com.firebase.ui.database

Class FirebaseRecyclerAdapter<T,VH extends RecyclerView.ViewHolder>

java.lang.Object

<any>

com.firebase.ui.database.FirebaseRecyclerAdapter<T,VH>

Type Parameters:

T - The Java class that maps to the type of objects stored in the Firebase location.

VH - The ViewHolder class that contains the Views in the layout that is shown for each object.

public abstract class FirebaseRecyclerAdapter<T,VH extends RecyclerView.ViewHolder>
extends <any>

This class is a generic way of backing an RecyclerView with a Firebase location. It handles all of the child events at the given Firebase location. It marshals received data into the given class type. To use this class in your app, subclass it passing in all required parameters and implement the populateViewHolder method.

 
     private static class ChatMessageViewHolder extends RecyclerView.ViewHolder {
         TextView messageText;
         TextView nameText;

         public ChatMessageViewHolder(View itemView) {
             super(itemView);
             nameText = (TextView)itemView.findViewById(android.R.id.text1);
             messageText = (TextView) itemView.findViewById(android.R.id.text2);
         }
     }

     FirebaseRecyclerAdapter<ChatMessage, ChatMessageViewHolder> adapter;
     DatabaseReference ref = FirebaseDatabase.getInstance().getReference();

     RecyclerView recycler = (RecyclerView) findViewById(R.id.messages_recycler);
     recycler.setHasFixedSize(true);
     recycler.setLayoutManager(new LinearLayoutManager(this));

     adapter = new FirebaseRecyclerAdapter<ChatMessage, ChatMessageViewHolder>(ChatMessage.class, android.R.layout.two_line_list_item, ChatMessageViewHolder.class, ref) {
         public void populateViewHolder(ChatMessageViewHolder chatMessageViewHolder, ChatMessage chatMessage, int position) {
             chatMessageViewHolder.nameText.setText(chatMessage.getName());
             chatMessageViewHolder.messageText.setText(chatMessage.getMessage());
         }
     };
     recycler.setAdapter(mAdapter);
 
 

Field Summary

Fields

Modifier and Type	Field and Description
protected int	mModelLayout

Constructor Summary

Constructors

Constructor and Description
FirebaseRecyclerAdapter(java.lang.Class<T> modelClass, int modelLayout, java.lang.Class<VH> viewHolderClass, DatabaseReference ref)
FirebaseRecyclerAdapter(java.lang.Class<T> modelClass, int modelLayout, java.lang.Class<VH> viewHolderClass, Query ref)

Method Summary

Modifier and Type	Method and Description
void	cleanup()
T	getItem(int position)
int	getItemCount()
long	getItemId(int position)
int	getItemViewType(int position)
DatabaseReference	getRef(int position)
void	onBindViewHolder(VH viewHolder, int position)
protected void	onCancelled(DatabaseError databaseError) This method will be triggered in the event that this listener either failed at the server, or is removed as a result of the security and Firebase Database rules.
VH	onCreateViewHolder(android.view.ViewGroup parent, int viewType)
protected T	parseSnapshot(DataSnapshot snapshot) This method parses the DataSnapshot into the requested type.
protected abstract void	populateViewHolder(VH viewHolder, T model, int position) Each time the data at the given Firebase location changes, this method will be called for each item that needs to be displayed.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

mModelLayout

protected int mModelLayout

Constructor Detail

FirebaseRecyclerAdapter

public FirebaseRecyclerAdapter(java.lang.Class<T> modelClass,
                               int modelLayout,
                               java.lang.Class<VH> viewHolderClass,
                               Query ref)

Parameters:

modelClass - Firebase will marshall the data at a location into an instance of a class that you provide

modelLayout - This is the layout used to represent a single item in the list. You will be responsible for populating an instance of the corresponding view with the data from an instance of modelClass.

viewHolderClass - The class that hold references to all sub-views in an instance modelLayout.

ref - The Firebase location to watch for data changes. Can also be a slice of a location, using some combination of limit(), startAt(), and endAt()

FirebaseRecyclerAdapter

public FirebaseRecyclerAdapter(java.lang.Class<T> modelClass,
                               int modelLayout,
                               java.lang.Class<VH> viewHolderClass,
                               DatabaseReference ref)

Parameters:

modelClass - Firebase will marshall the data at a location into an instance of a class that you provide

modelLayout - This is the layout used to represent a single item in the list. You will be responsible for populating an instance of the corresponding view with the data from an instance of modelClass.

viewHolderClass - The class that hold references to all sub-views in an instance modelLayout.

ref - The Firebase location to watch for data changes. Can also be a slice of a location, using some combination of limit(), startAt(), and endAt()

Method Detail

cleanup

public void cleanup()

getItemCount

public int getItemCount()

getItem

public T getItem(int position)

parseSnapshot

protected T parseSnapshot(DataSnapshot snapshot)

This method parses the DataSnapshot into the requested type. You can override it in subclasses to do custom parsing.

Parameters:

snapshot - the DataSnapshot to extract the model from

Returns:

the model extracted from the DataSnapshot

getRef

public DatabaseReference getRef(int position)

getItemId

public long getItemId(int position)

onCreateViewHolder

public VH onCreateViewHolder(android.view.ViewGroup parent,
                             int viewType)

onBindViewHolder

public void onBindViewHolder(VH viewHolder,
                             int position)

getItemViewType

public int getItemViewType(int position)

onCancelled

protected void onCancelled(DatabaseError databaseError)

This method will be triggered in the event that this listener either failed at the server, or is removed as a result of the security and Firebase Database rules.

Parameters:

databaseError - A description of the error that occurred

populateViewHolder

protected abstract void populateViewHolder(VH viewHolder,
                                           T model,
                                           int position)

Each time the data at the given Firebase location changes, this method will be called for each item that needs to be displayed. The first two arguments correspond to the mLayout and mModelClass given to the constructor of this class. The third argument is the item's position in the list.

Your implementation should populate the view using the data contained in the model.

Parameters:

viewHolder - The view to populate

model - The object containing the data used to populate the view

position - The position in the list of the view being populated