im developing an android chat using firebase.
i tried to research about this problem but i cant find a good solutions.
hope someone can help me.
my problem i want the RecyclerView to auto scroll if new item is added.
here is my code.
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
View rootView = inflater.inflate(R.layout.chatlayoutchat, container, false);
Connectivity connectivity=new Connectivity();
if(connectivity.isConnected(getActivity())) {
if(getArguments() != null) {
Firebase.setAndroidContext(this.getActivity());
String ccustomersid = getArguments().getString("customersid");
String creferralae = getArguments().getString("referralae");
String ccustomersname = getArguments().getString("customersname");
customersid = ccustomersid;
referralae = creferralae;
customersname = ccustomersname;
Firebase.setAndroidContext(this.getActivity());
editText = (EditText) rootView.findViewById(R.id.editText);
sendbutton = (Button) rootView.findViewById(R.id.button);
mRecyclerView = (RecyclerView) rootView.findViewById(R.id.recycler_view);
RecyclerView.LayoutManager layoutmgr = new LinearLayoutManager(getActivity());
mRecyclerView.setLayoutManager(layoutmgr);
mRecyclerView.setItemAnimator(new DefaultItemAnimator());
final LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity());
//linearLayoutManager.setReverseLayout(true);
linearLayoutManager.setStackFromEnd(true);
mRecyclerView.setLayoutManager(linearLayoutManager);
from_user = customersid;
to_user = referralae;
LoggedInUser = customersname;
//Log.v("NODE CREATED:", from_user + " " + to_user);
ref_chatchildnode1 = firebase_chatnode.child(from_user + " " + to_user);
//ref_chatchildnode2 = firebase_chatnode.child(to_user + " " + from_user);
sendbutton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
newmsg = editText.getText().toString().trim();
ChatModel m = new ChatModel();
m.setSender(LoggedInUser);
m.setMessage(newmsg);
ref_chatchildnode1.push().setValue(m);
//ref_chatchildnode2.push().setValue(m);
editText.setText("");
}
});
ref_chatchildnode1.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
ChatModel chatmsg = dataSnapshot.getValue(ChatModel.class);
chatmsgsList.add(chatmsg);
}
@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(FirebaseError firebaseError) {
}
});
}
}else{
nointernet();
}
showGlobalContextActionBar();
return rootView;
}
@Override
public void onStart() {
super.onStart();
mFirebaseAdapter1 = new FirebaseRecyclerAdapter<ChatModel, ChatMessageViewHolder>(ChatModel.class,
R.layout.textview,
ChatMessageViewHolder.class,
ref_chatchildnode1) {
@Override
protected void populateViewHolder(ChatMessageViewHolder chatMessageViewHolder, ChatModel m, int i) {
chatMessageViewHolder.sender.setText(m.getSender());
chatMessageViewHolder.msg.setText(m.getMessage());
}
};
mRecyclerView.setAdapter(mFirebaseAdapter1);
}
Have a look at step 6 of the Firebase codelab for Android, which uses an AdapterDataObserver for this:
mFirebaseAdapter.registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {
@Override
public void onItemRangeInserted(int positionStart, int itemCount) {
super.onItemRangeInserted(positionStart, itemCount);
int friendlyMessageCount = mFirebaseAdapter.getItemCount();
int lastVisiblePosition =
mLinearLayoutManager.findLastCompletelyVisibleItemPosition();
// If the recycler view is initially being loaded or the
// user is at the bottom of the list, scroll to the bottom
// of the list to show the newly added message.
if (lastVisiblePosition == -1 ||
(positionStart >= (friendlyMessageCount - 1) &&
lastVisiblePosition == (positionStart - 1))) {
mMessageRecyclerView.scrollToPosition(positionStart);
}
}
});
Just try below code :
@Override
public void onStart() {
super.onStart();
mFirebaseAdapter1 = new FirebaseRecyclerAdapter<ChatModel, ChatMessageViewHolder>(ChatModel.class,
R.layout.textview,
ChatMessageViewHolder.class,
ref_chatchildnode1) {
@Override
protected void populateViewHolder(ChatMessageViewHolder chatMessageViewHolder, ChatModel m, int i) {
chatMessageViewHolder.sender.setText(m.getSender());
chatMessageViewHolder.msg.setText(m.getMessage());
}
};
mRecyclerView.setAdapter(mFirebaseAdapter1);
if (mFirebaseAdapter1 != null) {
mRecyclerView.postDelayed(new Runnable() {
@Override
public void run() {
mRecyclerView.smoothScrollToPosition(mFirebaseAdapter1.getItemCount() - 1);
}
}, 5);
}
}
I know it is an old thread, but maybe this will be helpful.
In place where you add new message:
yourRVAdapter.addMessage("New message")
val position = yourRVAdapter.itemCount.minus(1) // itemCount will return the size of RV items
//Now just call your recyclerView.scrollToPosition(int)
chatRV.scrollToPosition(position)
来源：https://stackoverflow.com/questions/40797430/android-firebase-chat-recyclerview-auto-scroll-to-bottom-when-new-item-is-added