = itemView.findViewById(R.id.textViewResult);
}
}
public static class PhotosViewHolder extends RecyclerView.ViewHolder {
TextView textViewResult;
PhotosViewHolder(#NonNull View itemView) {
super(itemView);
textViewResult = itemView.findViewById(R.id.textViewResult);
}
}
public static class UsersViewHolder extends RecyclerView.ViewHolder {
TextView textViewResult;
UsersViewHolder(#NonNull View itemView) {
super(itemView);
textViewResult = itemView.findViewById(R.id.textViewResult);
}
}
#NonNull
#Override
public RecyclerView.ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(mContext);
if (viewType == TYPE_POSTS) {
View rootView = inflater.inflate(R.layout.single_item, parent, false);
return new PostViewHolder(rootView);
} else if (viewType == TYPE_COMMENTS) {
View rootView = inflater.inflate(R.layout.single_item, parent, false);
return new CommentsViewHolder(rootView);
} else if (viewType == TYPE_PHOTOS) {
View rootView = inflater.inflate(R.layout.single_item, parent, false);
return new PhotosViewHolder(rootView);
} else {
View rootView = inflater.inflate(R.layout.single_item, parent, false);
return new UsersViewHolder(rootView);
}
}
#Override
public void onBindViewHolder(#NonNull RecyclerView.ViewHolder holder, int position) {
GenericViewModel genericViewModel = mItems.get(position);
if (genericViewModel.isPostsModel()) {
onBindPost(holder, genericViewModel.getPostsModelClass());
} else if (genericViewModel.isCommentsModel()) {
//onBindComments(holder, genericViewModel.getCommentsModelClass());
} else if (genericViewModel.isPhotosModel()) {
//onBindPhotos(holder, genericViewModel.getPhotosModelClass());
} else if (genericViewModel.isUsersModel()) {
//onBindUsers(holder, genericViewModel.getUsersModelClass());
}
}
private void onBindPost(RecyclerView.ViewHolder holder, PostsModelClass postsModelClass) {
String content = "User ID: " + postsModelClass.getUserId() +
"\nID: " + postsModelClass.getId() +
"\nTitle: " + postsModelClass.getTitle() +
"\nBody: " + postsModelClass.getTextBody();
((PostViewHolder) holder).textViewResult.setText(content);
}
#Override
public int getItemCount() {
return mItems.size();
}
}
And lastly, My GenericViewModel:
public class GenericViewModel {
private PostsModelClass mPostsModelClass;
private CommentsModelClass mCommentsModelClass;
private PhotosModelClass mPhotosModelClass;
private UsersModelClass mUsersModelClass;
private GenericViewModel(PostsModelClass postsModelClass, CommentsModelClass commentsModelClass, PhotosModelClass photosModelClass, UsersModelClass usersModelClass) {
this.mPostsModelClass = postsModelClass;
this.mCommentsModelClass = commentsModelClass;
this.mPhotosModelClass = photosModelClass;
this.mUsersModelClass = usersModelClass;
}
public boolean isPostsModel() {
return mPostsModelClass != null;
}
public boolean isCommentsModel() {
return mCommentsModelClass != null;
}
public boolean isPhotosModel() {
return mPhotosModelClass != null;
}
public boolean isUsersModel() {
return mUsersModelClass != null;
}
public static GenericViewModel getPostsInstance(PostsModelClass modelClass) {
return new GenericViewModel(modelClass, null, null, null);
}
public static GenericViewModel getCommentsInstance(CommentsModelClass modelClass) {
return new GenericViewModel(null, modelClass, null, null);
}
public static GenericViewModel getPhotosInstance(PhotosModelClass modelClass) {
return new GenericViewModel(null, null, modelClass, null);
}
public static GenericViewModel getUsersInstance(UsersModelClass modelClass) {
return new GenericViewModel(null, null, null, modelClass);
}
public PostsModelClass getPostsModelClass() {
return mPostsModelClass;
}
public CommentsModelClass getCommentsModelClass() {
return mCommentsModelClass;
}
public PhotosModelClass getPhotosModelClass() {
return mPhotosModelClass;
}
public UsersModelClass getUsersModelClass() {
return mUsersModelClass;
}
}
Yes, I haven't shared the model classes for Posts and Users. They are similar to these model classes and I'd implement them later.
Here's the error I'm facing:

Based on the reference you gave in the question, you need a model that contains all your different properties like EventViewModel in the link and populate the list based on the viewType.
ArrayList<EventViewModel> eventList = "YOUR LIST"
GenericModelAdapter adapter= new GenericModelAdapter(eventList, this)

It must be ArrayList of different collected properties:
GenericModelAdapter adapter= new GenericModelAdapter(ArrayList<YourModel> eventList, this)
Your model:
public class YourModel() {
private Property1 mProperty1;
private Property2 mProperty2;
private YourModel(Property1 property1, Property2 property2) {
this.mProperty1 = property1;
this.mProperty2 = property2;
}
public boolean isProperty1() {
return mProperty1 != null
}
public boolean isProperty2() {
return mProperty2 != null
}
public static YourModel getProperty1Instance(Property1 property1) {
return new YourModel(property1, null);
}
public static EventViewModel getProperty2Instance(Property1 property2) {
return new YourModel(null, property2);
}
public Property1 getProperty1() {
return mProperty1;
}
public Property2 getProperty2() {
return mProperty2;
}
}

RecyclerView with different types and different adapter

and thank you for your attention to my request.
I'm a newbie on Andorid Studio and I'm developing an App, it has to show a list of Events, Courses and News. There is a DrawerLayout which allow navigating into Event's, course's and news's area, each area has each specific RecyclerView, but into the home activity, I have to show all the items (Event, Course and News).
I create an Adapter for each item (because they have different properties) and each section (fragment) works properly but now I'm stuck with the main activity (the home).
Here are the models for explaining the difference between them:
Event
public class Event {
private int id;
private String title;
private String description;
private LocalDateTime startingDate;
private LocalDateTime endingDate;
private String cost;
private String website;
private Category category;
private Venue venue;
private Organizer organizer;
private String status;
private int resImage;
public Event(int id, String title, String description, LocalDateTime startingDate, LocalDateTime endingDate, String cost, String website, Category category, Venue venue, Organizer organizer, int image) {
this.id = id;
this.title = title;
this.description = description;
this.startingDate = startingDate;
this.endingDate = endingDate;
this.cost = cost;
this.website = website;
this.category = category;
this.venue = venue;
this.organizer = organizer;
this.resImage = image;
}
public Event(){}
public int getId() {
return id;
}
public String getTitle() {
return title;
}
public void setTitle(String name) {
this.title = title;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public LocalDateTime getStartingDate() {
return startingDate;
}
public void setStartingDate(LocalDateTime startingDate) {
this.startingDate = startingDate;
}
public LocalDateTime getEndingDate() {
return endingDate;
}
public void setEndingDate(LocalDateTime endingDate) {
this.endingDate = endingDate;
}
public String getCost() {
return cost;
}
public void setCost(String cost) {
this.cost = cost;
}
public String getWebsite() {
return website;
}
public void setWebsite(String website) {
this.website = website;
}
public Category getCategory() {
return category;
}
public Venue getVenue() {
return venue;
}
public Organizer getOrganizer() {
return organizer;
}
public String getStatus() {
return status;
}
public int getResImage() {
return resImage;
}
}
News:
public class News {
private int id;
private String title;
private String content;
private int resImage;
public News(int id, String title, String content, int image) {
this.id = id;
this.title = title;
this.content = content;
this.resImage = image;
}
public News(){}
public int getId(){
return this.id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getContent() {
return content;
}
public void setDescription(String description) {
this.content = content;
}
public int getResImage() {
return resImage;
}
public void setResImage(int resImage) {
this.resImage = resImage;
}
}
Courses
public Course(int id, String title, String content, float price, LocalDate startingDate, int availablePlace, Teacher teacher, CourseCategory courseCategory, Location location, Duration duration, Level level, int resImage) {
this.id = id;
this.title = title;
this.content = content;
this.price = price;
this.startingDate = startingDate;
this.availablePlace = availablePlace;
this.teacher = teacher;
this.courseCategory = courseCategory;
this.location = location;
this.duration = duration;
this.level = level;
this.resImage = resImage;
}
public int getId() {
return id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
public float getPrice() {
return price;
}
public void setPrice(float price) {
this.price = price;
}
public LocalDate getStartingDate() {
return startingDate;
}
public void setStartingDate(LocalDate startingDate) {
this.startingDate = startingDate;
}
public int getAvailablePlace() {
return availablePlace;
}
public void setAvailablePlace(int availablePlace) {
this.availablePlace = availablePlace;
}
public Teacher getTeacher() {
return teacher;
}
public void setTeacher(Teacher teacher) {
this.teacher = teacher;
}
public CourseCategory getCourseCategory() {
return courseCategory;
}
public void setCourseCategory(CourseCategory courseCategory) {
this.courseCategory = courseCategory;
}
public Location getLocation() {
return location;
}
public void setLocation(Location location) {
this.location = location;
}
public Duration getDuration() {
return duration;
}
public void setDuration(Duration duration) {
this.duration = duration;
}
public Level getLevel() {
return level;
}
public int getResImage() {
return resImage;
}
public void setResImage(int resImage) {
this.resImage = resImage;
}
}
Here is the Adapters:
EventAdapter
public class EventViewAdapter extends RecyclerView.Adapter<EventViewAdapter.EventViewHolder> {
ArrayList<Event> eventList;
Context context;
public EventViewAdapter(ArrayList<Event> eventList, Context context) {
this.eventList = eventList;
this.context = context;
}
public EventViewAdapter() {
}
public static class EventViewHolder extends RecyclerView.ViewHolder {
ImageView eventImage;
TextView startingDate, place, title;
LinearLayout cellLayout;
EventViewHolder(View eventView) {
super(eventView);
eventImage = eventView.findViewById(R.id.event_image);
startingDate = eventView.findViewById(R.id.event_starting_date);
place = eventView.findViewById(R.id.event_place);
title = eventView.findViewById(R.id.event_title);
cellLayout = eventView.findViewById(R.id.event_cell_layout);
}
}
#NonNull
#Override
public EventViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.event_cell_def, parent, false);
EventViewHolder evh = new EventViewHolder(view);
return evh;
}
#Override
public void onBindViewHolder(#NonNull EventViewHolder holder, int position) {
final String title = eventList.get(position).getTitle();
final String description = eventList.get(position).getDescription();
final String place = eventList.get(position).getVenue().getCity();
final String address = eventList.get(position).getVenue().getAddress();
final String startDate = String.valueOf(eventList.get(position).getStartingDate().toLocalDate());
final String startTime = String.valueOf(eventList.get(position).getStartingDate().getHour() + ":" + String.valueOf(eventList.get(position).getStartingDate().getMinute()));
final String endDate = String.valueOf(eventList.get(position).getEndingDate().toLocalDate());
final String cost = eventList.get(position).getCost();
final String website = eventList.get(position).getWebsite();
final String category = eventList.get(position).getCategory().getName();
final String organizer = eventList.get(position).getOrganizer().getOrganizer();
final String organizerWebsite = eventList.get(position).getOrganizer().getWebsite();
final int image = eventList.get(position).getResImage();
holder.eventImage.setImageResource(image);
holder.startingDate.setText(startDate);
holder.place.setText(place);
holder.title.setText(title);
holder.cellLayout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(v.getContext(), DetailEventActivity.class);
intent.putExtra("title", title);
intent.putExtra("description", description);
intent.putExtra("place", place);
intent.putExtra("address", address);
intent.putExtra("startDate", startDate);
intent.putExtra("startTime", startTime);
intent.putExtra("endDate", endDate);
intent.putExtra("cost", cost);
intent.putExtra("website", website);
intent.putExtra("category", category);
intent.putExtra("organizer", organizer);
intent.putExtra("orgWebsite", organizerWebsite);
intent.putExtra("image", image);
v.getContext().startActivity(intent);
Toast.makeText(context, "Hai premuto su: " + title, Toast.LENGTH_SHORT).show();
}
});
}
#Override
public int getItemCount() {
return eventList.size();
}
public void eventSetSearchOperation(ArrayList<Event> newList){
eventList = new ArrayList<>();
eventList.addAll(newList);
notifyDataSetChanged();
}
}
CourseAdapter:
public class CourseViewAdapter extends RecyclerView.Adapter<CourseViewAdapter.CourseViewHolder> {
ArrayList<Course> courseList;
Context context;
public CourseViewAdapter(ArrayList<Course> courseList, Context context) {
this.courseList = courseList;
this.context = context;
}
public CourseViewAdapter(){}
public static class CourseViewHolder extends RecyclerView.ViewHolder {
ImageView courseImage;
TextView startingDate, place, title;
LinearLayout courseLinear;
CourseViewHolder(View courseView){
super(courseView);
courseImage = courseView.findViewById(R.id.course_image);
startingDate = courseView.findViewById(R.id.course_starting_date);
place = courseView.findViewById(R.id.course_place);
title = courseView.findViewById(R.id.course_title);
courseLinear = courseView.findViewById(R.id.course_cell_layout);
}
}
#NonNull
#Override
public CourseViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.course_cell_def, parent, false);
CourseViewHolder cvh = new CourseViewHolder(view);
return cvh;
}
#Override
public void onBindViewHolder(#NonNull CourseViewHolder holder, int position) {
final String title = courseList.get(position).getTitle();
final String category = courseList.get(position).getCourseCategory().getName();
final String description = courseList.get(position).getContent();
final String place = courseList.get(position).getLocation().getName();
final String startDate = String.valueOf(courseList.get(position).getStartingDate());
final int availablePlace = courseList.get(position).getAvailablePlace();
final String teacher = courseList.get(position).getTeacher().getName();
final String teacherEmail = courseList.get(position).getTeacher().getEmail();
final String teacherMobile = courseList.get(position).getTeacher().getPhone();
final String duration = courseList.get(position).getDuration().getName();
final String level = courseList.get(position).getLevel().getName();
final String price = String.valueOf(courseList.get(position).getPrice());
final int image = courseList.get(position).getResImage();
holder.courseImage.setImageResource(image);
holder.startingDate.setText(startDate);
holder.place.setText(place);
holder.title.setText(title);
holder.courseLinear.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(v.getContext(), DetailCourseActivity.class);
intent.putExtra("title", title);
intent.putExtra("category", category);
intent.putExtra("content", description);
intent.putExtra("startDate", startDate);
intent.putExtra("availablePlace", availablePlace);
intent.putExtra("teacher", teacher);
intent.putExtra("teacherEmail", teacherEmail);
intent.putExtra("teacherMobile", teacherMobile);
intent.putExtra("duration", duration);
intent.putExtra("price", price);
intent.putExtra("place", place);
intent.putExtra("level", level);
intent.putExtra("image", image);
v.getContext().startActivity(intent);
Toast.makeText(context, "Hai premuto su: " + title, Toast.LENGTH_SHORT).show();
}
});
}
#Override
public int getItemCount() {
return courseList.size();
}
public void courseSetSearchOperation(ArrayList<Course> newList){
courseList = new ArrayList<>();
courseList.addAll(newList);
notifyDataSetChanged();
}
}
News:
public class NewsViewAdapter extends RecyclerView.Adapter<NewsViewAdapter.NewsViewHolder> {
ArrayList<News> newsList;
Context context;
public NewsViewAdapter(ArrayList<News> newsList, Context context) {
this.newsList = newsList;
this.context = context;
}
public NewsViewAdapter(){}
public static class NewsViewHolder extends RecyclerView.ViewHolder {
ImageView newsImage;
TextView newsTitle, newsContent;
LinearLayout newsLayout;
NewsViewHolder(View newView){
super(newView);
newsImage = newView.findViewById(R.id.news_image);
newsTitle = newView.findViewById(R.id.news_title);
newsContent = newView.findViewById(R.id.news_content);
newsLayout = newView.findViewById(R.id.news_cell_layout);
}
}
#NonNull
#Override
public NewsViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.news_cell_def, parent, false);
NewsViewHolder nvh = new NewsViewHolder(view);
return nvh;
}
#Override
public void onBindViewHolder(#NonNull NewsViewHolder holder, int position) {
final String title = newsList.get(position).getTitle();
final String content = newsList.get(position).getContent();
final int image = newsList.get(position).getResImage();
holder.newsImage.setImageResource(image);
holder.newsTitle.setText(title);
holder.newsContent.setText(content);
holder.newsLayout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(v.getContext(), DetailNewsActivity.class);
intent.putExtra("title", title);
intent.putExtra("content", content);
intent.putExtra("image", image);
v.getContext().startActivity(intent);
Toast.makeText(context, "Premuto su: " + title, Toast.LENGTH_SHORT).show();
}
});
}
#Override
public int getItemCount() {
return newsList.size();
}
public void newsSetSearchOperation(ArrayList<News> newList){
newsList = new ArrayList<>();
newsList.addAll(newList);
notifyDataSetChanged();
}
}
Each specific list of item is into a fragment, indeed here is the Main Activity (home), where I would like to display a RecyclerView of all the itmes:
public class MainActivity extends AppCompatActivity {
private DrawerLayout drawerLayout;
private NavigationView mNavigationView;
private Toolbar toolbar;
private ActionBarDrawerToggle drawerToggle;
private FloatingActionButton fab;
private RecyclerView mRecyclerView;
private ImageView openFilter;
private SearchView searchView;
private DataMock dataMock = new DataMock();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mRecyclerView = findViewById(R.id.recycler_view_main);
drawerLayout = findViewById(R.id.drawer_layout);
mNavigationView = findViewById(R.id.nav_view);
toolbar = findViewById(R.id.toolbar);
openFilter = findViewById(R.id.filter_icon);
searchView = findViewById(R.id.action_search);
fab = findViewById(R.id.fab);
fab.show();
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
searchView.setQueryHint(getString(R.string.search_hint));
drawerToggle = setupDrawerToggle();
drawerToggle.setDrawerIndicatorEnabled(true);
drawerToggle.syncState();
drawerLayout.setDrawerListener(drawerToggle);
drawerLayout.setDrawerListener(new DrawerLayout.SimpleDrawerListener() {
#Override
public void onDrawerOpened(View drawerView) {
super.onDrawerOpened(drawerView);
}
#Override
public void onDrawerClosed(View drawerView) {
super.onDrawerClosed(drawerView);
}
});
mNavigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem menuItem) {
Fragment nextFragment;
switch (menuItem.getItemId()){
case R.id.event_list:
nextFragment = new EventFragment();
break;
case R.id.course_list:
nextFragment = new CourseFragment();
break;
case R.id.news_list:
nextFragment = new NewsFragment();
break;
default:
throw new IllegalArgumentException("No Fragment for the given menu item");
}
if (nextFragment != null){
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.anchor_point, nextFragment)
.commit();
menuItem.setChecked(true);
setTitle(menuItem.getTitle());
drawerLayout.closeDrawer(mNavigationView);
}
return false;
}
});
openFilter.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
BottomSheetDialog filterDialog = new BottomSheetDialog();
filterDialog.show(getSupportFragmentManager(), "filter dialog opened!");
}
});
// mRecyclerView.setHasFixedSize(true);
// LinearLayoutManager layoutManager = new LinearLayoutManager(this);
// mRecyclerView.setLayoutManager(layoutManager);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// The action bar home/up action should open or close the drawer.
switch (item.getItemId()) {
case android.R.id.home:
drawerLayout.openDrawer(GravityCompat.START);
return true;
}
return super.onOptionsItemSelected(item);
}
private ActionBarDrawerToggle setupDrawerToggle() {
// NOTE: Make sure you pass in a valid toolbar reference. ActionBarDrawToggle() does not require it
// and will not render the hamburger icon without it.
return new ActionBarDrawerToggle(this, drawerLayout, toolbar, R.string.drawer_open, R.string.drawer_close);
}
public void backToHome(View view){
for (Fragment fragment : getSupportFragmentManager().getFragments()){
if (fragment != null && (fragment instanceof CourseFragment || fragment instanceof EventFragment || fragment instanceof NewsFragment)){
getSupportFragmentManager().beginTransaction().remove(fragment).commit();
toolbar.setTitle("WePress");
fab.show();
}
}
Toast.makeText(this, "Premuto sul logo", Toast.LENGTH_SHORT).show();
drawerLayout.closeDrawer(mNavigationView);
}
#Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
// Sync the toggle state after onRestoreInstanceState has occurred.
drawerToggle.syncState();
}
#Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Pass any configuration change to the drawer toggles
drawerToggle.onConfigurationChanged(newConfig);
}
public void addItem(View view){
PopupMenu popupMenu = new PopupMenu(MainActivity.this, fab);
popupMenu.getMenuInflater().inflate(R.menu.fab_main_menu, popupMenu.getMenu());
popupMenu.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
#Override
public boolean onMenuItemClick(MenuItem item) {
switch (item.getItemId()){
case R.id.add_event:
Toast.makeText(MainActivity.this, "Pronti per aggiungere un evento", Toast.LENGTH_SHORT).show();
Intent intentEvent = new Intent(MainActivity.this, AddItemActivity.class);
intentEvent.putExtra("isFrom", "event");
startActivity(intentEvent);
break;
case R.id.add_course:
Toast.makeText(MainActivity.this, "Pronti per aggiungere un corso", Toast.LENGTH_SHORT).show();
Intent intentCourse = new Intent(MainActivity.this, AddItemActivity.class);
intentCourse.putExtra("isFrom", "course");
startActivity(intentCourse);
break;
case R.id.add_news:
Toast.makeText(MainActivity.this, "Pronti per aggiungere una news", Toast.LENGTH_SHORT).show();
Intent intentNews = new Intent(MainActivity.this, AddItemActivity.class);
intentNews.putExtra("isFrom", "news");
startActivity(intentNews);
break;
}
return true;
}
});
popupMenu.show();
}
}
if it's possible to show the list with differents layouts, can you also suggest a way to improve the quality of my code avoiding to repeat lines of code? If I'm not wrong, I would like to re-use each Adapter or part of them that I can put into a specific class (?).
Thank you so much for your help!
If I'm missing some information, please ask me in order to edit the post.

You must do only one adapter (using view type) with a view model class
that contain either an event or a news or a course
the adapter should be something like that:
public class EventViewAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private static final int TYPE_EVENT = 10;
private static final int TYPE_COURSE = 11;
private static final int TYPE_NEWS = 12;
ArrayList<EventViewModel> eventList;
Context context;
public EventViewAdapter(ArrayList<EventViewModel> eventList, Context context) {
this.eventList = eventList;
this.context = context;
}
public EventViewAdapter() {
}
#Override
public int getItemViewType(int position) {
EventViewModel event = eventList.get(position);
if (event.isEvent()) {
return TYPE_EVENT ;
} else if(event.isCourse()) {
return TYPE_COURSE;
} else {
return TYPE_NEWS;
}
}
public static class EventViewHolder extends RecyclerView.ViewHolder {
ImageView eventImage;
//....
EventViewHolder(View eventView) {
super(eventView);
eventImage = eventView.findViewById(R.id.event_image);
//.....
}
}
public static class CourseViewHolder extends RecyclerView.ViewHolder {
ImageView courseImage;
//.....
CourseViewHolder(View courseView) {
super(courseView);
courseImage = courseView.findViewById(R.id.course_image);
//.....
}
public static class NewsViewHolder extends RecyclerView.ViewHolder {
ImageView newsImage;
//.....
NewsViewHolder(View newView){
super(newView);
newsImage = newView.findViewById(R.id.news_image);
//.....
}
#NonNull
#Override
public RecyclerView.ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
if (viewType == TYPE_EVENT) {
View rootView = LayoutInflater.from(parent.getContext()).inflate(R.layout.event_cell_def, parent, false);
return new EventViewHolder (rootView);
} else if (viewType == TYPE_COURSE) {
View rootView = LayoutInflater.from(parent.getContext()).inflate(R.layout.course_cell_def, parent, false);
return new CourseViewHolder(rootView);
} else {
View rootView = LayoutInflater.from(parent.getContext()).inflate(R.layout.news_cell_def, parent, false);
return new NewsViewHolder(rootView);
}
}
#Override
public void onBindViewHolder(#NonNull EventViewHolder holder, int position)
{
final EventViewModel eventViewModel = eventList.get(position);
if (eventViewModel .isEvent()) {
onBindEvent(holder, eventViewModel.getEvent());
} else if(eventViewModel .isCourse()) {
onBindCourse(holder, eventViewModel.getCourse());
} else {
onBindNews(holder, eventViewModel.getNews());
}
}
private void onBindEvent(RecyclerView.ViewHolder holder, Event event) {
EventViewHolder eventHolder= (EventViewHolder ) holder;
final String title = event.getTitle();
final String description = event.getDescription();
// others ...
holder.eventImage.setImageResource(image);
holder.startingDate.setText(startDate);
// others ...
holder.cellLayout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
}
});
// ...
}
#Override
public int getItemCount() {
return eventList.size();
}
public void eventSetSearchOperation(ArrayList<Event> newList){
eventList = new ArrayList<>();
eventList.addAll(newList);
notifyDataSetChanged();
}
}
And a View Model classes like that :
public class EventViewModel() {
private Event mEvent;
private Course mCourse;
private News mNews;
private EventViewModel(Event event, Course course, News news) {
this.mEvent = event;
this.mCourse = course;
this.mNews = news;
}
public boolean isEvent() {
return mEvent != null
}
public boolean isCourse() {
return mCourse != null
}
public boolean isNews() {
return mNews != null
}
public static EventViewModel getEventInstance(Event event) {
return new EventViewModel(event, null, null
}
public static EventViewModel getCourseInstance(Course course) {
return new EventViewModel(null, course, null
}
public static EventViewModel getNewsInstance(News news) {
return new EventViewModel(null, null, news
}
public Event getEvent() {
return mEvent;
}
public Event getCourse() {
return mScore;
}
public Event getNews() {
return mNews;
}
}
You can use this adapter in all of your fragments (event, course, news) and each fragment contaions a list of EventViewModel with only its specific type. The adapter display in the main activity contains EventViewModel of all types to display all events.

Chat RecyclerView is blank, Showing nothing but Data is being fetched

I am trying to show Recyclerview in chat form, but it is blank can't find the issue here is the code, I don't know where the issue is but it might be in adapter.
MessageListAdapter.java
public class MessageListAdapter extends RecyclerView.Adapter {
private static final int VIEW_TYPE_MESSAGE_SENT = 1;
private static final int VIEW_TYPE_MESSAGE_RECEIVED = 2;
private Context mContext;
private List<ItemMessage> mMessageList;
public MessageListAdapter(Context context, List<ItemMessage> messageList) {
mContext = context;
mMessageList = messageList;
}
#Override
public int getItemCount() {
return mMessageList.size();
}
// Determines the appropriate ViewType according to the sender of the message.
#Override
public int getItemViewType(int position) {
ItemMessage message = mMessageList.get(position);
if (message.getSender().equals(FirebaseAuth.getInstance().getCurrentUser().getUid())) {
// If the current user is the sender of the message
return VIEW_TYPE_MESSAGE_SENT;
} else {
// If some other user sent the message
return VIEW_TYPE_MESSAGE_RECEIVED;
}
}
// Inflates the appropriate layout according to the ViewType.
#Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view;
if (viewType == VIEW_TYPE_MESSAGE_SENT) {
view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.item_message_sent, parent, false);
return new SentMessageHolder(view);
} else if (viewType == VIEW_TYPE_MESSAGE_RECEIVED) {
view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.item_message_received, parent, false);
return new ReceivedMessageHolder(view);
}
return null;
}
// Passes the message object to a ViewHolder so that the contents can be bound to UI.
#Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
ItemMessage message = mMessageList.get(position);
switch (holder.getItemViewType()) {
case VIEW_TYPE_MESSAGE_SENT:
((SentMessageHolder) holder).bind(message);
break;
case VIEW_TYPE_MESSAGE_RECEIVED:
((ReceivedMessageHolder) holder).bind(message);
}
}
private class SentMessageHolder extends RecyclerView.ViewHolder {
TextView messageText, timeText;
SentMessageHolder(View itemView) {
super(itemView);
messageText = (TextView) itemView.findViewById(R.id.text_message_body);
timeText = (TextView) itemView.findViewById(R.id.text_message_time);
}
void bind(ItemMessage message) {
messageText.setText(message.getMessgae());
// Format the stored timestamp into a readable String using method.
timeText.setText(message.getTime());
}
}
private class ReceivedMessageHolder extends RecyclerView.ViewHolder {
TextView messageText, timeText, nameText;
ImageView profileImage;
ReceivedMessageHolder(View itemView) {
super(itemView);
messageText = (TextView) itemView.findViewById(R.id.text_message_body);
timeText = (TextView) itemView.findViewById(R.id.text_message_time);
nameText = (TextView) itemView.findViewById(R.id.text_message_name);
profileImage = (ImageView) itemView.findViewById(R.id.image_message_profile);
}
void bind(ItemMessage message) {
messageText.setText(message.getMessgae());
// Format the stored timestamp into a readable String using method.
timeText.setText(message.getTime());
nameText.setText("kdkdk");
// Insert the profile image from the URL into the ImageView.
// Utils.displayRoundImageFromUrl(mContext, message.getSender().getProfileUrl(), profileImage);
}
}
}
ItemMessage.java
public class ItemMessage {
private String sender = null;
private String reciever = null;
private String time = null;
private String messgae = null;
public ItemMessage() {
}
public ItemMessage(String sender, String reciever, String time, String messgae) {
this.sender = sender;
this.reciever = reciever;
this.time = time;
this.messgae = messgae;
}
public String getSender() {
return sender;
}
public void setSender(String sender) {
this.sender = sender;
}
public String getReciever() {
return reciever;
}
public void setReciever(String reciever) {
this.reciever = reciever;
}
public String getTime() {
return time;
}
public void setTime(String time) {
this.time = time;
}
public String getMessgae() {
return messgae;
}
public void setMessgae(String messgae) {
this.messgae = messgae;
}
}
fetching code.
childEventListener = new ChildEventListener() {
#Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
ItemMessage itemMessage = dataSnapshot.getValue(ItemMessage.class);
friendlyMessages.add(itemMessage);
mMessageAdapter.notifyDataSetChanged();
Log.d("SSSSz" , friendlyMessages.size()+"");
Log.d("SSSSz", itemMessage.getMessgae());
}
#Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
}
#Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
#Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
};
databaseReferencemsg.addChildEventListener(childEventListener);
I am not posting rest of the code because I know issue is here.

thoughtbot recyclerview expandable groups not expdaning

im using thoughtbot expandable recyclerview (https://github.com/thoughtbot/expandable-recycler-view) and i can't get to expand groups on clicks. also i know that the child items are not even binded (not sure if they were supposed to bind or only on expanding of group.)
my view holders:
public class PlaylistViewHolder extends GroupViewHolder {
private TextView mPlaylistName, mPlaylistCount;
private ImageView arrow;
ExpandableListView.OnGroupClickListener listener;
public PlaylistViewHolder(View itemView) {
super(itemView);
mPlaylistName = itemView.findViewById(R.id.playlistNameView);
mPlaylistCount = itemView.findViewById(R.id.videosCount);
arrow = itemView.findViewById(R.id.expandBtn);
}
public void setCurrentPlaylist(YoutubePlaylist playlist){
Log.e("###",playlist.toString());
mPlaylistName.setText(playlist.getListTitle());
mPlaylistCount.setText("5");
}
}
/////
public class VideoViewHolder extends ChildViewHolder {
TextView mVideoName,mVideoLinkView;
ImageView mVideoThumb;
public VideoViewHolder(View itemView) {
super(itemView);
mVideoName = itemView.findViewById(R.id.videoNameView);
mVideoThumb = itemView.findViewById(R.id.videoThumb);
mVideoLinkView = itemView.findViewById(R.id.videoLinkView);
}
public void onBind(YoutubeVideo video){
Log.e("###","Video binded!!!!!!!");
mVideoName.setText(video.getTitle());
mVideoLinkView.setText(video.getThumbnailLink());
}
}
my classes:
the group class:
public class YoutubePlaylist extends ExpandableGroup<YoutubeVideo> {
#SerializedName("ListTitle")
private String title;
#SerializedName("ListItems")
private ArrayList<YoutubeVideo> videos;
public YoutubePlaylist(String title, List<YoutubeVideo> items) {
super(title, items);
this.title = title;
}
public String getListTitle() {
return title;
}
public void setListTitle(String listTitle) {
this.title = listTitle;
}
public ArrayList<YoutubeVideo> getVideos() {
return videos;
}
public void setVideos(ArrayList<YoutubeVideo> videos) {
this.videos = videos;
}
#Override
public String toString() {
return "YoutubePlaylist{" +
"title='" + title + '\'' +
", videos=" + videos +
'}';
}
}
my child class:
class YoutubeVideo implements Parcelable {
#SerializedName("Title")
private String title;
#SerializedName("link")
private String linkToVideo;
#SerializedName("thumb")
private String thumbnailLink;
public YoutubeVideo(String title, String linkToVideo, String thumbnailLink) {
this.title = title;
this.linkToVideo = linkToVideo;
this.thumbnailLink = thumbnailLink;
}
protected YoutubeVideo(Parcel in) {
title = in.readString();
linkToVideo = in.readString();
thumbnailLink = in.readString();
}
public static final Creator<YoutubeVideo> CREATOR = new Creator<YoutubeVideo>() {
#Override
public YoutubeVideo createFromParcel(Parcel in) {
return new YoutubeVideo(in);
}
#Override
public YoutubeVideo[] newArray(int size) {
return new YoutubeVideo[size];
}
};
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getLinkToVideo() {
String newLink;
if (linkToVideo.contains(" ")) {
newLink = linkToVideo.replaceAll(" ", "");
return newLink;
}
return linkToVideo;
}
public void setLinkToVideo(String linkToVideo) {
this.linkToVideo = linkToVideo;
}
public String getThumbnailLink() {
String fixedThumb=thumbnailLink;
if (thumbnailLink.contains(" ")) {
fixedThumb = thumbnailLink.replaceAll(" ", "");
return fixedThumb;
}
return thumbnailLink;
}
public void setThumbnailLink(String thumbnailLink) {
this.thumbnailLink = thumbnailLink;
}
#Override
public String toString() {
return "YoutubeVideo{" +
"title='" + getTitle() + '\'' +
", linkToVideo='" + getLinkToVideo() + '\'' +
", thumbnailLink='" + getThumbnailLink() + '\'' +
'}';
}
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(title);
dest.writeString(linkToVideo);
dest.writeString(thumbnailLink);
}
}
the adapter:
public class PlaylistAdapter extends
ExpandableRecyclerViewAdapter<PlaylistViewHolder, VideoViewHolder> {
public PlaylistAdapter(List<? extends ExpandableGroup> groups) {
super(groups);
}
#Override
public PlaylistViewHolder onCreateGroupViewHolder(ViewGroup parent, int
viewType) {
View view =
LayoutInflater.from(parent.getContext()).inflate(R.layout.playlist_item,
parent, false);
return new PlaylistViewHolder(view);
}
#Override
public VideoViewHolder onCreateChildViewHolder(ViewGroup parent, int
viewType) {
View view =
LayoutInflater.from(parent.getContext()).inflate(R.layout.video_item,
parent,
false);
return new VideoViewHolder(view);
}
#Override
public void onBindChildViewHolder(VideoViewHolder holder, int flatPosition,
ExpandableGroup group, int childIndex) {
YoutubeVideo video = (YoutubeVideo) group.getItems().get(childIndex);
holder.onBind(video);
}
#Override
public void onBindGroupViewHolder(PlaylistViewHolder holder, int
flatPosition, ExpandableGroup group) {
holder.setCurrentPlaylist((YoutubePlaylist) group);
}
}
main activity:
public class MainActivity extends AppCompatActivity {
RecyclerView videoListView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
GetJsonFromUrl getJsonService = RetrofitInstance.getRetrofitInstance().create(GetJsonFromUrl.class);
Call<JsonObject> call = getJsonService.getJSON();
call.enqueue(new Callback<JsonObject>() {
#Override
public void onResponse(Call<JsonObject> call, Response<JsonObject> response) {
if(response.isSuccessful()){
JsonArray array = response.body().getAsJsonArray("Playlists");
Gson gson = new Gson();
Type type = new TypeToken<ArrayList<YoutubePlaylist>>(){}.getType();
ArrayList<YoutubePlaylist> youtubePlay = gson.fromJson(array, type);
for(YoutubePlaylist playlist : youtubePlay){
ArrayList<YoutubeVideo> videos = playlist.getVideos();
Log.e("###",videos.toString());
}
setArrayToAdapter(youtubePlay);
}
}
#Override
public void onFailure(Call<JsonObject> call, Throwable t) {
}
});
}
private void setArrayToAdapter(ArrayList<YoutubePlaylist> youtubePlay) {
videoListView = findViewById(R.id.videosView);
LinearLayoutManager manager = new LinearLayoutManager(this);
PlaylistAdapter adapter = new PlaylistAdapter(youtubePlay);
videoListView.setLayoutManager(manager);
videoListView.setAdapter(adapter);
}
}
playlist object output example:
YoutubePlaylist{title='Zen Work Music', videos=[YoutubeVideo{title='HEALING ZEN Music', linkToVideo='https://www.youtube.com/watch?v=SbCpzWMWb68', thumbnailLink='https://i.ytimg.com/vi_webp/SbCpzWMWb68/mqdefault.webp'}, YoutubeVideo{title='Relaxing Music - Meditation', linkToVideo='https://www.youtube.com/watch?v=qrx1vyvtRLY', thumbnailLink='https://i.ytimg.com/vi_webp/qrx1vyvtRLY/mqdefault.webp'}, YoutubeVideo{title='Relaxing Music - Background', linkToVideo='https://www.youtube.com/watch?v=loIZy6GqhUw', thumbnailLink='https://i.ytimg.com/vi_webp/loIZy6GqhUw/mqdefault.webp'}, YoutubeVideo{title='Delta Waves Sleep Music', linkToVideo='https://www.youtube.com/watch?v=EshmcHB3yMg', thumbnailLink='https://i.ytimg.com/vi_webp/EshmcHB3yMg/mqdefault.webp'}]}
im getting the groups binded and shown on list, but nothing happens onClick and i did'nt see anything regarding onClickListener in the documentation.
Thanks in advance!

The issue with this is that from the documentation here you don't have to pass your custom model YoutubePlaylist.java as a parameter as you did rather you replace it with ExpandableGroup so for your code
public class PlaylistViewHolder extends GroupViewHolder {
private TextView mPlaylistName, mPlaylistCount;
private ImageView arrow;
ExpandableListView.OnGroupClickListener listener;
public PlaylistViewHolder(View itemView) {
super(itemView);
mPlaylistName = itemView.findViewById(R.id.playlistNameView);
mPlaylistCount = itemView.findViewById(R.id.videosCount);
arrow = itemView.findViewById(R.id.expandBtn);
}
public void setCurrentPlaylist(ExpandableGroup playlist){
//the parameter has to be ExpandableGroup class and you can only get title
Log.e("###",playlist.getTitle());//you must call the getTitle() method
mPlaylistName.setText(playlist.getListTitle());
mPlaylistCount.setText("5");
}
}
This could be the way it was built. maybe a workaround this may be for
this method to then accept two parameters which is the ExpandableGroup
class and the custom model, class
public void setCurrentPlaylist(ExpandableGroup playlist, YoutubePlaylist playlist2){
//the parameter has to be ExpandableGroup class and you can only get title
Log.e("###",playlist.getTitle());//you must call the getTitle() method
mPlaylistName.setText(playlist2.getListTitle());
mPlaylistCount.setText("5");
}

How to show date in between conversation in recyclerview or in listview

How to show date or today , yesterday like text in between conversation
like whatsapp

MainActivity
public class MainActivity extends AppCompatActivity {
private ChatAdapter chatAdapter;
private RecyclerView recyclerView;
private Context context;
private int loggedInUserID;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
bindRecyclerView();
// TODO get logged in user id and initialize into 'loggedInUserID'
}
#Override
protected void onResume() {
super.onResume();
getData();
}
private void getData() {
/**
*Your server call to get data and parse json to your appropriate model
* after parsing json to model simply call the
*/
List<ChatModel> chatModelList = ParseData.chatParser(jsonArray);
groupDataIntoHashMap(chatModelList);
}
private void bindRecyclerView() {
chatAdapter = new ChatAdapter(null);
chatAdapter.setUser(loggedInUserID);
RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(context);
recyclerView.setLayoutManager(mLayoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setAdapter(chatAdapter);
}
private void groupDataIntoHashMap(List<ChatModel> chatModelList) {
LinkedHashMap<String, Set<ChatModel>> groupedHashMap = new LinkedHashMap<>();
Set<ChatModel> list = null;
for (ChatModel chatModel : chatModelList) {
//Log.d(TAG, travelActivityDTO.toString());
String hashMapKey = DateParser.convertDateToString(chatModel.getChatTime());
//Log.d(TAG, "start date: " + DateParser.convertDateToString(travelActivityDTO.getStartDate()));
if (groupedHashMap.containsKey(hashMapKey)) {
// The key is already in the HashMap; add the pojo object
// against the existing key.
groupedHashMap.get(hashMapKey).add(chatModel);
} else {
// The key is not there in the HashMap; create a new key-value pair
list = new LinkedHashSet<>();
list.add(chatModel);
groupedHashMap.put(hashMapKey, list);
}
}
//Generate list from map
generateListFromMap(groupedHashMap);
}
private List<ListObject> generateListFromMap(LinkedHashMap<String, Set<ChatModel>> groupedHashMap) {
// We linearly add every item into the consolidatedList.
List<ListObject> consolidatedList = new ArrayList<>();
for (String date : groupedHashMap.keySet()) {
DateObject dateItem = new DateObject();
dateItem.setDate(date);
consolidatedList.add(dateItem);
for (ChatModel chatModel : groupedHashMap.get(date)) {
ChatModelObject generalItem = new ChatModelObject();
generalItem.setChatModel(chatModel);
consolidatedList.add(generalItem);
}
}
chatAdapter.setDataChange(consolidatedList);
return consolidatedList;
}
}
ChatModel.java
public class ChatModel implements Serializable {
private String messageId;
private int userId;
private String firstName;
private String userName;
private String message;
private Date chatTime;
//TODO generate getter and setter
}
ListObject.java (to determind the type of message)
public abstract class ListObject {
public static final int TYPE_DATE = 0;
public static final int TYPE_GENERAL_RIGHT = 1;
public static final int TYPE_GENERAL_LEFT = 2;
abstract public int getType(int userId);
}
DateObject.java
public class DateObject extends ListObject {
private String date;
public String getDate() {
return date;
}
public void setDate(String date) {
this.date = date;
}
#Override
public int getType(int userId) {
return TYPE_DATE;
}
}
ChatModelObject.java
public class ChatModelObject extends ListObject {
private ChatModel chatModel;
public ChatModel getChatModel() {
return chatModel;
}
public void setChatModel(ChatModel chatModel) {
this.chatModel = chatModel;
}
#Override
public int getType(int userId) {
if (this.chatModel.getUserId() == userId) {
return TYPE_GENERAL_RIGHT;
} else
return TYPE_GENERAL_LEFT;
}
}
DateParse.java to parse date for grouping the chat
public class DateParser {
private static DateFormat dateFormat1 = new SimpleDateFormat("dd/MM/yyyy");
public static String convertDateToString(Date date) {
String strDate = "";
strDate = dateFormat1.format(date);
return strDate;
}
}
ChatAdapter.java
public class ChatAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private List<ListObject> listObjects;
private int loggedInUserId;
public ChatAdapter(List<ListObject> listObjects) {
this.listObjects = listObjects;
}
public void setUser(int userId) {
this.loggedInUserId = userId;
}
public void setDataChange(List<ListObject> asList) {
this.listObjects = asList;
//now, tell the adapter about the update
notifyDataSetChanged();
}
#Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
RecyclerView.ViewHolder viewHolder = null;
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
switch (viewType) {
case ListObject.TYPE_GENERAL_RIGHT:
View currentUserView = LayoutInflater.from(parent.getContext()).inflate(R.layout.recyclerview_chat_list_row_right, parent, false);
viewHolder = new ChatRightViewHolder(currentUserView); // view holder for normal items
break;
case ListObject.TYPE_GENERAL_LEFT:
View otherUserView = LayoutInflater.from(parent.getContext()).inflate(R.layout.recyclerview_chat_list_row_left, parent, false);
viewHolder = new ChatLeftViewHolder(otherUserView); // view holder for normal items
break;
case ListObject.TYPE_DATE:
View v2 = inflater.inflate(R.layout.date_row, parent, false);
viewHolder = new DateViewHolder(v2);
break;
}
return viewHolder;
}
#Override
public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
switch (viewHolder.getItemViewType()) {
case ListObject.TYPE_GENERAL_RIGHT:
ChatModelObject generalItem = (ChatModelObject) listObjects.get(position);
ChatRightViewHolder chatViewHolder = (ChatRightViewHolder) viewHolder;
chatViewHolder.bind(generalItem.getChatModel());
break;
case ListObject.TYPE_GENERAL_LEFT:
ChatModelObject generalItemLeft = (ChatModelObject) listObjects.get(position);
ChatLeftViewHolder chatLeftViewHolder = (ChatLeftViewHolder) viewHolder;
chatLeftViewHolder.bind(generalItemLeft.getChatModel());
break;
case ListObject.TYPE_DATE:
DateObject dateItem = (DateObject) listObjects.get(position);
DateViewHolder dateViewHolder = (DateViewHolder) viewHolder;
dateViewHolder.bind(dateItem.getDate());
break;
}
}
#Override
public int getItemCount() {
if (listObjects != null) {
return listObjects.size();
}
return 0;
}
#Override
public int getItemViewType(int position) {
return listObjects.get(position).getType(loggedInUserId);
}
public ListObject getItem(int position) {
return listObjects.get(position);
}
}
ChatRightViewHolder.java for current user message
public class ChatRightViewHolder extends RecyclerView.ViewHolder {
private final String TAG = ChatRightViewHolder.class.getSimpleName();
public ChatRightViewHolder(View itemView) {
super(itemView);
//TODO initialize your xml views
}
public void bind(final ChatModel chatModel) {
//TODO set data to xml view via textivew.setText();
}
}
ChatLeftViewHolder.java for display other user messages.
public class ChatLeftViewHolder extends RecyclerView.ViewHolder {
private final String TAG = ChatRightViewHolder.class.getSimpleName();
public ChatLeftViewHolder(View itemView) {
super(itemView);
//TODO initialize your xml views
}
public void bind(final ChatModel chatModel) {
//TODO set data to xml view via textivew.setText();
}
}
DateViewHolder.java to display date
public class DateViewHolder extends RecyclerView.ViewHolder {
public DateViewHolder(View itemView) {
super(itemView);
//TODO initialize your xml views
}
public void bind(final String date) {
//TODO set data to xml view via textivew.setText();
}
}

You need to create a new ViewHolder for that purpose
For example:
// Different types of rows
private static final int TYPE_ITEM_LEFT = 0;
private static final int TYPE_ITEM_RIGHT = 1;
private static final int TYPE_ITEM_DATE_CONTAINER = 2;
public class MyAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
class ViewHolder0 extends RecyclerView.ViewHolder {
// Viewholder for row type 0
}
class ViewHolder1 extends RecyclerView.ViewHolder {
// Viewholder for row type 1
}
class ViewHolder2 extends RecyclerView.ViewHolder {
// Viewholder for row type 2
}
#Override
public void onBindViewHolder(final RecyclerView.ViewHolder viewHolder, int position) {
if (viewHolder.getItemViewType() == TYPE_ITEM_LEFT) {
// Code to populate type 0 view here
} else if (viewHolder.getItemViewType() == TYPE_ITEM_RIGHT) {
// Code to populate type 1 view here
} else if (viewHolder.getItemViewType() == TYPE_ITEM_DATE_CONTAINER) {
// Code to populate type 2 view here
}
}

You just have to compare the date when scrolling and set the visibility of date view. The advantage of this is there's no hard-coded today/yesterday in data list and is able to refresh the correct date immediately (scrolling) after 12.00 a.m.
e.g. in your onBindViewHolder() in recycleview:
if (position != 0) {
processDate(holder.topDateTextView, myData.getDate()
, this.myDataList.get(position - 1).getDate()
, false)
;
} else {
processDate(holder.topDateTextView, data.getDay()
, null
, true)
;
}
Method to process that date view (Assume your list has format "dd/MM/yyyy"):
private void processDate(#NonNull TextView tv, String dateAPIStr
, String dateAPICompareStr
, boolean isFirstItem) {
SimpleDateFormat f = new SimpleDateFormat("dd/MM/yyyy");
if (isFirstItem) {
//first item always got date/today to shows
//and overkill to compare with next item flow
Date dateFromAPI = null;
try {
dateFromAPI = f.parse(dateAPIStr);
if (DateUtils.isToday(dateFromAPI.getTime())) tv.setText("today");
else if (DateUtils.isToday(dateFromAPI.getTime() + DateUtils.DAY_IN_MILLIS)) tv.setText("yesterday");
else tv.setText(dateAPIStr);
tv.setIncludeFontPadding(false);
tv.setVisibility(View.VISIBLE);
} catch (ParseException e) {
e.printStackTrace();
tv.setVisibility(View.GONE);
}
} else {
if (!dateAPIStr.equalsIgnoreCase(dateAPICompareStr)) {
try {
Date dateFromAPI = f.parse(dateAPIStr);
if (DateUtils.isToday(dateFromAPI.getTime())) tv.setText("today");
else if (DateUtils.isToday(dateFromAPI.getTime() + DateUtils.DAY_IN_MILLIS)) tv.setText("yesterday");
else tv.setText(dateAPIStr);
tv.setIncludeFontPadding(false);
tv.setVisibility(View.VISIBLE);
} catch (ParseException e) {
e.printStackTrace();
tv.setVisibility(View.GONE);
}
} else {
tv.setVisibility(View.GONE);
}
}
}
Note: You also need to do yourAdapter.notifyDataSetChanged(); if append new item to redraw to dismiss previous "today"/date after 12.00 a.m on the same page, not just rely on yourAdapter.notifyItemInserted(new_item_position) which doesn't redraw previous items.