Recyclerview keeps re-populating data from Firebase DB when new child is created

I am currently working on a chat application and have come across an issue. My Chat Fragment contains my Recyclerview which populates data from Firebase DB. I am able to obtain the data, but I am running into an issue. When I open my Chat Activity and send a message, a new push id is created with the information stored in the child. The data obtained by my recyclerview is it gets the last push id and retrieves the last message that was sent. The problem is, when I go back into my fragment, the recyclerview re-populates and adds the new push id last message that was created, and creates another item instead of just refreshing the original item.

Chat Fragment

Recyclerview

Firebase DB

Chat Activity

push id

recyclerview

push id

fragment

push id

So essentially, I will load my app, go into the Chat Fragment, my recyclerview will display the other user and the last message that was sent, no problem, then I will click on that item, open the chat activity, send a message then go back. Now when I am back into the chat fragment I will have two or three or however many messages that were sent displaying in the recyclerview. Not sure on how to fix this, my code is below:

Chat Fragment

recyclerview

chat activity

chat fragment

recyclerview

DATABASE STRUCTURE

Chat Fragment

public class Fragment_MatchChats extends Fragment
private RecyclerView mRecyclerView, mRecyclerViewChat;
private RecyclerView.Adapter mMatchesAdapter, mChatAdapter;
private String currentUserID;
private DatabaseReference mDatabaseChat;

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState)
View v = inflater.inflate(R.layout.frag_match_chat, container, false);


currentUserID = FirebaseAuth.getInstance().getCurrentUser().getUid();
mDatabaseChat = FirebaseDatabase.getInstance().getReference().child("Chat");
LinearLayoutManager layoutManagerChat = new LinearLayoutManager(getContext(), LinearLayoutManager.VERTICAL, false);
mRecyclerViewChat = (RecyclerView) v.findViewById(R.id.recyclerViewChat);
mRecyclerViewChat.setHasFixedSize(true);
mRecyclerViewChat.setLayoutManager(layoutManagerChat);

mChatAdapter = new RecyclerViewChatAdapter(getDataSetChat(), getContext());

getUserMatchId();
return v;



//this method will get the user ID in the database that you matched with. It will run through the matches child and get all the user IDs
private void getUserMatchId()
DatabaseReference matchDB = FirebaseDatabase.getInstance().getReference().child("Users").child(currentUserID).child("swipes").child("matches");
matchDB.addListenerForSingleValueEvent(new ValueEventListener()
@Override
public void onDataChange(DataSnapshot dataSnapshot)
if (dataSnapshot.exists())
for(DataSnapshot match : dataSnapshot.getChildren())
CheckChatID(match.getKey());




@Override
public void onCancelled(DatabaseError databaseError)


);


private void CheckChatID(final String chat)
DatabaseReference ChatDB = FirebaseDatabase.getInstance().getReference().child("Users").child(currentUserID).child("swipes").child("matches")
.child(chat).child("ChatID");
ChatDB.addListenerForSingleValueEvent(new ValueEventListener()
@Override
public void onDataChange(DataSnapshot dataSnapshot)
if (dataSnapshot.exists())
String ChatID = dataSnapshot.getValue().toString();
ChatIDExist(ChatID, chat);



@Override
public void onCancelled(DatabaseError databaseError)


);


private void ChatIDExist(final String chatID, final String oppUserID)
final DatabaseReference ChatDB = mDatabaseChat.child(chatID);
final Query lastQuery = ChatDB.orderByKey().limitToLast(1);
ChatDB.addListenerForSingleValueEvent(new ValueEventListener()
@Override
public void onDataChange(DataSnapshot dataSnapshot)
if (dataSnapshot.exists())
lastQuery.addValueEventListener(new ValueEventListener()
@Override
public void onDataChange(DataSnapshot dataSnapshot)
for(DataSnapshot child: dataSnapshot.getChildren())
String key = child.child("text").getValue().toString();
FetchChatInfo(oppUserID,key);




@Override
public void onCancelled(DatabaseError databaseError)


);




@Override
public void onCancelled(DatabaseError databaseError)


);


private void FetchChatInfo(String key, final String chatID)
DatabaseReference userDB = FirebaseDatabase.getInstance().getReference().child("Users").child(key);
userDB.addListenerForSingleValueEvent(new ValueEventListener()
@Override
public void onDataChange(DataSnapshot dataSnapshot)
if(dataSnapshot.exists())
String matched_userID = dataSnapshot.getKey();
String matches_userName = "";
String matches_userProPic = "";
String match_CHATID = chatID;

if(dataSnapshot.child("name").getValue() != null)
matches_userName = dataSnapshot.child("name").getValue().toString();

if(dataSnapshot.child("profilePicURL").getValue() != null)
matches_userProPic = dataSnapshot.child("profilePicURL").getValue().toString();



RecyclerViewChatReference chat_obj = new RecyclerViewChatReference(matched_userID, matches_userName, matches_userProPic, match_CHATID);
resultsChats.add(chat_obj);
mRecyclerViewChat.setAdapter(mChatAdapter);
mChatAdapter.notifyDataSetChanged();




@Override
public void onCancelled(DatabaseError databaseError)


);


private ArrayList<RecyclerViewChatReference> resultsChats = new ArrayList<RecyclerViewChatReference>();

private List<RecyclerViewChatReference> getDataSetChat()
return resultsChats;



Chat Activity

protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_chat);

matchId = getIntent().getExtras().getString("matchID");

currentUserID = FirebaseAuth.getInstance().getCurrentUser().getUid();

mDatabaseUser = FirebaseDatabase.getInstance().getReference().child("Users").child(currentUserID)
.child("swipes").child("matches").child(matchId).child("ChatID");
mDatabaseChat = FirebaseDatabase.getInstance().getReference().child("Chat");

getChatId();

mRecyclerView = (RecyclerView) findViewById(R.id.recyclerView);
mRecyclerView.setNestedScrollingEnabled(false);
mRecyclerView.setHasFixedSize(false);
mChatLayoutManager = new LinearLayoutManager(ChatActivity.this);
mRecyclerView.setLayoutManager(mChatLayoutManager);
mChatAdapter = new ChatAdapter(getDataSetChat(), ChatActivity.this);
mRecyclerView.setAdapter(mChatAdapter);

mSendEditText = findViewById(R.id.message);
mSendButton = findViewById(R.id.send);

mSendButton.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View view)
sendMessage();

);




private void sendMessage()
String sendMessageText = mSendEditText.getText().toString();

if(!sendMessageText.isEmpty())
DatabaseReference newMessageDb = mDatabaseChat.push();

Map newMessage = new HashMap();
newMessage.put("createdByUser", currentUserID);
newMessage.put("text", sendMessageText);

newMessageDb.setValue(newMessage);

mSendEditText.setText(null);


private void getChatId()
mDatabaseUser.addListenerForSingleValueEvent(new ValueEventListener()
@Override
public void onDataChange(DataSnapshot dataSnapshot)
if (dataSnapshot.exists())
chatId = dataSnapshot.getValue().toString();
mDatabaseChat = mDatabaseChat.child(chatId);
getChatMessages();



@Override
public void onCancelled(DatabaseError databaseError)


);


private void getChatMessages()
mDatabaseChat.addChildEventListener(new ChildEventListener()
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s)
if(dataSnapshot.exists())
String message = "";
String createdByUser = "";

if(dataSnapshot.child("text").getValue()!=null)
message = dataSnapshot.child("text").getValue().toString();

if(dataSnapshot.child("createdByUser").getValue()!=null)
createdByUser = dataSnapshot.child("createdByUser").getValue().toString();


if(message!=null && createdByUser!=null)
Boolean currentUserBoolean = false;
if(createdByUser.equals(currentUserID))
currentUserBoolean = true;

ChatObject newMessage = new ChatObject(message, currentUserBoolean);
resultsChat.add(newMessage);
mChatAdapter.notifyDataSetChanged();




@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)

);



private ArrayList<ChatObject> resultsChat = new ArrayList<ChatObject>();
private List<ChatObject> getDataSetChat()
return resultsChat;

}


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