Develop Reference

FirebaseRecyclerAdapter model returning null values

I'm trying to make a comment system for posts on my social media app. In my database each post has a section inside of "comments" table, like so:
"hypno--######" is the title of the social media post. It Contains the comment, user id of the user who posted the comment, and a unixtimestamp when the comment was posted. Each comment is titled after the time it was posted.
This is the Comment class
public class comment {
public String uID;
public String comment_t;
public long unixTimestamp;
public comment() {
// Default constructor required for calls to DataSnapshot.getValue(User.class)
}
public comment(String uID, String comment_t, long unixTimestamp) {
this.uID = uID;
this.comment_t = comment_t;
this.unixTimestamp = unixTimestamp;
}
public String getuID() {
return uID;
}
public void setuID(String uID) {
this.uID = uID;
}
public String getComment() {return comment_t;}
public void setComment() {this.comment_t = comment_t; }
public long getUnixTimestamp() {
return unixTimestamp;
}
}
This is the Comment Adapter:
Public class Adapter_Comment extends FirebaseRecyclerAdapter<comment, Adapter_Comment.ViewHolder_com> {
private DatabaseReference mDatabase;
private static final String TAG = "RecyclerViewAdapter";
private Context mContext;
FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
private static AppCompatActivity unwrap(Context context) {
while (!(context instanceof Activity) && context instanceof ContextWrapper) {
context = ((ContextWrapper) context).getBaseContext();
}
return (AppCompatActivity) context;
}
public Adapter_Comment(#NonNull FirebaseRecyclerOptions<comment> options) {
super(options);
//this.mContext = mContext;
}
#NonNull
#Override
public ViewHolder_com onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.layout_comment, parent, false);
mDatabase = FirebaseDatabase.getInstance().getReference();
return new ViewHolder_com(view);
}
#Override
protected void onBindViewHolder(#NonNull ViewHolder_com holder, int position, #NonNull comment model) {
mDatabase = FirebaseDatabase.getInstance().getReference();
long dv = model.getUnixTimestamp()*-1000;
Date df = new java.util.Date(dv);
String vv = new SimpleDateFormat("MM dd, yyyy hh:mma", Locale.ENGLISH).format(df);
holder.time.setText(vv);
String com = model.getComment();
holder.comment_text.setText(com);
mDatabase.child("users").child(model.getuID()).child("profileUrl").addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot snapshot) {
if (snapshot.exists())
{
final String picUrl = snapshot.getValue(String.class);
Glide.with(holder.postPfp.getContext()).load(picUrl).into(holder.postPfp);
}
}
#Override
public void onCancelled(#NonNull DatabaseError error) { }
});
holder.postPfp.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//AppCompatActivity activity = (AppCompatActivity) v.getContext();
AppCompatActivity activity = unwrap(v.getContext());
Fragment OtherProfileFragment = new OtherProfileFragment();
Bundle bundle = new Bundle();
bundle.putString("key", model.getuID());
OtherProfileFragment.setArguments(bundle);
activity.getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, OtherProfileFragment).addToBackStack(null).commit();
}
});
}
public class ViewHolder_com extends RecyclerView.ViewHolder {
TextView comment_text;
CircleImageView postPfp;
TextView time;
RelativeLayout comment_layout;
public ViewHolder_com(#NonNull View itemView) {
super(itemView);
postPfp = itemView.findViewById(R.id.iv_comment_icon);
comment_text = itemView.findViewById(R.id.tv_comment_text);
time = itemView.findViewById(R.id.tv_comment_time);
comment_layout = itemView.findViewById(R.id.comment_layout);
}
}
}
This is Comment Fragment:
public class CommentFragment extends Fragment {
private DatabaseReference mDatabase;
FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
View view;
String value;
RecyclerView recyclerView;
Query query;
TextView comment_text;
long unixTime = System.currentTimeMillis() / 1000L;
public long globalUnix;
Button comment_post;
String comment_string;
Adapter_Comment adapter;
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
view = inflater.inflate(R.layout.fragment_comment, container, false);
value = getArguments().getString("key");
mDatabase = FirebaseDatabase.getInstance().getReference();
recyclerView = view.findViewById(R.id.recyclerv_comment);
comment_text = view.findViewById(R.id.tv_comment_type);
comment_post = view.findViewById(R.id.btn_comment_post);
globalUnix = (unixTime * -1);
comment_post.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(comment_text.getText().toString() == NULL){
Toast.makeText(getActivity(), "No Comment Typed", Toast.LENGTH_LONG).show();
}
else{
comment com = new comment();
com.uID = user.getUid();
com.comment_t = comment_text.getText().toString();
com.unixTimestamp = globalUnix;
mDatabase.child("comments").child(value).child(globalUnix + "").setValue(com);
}
}
});
initRecyclerView();
return view;
}
private void initRecyclerView(){
//Log.d(TAG, "initRecyclerView: init recyclerView");
LinearLayoutManager layoutManager = new LinearLayoutManager(getContext());
recyclerView.setLayoutManager(layoutManager);
query = FirebaseDatabase.getInstance().getReference().child("comments").orderByValue();
FirebaseRecyclerOptions<comment> options = new FirebaseRecyclerOptions.Builder<comment>().setQuery(query, comment.class).build();
adapter = new Adapter_Comment(options);
recyclerView.setAdapter(adapter);
adapter.startListening();
adapter.notifyDataSetChanged();
}
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
}
Inside of the adapter I'm using the comment model, to get the uID, comment and timestamp to fill the holder, however when i set these values im getting null values. Is there something im missing when trying to connect the adapter/firebase and model/holder?
long dv = model.getUnixTimestamp()*-1000;
Date df = new java.util.Date(dv);
String vv = new SimpleDateFormat("MM dd, yyyy hh:mma", Locale.ENGLISH).format(df);
holder.time.setText(vv);
String com = model.getComment();
holder.comment_text.setText(com);
mDatabase.child("users").child(model.getuID()).child("profileUrl").addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot snapshot) {
if (snapshot.exists())
{
final String picUrl = snapshot.getValue(String.class);
Glide.with(holder.postPfp.getContext()).load(picUrl).into(holder.postPfp);
}
}
#Override
public void onCancelled(#NonNull DatabaseError error) { }
});

There's really too much going on in here, but...
As far as I can see you're creating a FirebaseUI adapter on FirebaseDatabase.getInstance().getReference().child("comments"). FirebaseUI adapters show the direct child nodes of the node you pass in, so in your case it'll create one view for the hypno---...196 node. You're trying to read a Comment object from there, but don't exist until one level lower in your JSON.
So you can:
Either show the comments for one post, by basing the adapter off of that. So: FirebaseDatabase.getInstance().getReference().child("comments").child("hypno---...196") (which the real key in there).
Or you can show one piece of information about each post, for example its key.
If you want to show a flat list of comments for all posts through the FirebaseUI adapter, you'll have to store a flat list of comments across all posts in your database too.

Chat Android - Firebase, synchronization delay problems

For months I have created a chat for the Android system using Firebase as a database.
I followed this guide here
( link ) and at the beginning it was all right, the chat was good and it didn't have any kind of delays. I then started to add other particularities, such as the display or not of the message and the status of the participants (online and offline) and from that moment three problems began to manifest in particular:
1) when I change the chat activity to go to another and then return to the chat, the layout appears empty without messages and if you try to change the activity the application closes itself. I found out that I get this error:
E/RecyclerView: No adapter attached; skipping layout
These are the files that make up the part related to chat:
MessageChat.java
public class MessageChat {
private String sender;
private String receiver;
private String msg;
private String currenttime;
private boolean isseen;
public MessageChat(String sender, String receiver, String msg, String currenttime, boolean isseen){
this.sender = sender;
this.receiver = receiver;
this.msg = msg;
this.currenttime = currenttime;
this.isseen = isseen;
}
public MessageChat(){}
public String getSender() {
return sender;
}
public void setSender(String sender) {
this.sender = sender;
}
public String getReceiver() {return receiver;}
public void setReceiver(String receiver) { this.receiver = receiver;}
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
public String getCurrenttime() {
return currenttime;
}
public void setCurrenttime(String currenttime) {
this.currenttime = currenttime;
}
public boolean isIsseen() {return isseen;}
public void setIsseen(boolean isseen) {this.isseen = isseen;}
}
msgAdapter.java
public class msgAdapter extends RecyclerView.Adapter<msgAdapter.MsgViewHolder> {
public static final int INT_TYPE_LEFT = 0;
public static final int INT_TYPE_RIGHT = 1;
private static List<MessageChat> mChat;
private static Context context;
private FirebaseUser fuser;
public msgAdapter(List<MessageChat> msg, Context context) {
this.mChat = msg;
this.context = context;
}
#Override
public msgAdapter.MsgViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType == INT_TYPE_RIGHT) {
View view = LayoutInflater.from(context).inflate(R.layout.right_message, null);
msgAdapter.MsgViewHolder msgViewHolder = new msgAdapter.MsgViewHolder(view);
return msgViewHolder;
}else{
View view = LayoutInflater.from(context).inflate(R.layout.left_message, null);
msgAdapter.MsgViewHolder msgViewHolder = new msgAdapter.MsgViewHolder(view);
return msgViewHolder;
}
}
#Override
public void onBindViewHolder(final msgAdapter.MsgViewHolder holder, final int position) {
MessageChat msg = mChat.get(position);
holder.show_msg.setText(msg.getMsg());
if ((position == mChat.size()-1) && msg.getSender().equals(fuser.getUid())){
if (msg.isIsseen()){
holder.tv_seen.setText(" Seen ");
holder.tv_seen.setVisibility(View.VISIBLE);
}else {
holder.tv_seen.setText(" Sent ");
holder.tv_seen.setVisibility(View.VISIBLE);
}
}else{
holder.tv_seen.setVisibility(View.GONE);
}
}
#Override
public int getItemCount() {
return mChat.size();
}
public static class MsgViewHolder extends RecyclerView.ViewHolder {
TextView username, show_msg, tv_seen;
public MsgViewHolder(final View itemView) {
super(itemView);
show_msg = (TextView) itemView.findViewById(R.id.show_msg);
tv_seen = (TextView) itemView.findViewById(R.id.tv_seen);
itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// item clicked
MessageChat msg = mChat.get(getAdapterPosition());
String ctime = msg.getCurrenttime();
TastyToast.makeText(context, ctime, TastyToast.LENGTH_LONG, TastyToast.INFO);
}
});
}
}
#Override
public int getItemViewType(int position) {
fuser = FirebaseAuth.getInstance().getCurrentUser();
if (mChat.get(position).getSender().equals(fuser.getUid())){
return INT_TYPE_RIGHT;
}else{
return INT_TYPE_LEFT;
}
}
}
On the internet I have found many answers that solve this problem in the following way, replacing this:
View view = LayoutInflater.from(context).inflate(R.layout.right_message, null);
to this:
View view = LayoutInflater.from(context).inflate(R.layout.right_message, parent, false);
But in my case I only got the busted chat with empty spaces between one comic and another.
Homefragment.java
public class HomeFragment extends Fragment {
private HomeViewModel homeViewModel;
private View v;
private ImageButton btn_send;
private EditText et_send_mex;
private DatabaseReference reference;
private msgAdapter mAdapter;
private List<MessageChat> mChat;
private RecyclerView recyclerView;
private FirebaseUser user;
private String Uid, Oid;
private static final String sId = "xyz1";
private static final String pId = "xyz2";
ValueEventListener seenListener;
#Override
public View onCreateView(#NonNull LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
homeViewModel =
ViewModelProviders.of(this).get(HomeViewModel.class);
// Inflate the layout for this fragment
v = inflater.inflate(R.layout.fragment_home, container, false);
btn_send = v.findViewById(R.id.btn_send);
et_send_mex = v.findViewById(R.id.et_send_mex);
recyclerView = v.findViewById(R.id.rv_mex);
recyclerView.setHasFixedSize(true);
LinearLayoutManager llManager = new LinearLayoutManager(getContext());
llManager.setStackFromEnd(true);
recyclerView.setLayoutManager(llManager);
user = FirebaseAuth.getInstance().getCurrentUser();
Uid = user.getUid();
btn_send.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// notify = true;
String m = et_send_mex.getText().toString();
if (!m.equals("") || !m.equals("\n")){
if (Uid.equals(pId)){
sendMessage(Uid,sId,m);
}else if (Uid.equals(sId)){
sendMessage(Uid,pId,m);
}
}
}
});
readMessage();
return v;
}
private void seenMessage(final String senderId){
reference = FirebaseDatabase.getInstance().getReference("chats");
seenListener = reference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot snapshot: dataSnapshot.getChildren()){
MessageChat msgchat = snapshot.getValue(MessageChat.class);
if (msgchat.getReceiver().equals(user.getUid()) && msgchat.getSender().equals(senderId)){
HashMap<String, Object> hashMap = new HashMap<>();
hashMap.put("isseen", true);
snapshot.getRef().updateChildren(hashMap);
}
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}
private void sendMessage(String sender, String receiver, String message){
reference = FirebaseDatabase.getInstance().getReference();
HashMap<String, Object> hashMap = new HashMap<>();
final Calendar c = Calendar.getInstance();
int year = c.get(Calendar.YEAR);
int month = c.get(Calendar.MONTH);
month = month+1;
int day = c.get(Calendar.DAY_OF_MONTH);
int hour = c.get(Calendar.HOUR_OF_DAY);
int sec = c.get(Calendar.MINUTE);
String dt = day+" - "+month+" - "+year+", "+hour+":"+sec;
hashMap.put("currenttime", dt);
hashMap.put("sender", sender);
hashMap.put("receiver", receiver);
hashMap.put("msg", message);
hashMap.put("isseen", false);
reference.child("chats").push().setValue(hashMap);
et_send_mex.setText("");
}
private void readMessage (){
mChat = new ArrayList<>();
mAdapter = new msgAdapter(mChat,getContext());
recyclerView.setAdapter(mAdapter);
reference = FirebaseDatabase.getInstance().getReference("chats");
reference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
mChat.clear();
for (DataSnapshot snapshot: dataSnapshot.getChildren()){
MessageChat chat = snapshot.getValue(MessageChat.class);
mChat.add(chat);
if (!chat.getSender().equals(Uid)){
Oid = chat.getSender();
seenMessage(Oid);
}
}
mAdapter.notifyDataSetChanged();
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}
// user status
private void status(String status){
user = FirebaseAuth.getInstance().getCurrentUser();
reference = FirebaseDatabase.getInstance().getReference("Users").child(user.getUid());
HashMap<String, Object> hashMap = new HashMap<>();
final Calendar c = Calendar.getInstance();
int year = c.get(Calendar.YEAR);
int month = c.get(Calendar.MONTH);
month = month+1;
int day = c.get(Calendar.DAY_OF_MONTH);
int hour = c.get(Calendar.HOUR_OF_DAY);
int sec = c.get(Calendar.MINUTE);
String dt = day+" - "+month+" - "+year+", "+hour+":"+sec;
hashMap.put("lastaccess", dt);
hashMap.put("status", status);
reference.updateChildren(hashMap);
}
#Override
public void onResume() {
super.onResume();
status("online");
recyclerView.setAdapter(mAdapter);
}
#Override
public void onPause() {
super.onPause();
reference.removeEventListener(seenListener);
status("offline");
}
}
I was also advised to add in here:
#Override
public void onResume() {
super.onResume();
status("online");
}
The following code:
recyclerView.setAdapter(mAdapter);
But with poor results (maybe you can suggest me if it is right to add this part here or not, thank you very much)
2) When I send a message, it often takes a long time to reach the database, let's say that Firebase is not really a realtime database. Here I have not encountered any type of error, it is simply very slow.
3) Later I also added the change of state, simply when the application is closed or in background ( onPause () ), the state is set to offline in the database, otherwise it is online. But often it doesn't work properly, probably application crashes or delays affect this.
I remain available for any other part of the code or for clarification.
I thank you in advance for your help and I apologize for my bad English, I have been working on this application since last spring and I still have not been able to solve these problems.

first thing you want to do is, remove the part in your onCreate.
reference = FirebaseDatabase.getInstance().getReference("chats");
reference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
readMessage();
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
Here you basically put a reference on the database (chats) and every time it changes, it will call your function readMessage, which will always override your messages and put another listener on the same spot. Make sure you understand, that addValueEventListener is triggered every time the tree/path (chats) in firebase is updated!
You could simply replace the code from above with:
readMessage();
that would already make sure it is listening to your db. I believe that firebase is not slow, but that the two listeners maybe overriding their result.
About the next part i am not 100%, but i believe you can remove
mAdapter = new msgAdapter(mChat,getContext());
recyclerView.setAdapter(mAdapter);
from onDataChange (in readMessage) and put it directly under that part where you create the ArrayList. Like this:
mChat = new ArrayList<>();
mAdapter = new msgAdapter(mChat,getContext());
recyclerView.setAdapter(mAdapter);
reference = FirebaseDatabase.getInstance().getReference("chats");
I hope i understood your problem and my answer will give you a bit more clarity :)
Greetings!

Retrieve and display data from Firebase in an EditText and edit content and save it again

I want to retrieve data from Firebase and display it in an EditText and allow the user make changes to it if the need arises
This is an android note app using Firebase as the database
I want to retrieve data from Firebase and display it in an EditText and allow the user make changes to it if the need arises.
public class HomeActivity extends AppCompatActivity {
private Toolbar mToolbar;
private FloatingActionButton mFABCreate;
private FirebaseAuth mFirebaseAuth;
private RecyclerView mRecyclerView;
private DatabaseReference mDatabaseReference;
String mPost_Key;
String mKey;
String mTitle;
String mNote;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
mFirebaseAuth = FirebaseAuth.getInstance();
FirebaseUser lFirebaseUser = mFirebaseAuth.getCurrentUser();
assert lFirebaseUser != null;
String uid = lFirebaseUser.getUid();
mDatabaseReference = FirebaseDatabase.getInstance().getReference().child("AllData").child(uid);
mDatabaseReference.keepSynced(true);
mRecyclerView = findViewById(R.id.recycler);
LinearLayoutManager lLinearLayoutManager = new LinearLayoutManager(this);
lLinearLayoutManager.setStackFromEnd(true);
lLinearLayoutManager.setReverseLayout(true);
mRecyclerView.setHasFixedSize(true);
mRecyclerView.setLayoutManager(lLinearLayoutManager);
mToolbar = findViewById(R.id.toolbar);
mToolbar.setTitle("Quick Note");
FloatingActionButton fab = findViewById(R.id.Add_Data);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
finish();
startActivity(new Intent(HomeActivity.this, AddActivity.class));
}
});
}
#Override
protected void onStart() {
super.onStart();
FirebaseRecyclerAdapter<Items, RecyclerViewAdapter> lAdapter = new FirebaseRecyclerAdapter<Items, RecyclerViewAdapter>(
Items.class,
R.layout.show_note,
RecyclerViewAdapter.class,
mDatabaseReference) {
#Override
protected void populateViewHolder(RecyclerViewAdapter recyclerViewAdapter, final Items items, final int i) {
recyclerViewAdapter.setTitle(items.getTitle());
recyclerViewAdapter.setNote(items.getNote());
recyclerViewAdapter.setDate(items.getDate());
recyclerViewAdapter.mView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
mPost_Key = getRef(i).getKey();
mTitle = items.getTitle();
mNote = items.getNote();
editData();
}
});
}
};
mRecyclerView.setAdapter(lAdapter);
}
private void editData(){
startActivity(new Intent(getApplicationContext(), EditActivity.class));
}
public static class RecyclerViewAdapter extends RecyclerView.ViewHolder{
View mView;
public RecyclerViewAdapter(#NonNull View itemView) {
super(itemView);
mView = itemView;
}
public void setTitle (String title){
TextView lTitle = mView.findViewById(R.id.showTitle);
lTitle.setText(title);
}
public void setNote (String note){
TextView lNote = mView.findViewById(R.id.showNote);
lNote.setText(note);
}
public void setDate (String date){
TextView lDate = mView.findViewById(R.id.showDate);
lDate.setText(date);
}
}
}
public class EditActivity extends AppCompatActivity {
private FirebaseAuth mAuth;
private DatabaseReference mDatabaseReference;
private FirebaseDatabase mFirebaseDatabase;
RecyclerView mRecyclerView;
String mPost_Key;
String mTitle, mNote;
String lTitleFire;
String lNoteFire;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_edit);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
final EditText lTitle = findViewById(R.id.YourTitleEdit);
final TextView lNote = findViewById(R.id.Your_Note_Add);
mAuth = FirebaseAuth.getInstance();
mFirebaseDatabase = FirebaseDatabase.getInstance();
mDatabaseReference = mFirebaseDatabase.getReference(mAuth.getUid());
mDatabaseReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
Items lGetValues = dataSnapshot.getValue(Items.class);
assert lGetValues != null;
lTitle.setText(lGetValues.getTitle());
lNote.setText(lGetValues.getNote());
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Toast.makeText(getApplicationContext(), "Getting value failed", Toast.LENGTH_LONG).show();
}
});
}
}
public class Items {
String title;
String note;
String date;
String id;
public Items() {
}
public Items(String title, String note, String date, String id) {
this.title = title;
this.note = note;
this.date = date;
this.id = id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getNote() {
return note;
}
public void setNote(String note) {
this.note = note;
}
public String getDate() {
return date;
}
public void setDate(String date) {
this.date = date;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
}
Firebase data:
AllData
nakrU3ArQNShLzyn9U8X9fAFNeL2
-LopLNpUFmepM8gvCmHS
date:
id:
note:
title:
My aim is to set the values gotten from Firebase and display it into the "EditActivity"

it just display blank EditText
Assuming you get no errors, and there isn't empty strings saved in Firebase values, if you look at the data in Firebase, you have two ID values, yet you are only querying for the top one
AllData
nakrU3ArQNShLzyn9U8X9fAFNeL2 # Uid
-LopLNpUFmepM8gvCmHS # a specific item
You'll need to add another reference to the specific item, then add the value listener to that for it to show in the EditText. For example,
String itemId = ...;
mDatabaseReference.child(itemId)
.addValueEventListener(...
In order to get that id, you'll need to pass it to the next activity when you click it like so
editData(getRef(i).getKey());
Therefore, in that editData method, pass the id as an Intent extra so it can be found by the EditActivity
private void editData(String itemId) {
Intent intent = new Intent(HomeActivity.this, EditActivity.class);
intent.putExtra("EXTRA_ITEM_ID", itemId);
startActivity(intent);
}
Then over in the EditActivity, you need to get and use the item ID to query for a specific item
String itemId = getIntent().getStringExtra("EXTRA_ITEM_ID");
// wouldn't hurt to log the ID value for debugging here
mDatabaseReference.child(itemId)
.addValueEventListener(...
Then keep everything else you already have
That should at least display something...
Then you'll want to add a save button somewhere so that you can write the value back to Firebase, as it won't save automatically as you type (unless you implement that, but I wouldn't recommend that because it'll create a lot of unnecessary network calls)
Items toSave =...
mDatabaseReference.child(itemId).setValue(toSave);

Android: reading a value from a child with FirebaseUI

I am using FirebaseUI to get some values from my real-time database to Firebase RecyclerView. So.. my data looks like that:
users:
userid:
info:
Name:Muhammad
I don't know how to get the value of Name which means what exactly should I do in the Users class? Here is my code (I think that the problem is in class user, I just don't know how to access child info)
public class User {
private String name;
private String email;
private String state;
private String image;
private String thumbnail;
public User(String name, String state, String image) {
this.name = name;
this.state = state;
this.image = image;
}
public User() {
}
public String getName() {
return name;
}
public String getState() {
return state;
}
public String getImage() {
return image;
}
}
my Main Activity
myDB refer to and on start method (updated after SUPERCILEX comment )
mDb = FirebaseDatabase.getInstance().getReference().child(App_Constants.USERS_COLUMN);
#Override
protected void onStart() {
super.onStart();
Query query = mDb;
FirebaseRecyclerOptions<User> options = new FirebaseRecyclerOptions.Builder<User>()
.setQuery(query, new SnapshotParser<User>() {
#NonNull
#Override
public User parseSnapshot(#NonNull DataSnapshot snapshot) {
String Name = snapshot.child(App_Constants.INFO_COLUMN).child(App_Constants.NAME_COLUMN).getValue().toString();
String State = snapshot.child(App_Constants.INFO_COLUMN).child(App_Constants.STATE_COLUMN).getValue().toString();
String Image = snapshot.child(App_Constants.INFO_COLUMN).child(App_Constants.IMAGE_COLUMN).getValue().toString();
User user = new User(Name,State,Image);
return user;
}
}).build();
FirebaseRecyclerAdapter<User,Users_ViewHolder> adapter = new FirebaseRecyclerAdapter<User, Users_ViewHolder>(options) {
#NonNull
#Override
public Users_ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.single_user,parent,false);
return new Users_ViewHolder(view);
}
#Override
protected void onBindViewHolder(#NonNull Users_ViewHolder holder, int position, #NonNull User model) {
holder.Set_Name(model.getName());
holder.Set_Image(model.getImage());
holder.Set_State(model.getState());
}
};
mUsers.setAdapter(adapter);
}
my ViewHolder
public class Users_ViewHolder extends RecyclerView.ViewHolder{
View mView;
public Users_ViewHolder(View itemView) {
super(itemView);
mView = itemView;
}
public void Set_Name(String Name)
{
TextView mName = mView.findViewById(R.id.tv_single_user_name);
mName.setText(Name);
}
public void Set_Image(String url)
{
CircleImageView mImage = mView.findViewById(R.id.iv_single_user);
Picasso.get().load(url).placeholder(R.drawable.profile).into(mImage);
}
public void Set_State(String State)
{
TextView mState = mView.findViewById(R.id.tv_single_user_state);
mState.setText(State);
}
}
thanks

I believe it'll come in as a Map<String, Object> on the field info. However, you can always use a custom SnapshotParser to build your model to your liking: https://github.com/firebase/FirebaseUI-Android/blob/master/database/README.md#using-the-firebaserecycleradapter.

Some Advices :would you mind changing the set methods names?
from Set_State to setState,I too had similar problems please respect Java naming conventions
Also add the set methods in your custom model
Second:
FirebaseRecyclerOptions<User> options =
new FirebaseRecyclerOptions.Builder<User>()
.setQuery(query, User.class)
.build();
Start Listening:
#Override
protected void onStart() {
super.onStart();
adapter.startListening();
}
stopListening() call removes the event listener and all data in the adapter
#Override
protected void onStop() {
super.onStop();
adapter.stopListening();
}
Here you have a very good explained example

unable to retrieve data from one app to another app from firebase single Database

I have 2 applications(different package names) which use one Firebase database. One app has to write access to the database and another have read access to the database.in my second application, i use recyclerview to retrieve data which is stored by 1st App.
for this I use below code:
FirebaseOptions options = new FirebaseOptions.Builder()
.setApplicationId("1:567....259c8f58311") // Required for Analytics.
.setApiKey("AIzaSyA9BRxl......hE03y5qD-c") // Required for Auth.
.setDatabaseUrl("https://mycity-3a561.firebaseio.com/") // Required for RTDB.
.build();
FirebaseApp.initializeApp(this /* Context */, options, "MyCity");
// Retrieve my other app.
FirebaseApp app = FirebaseApp.getInstance("MyCity");
// Get the database for the other app.
FirebaseDatabase secondaryDatabase = FirebaseDatabase.getInstance(app);
DatabaseReference data = secondaryDatabase.getInstance().getReference();
data.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot snapshot) {
for (DataSnapshot ds : snapshot.getChildren()) {
for (DataSnapshot dSnapshot : ds.getChildren()) {
WaterClass waterClass = dSnapshot.getValue(WaterClass.class);
Log.d("Show", waterClass.getName() == null ? "" : waterClass.getName());
list.add(waterClass);
}
adapter = new WaterAdapter(ShowWaterDetails.this, list);
recyclerView.setAdapter(adapter);
adapter.notifyDataSetChanged();
progressDialog.dismiss();
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
progressDialog.dismiss();
}
});
}
Adapter class
private class WaterAdapter extends RecyclerView.Adapter<WaterAdapter.ViewHolder> {
ShowWaterDetails showDetail;
List<WaterClass> listData;
public WaterAdapter(ShowWaterDetails showWaterDetails, List<WaterClass> list) {
this.showDetail = showWaterDetails;
this.listData = list;
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.show_items, parent, false);
WaterAdapter.ViewHolder viewHolder = new WaterAdapter.ViewHolder(view);
return viewHolder;
}
#Override
public void onBindViewHolder(WaterAdapter.ViewHolder holder, int position) {
WaterClass AllDetails = listData.get(position);
holder.NameTextView.setText(AllDetails.getName());
holder.DetailTextView.setText(AllDetails.getDetail());
holder.DateTextView.setText(AllDetails.getDate());
holder.LocationTextView.setText(AllDetails.getLocation());
holder.TypeTextView.setText(AllDetails.getType());
Picasso.with(showDetail).load(AllDetails.getImgurl()).resize(120, 60).into(holder.ImageTextView);
}
#Override
public int getItemCount() {
return listData.size();
}
class ViewHolder extends RecyclerView.ViewHolder {
public TextView NameTextView;
public TextView DetailTextView;
public TextView DateTextView;
public TextView LocationTextView;
public TextView TypeTextView;
public ImageView ImageTextView;
public ViewHolder(View itemView) {
super(itemView);
NameTextView = itemView.findViewById(R.id.ShowNameTextView);
DetailTextView = itemView.findViewById(R.id.ShowDetailTextView);
DateTextView = itemView.findViewById(R.id.ShowDateTextView);
LocationTextView = itemView.findViewById(R.id.ShowLocationTextView);
TypeTextView = itemView.findViewById(R.id.ShowTypeTextView);
ImageTextView = itemView.findViewById(R.id.ShowImageView);
}
}
}
}
POJO Class
class WaterClass {
private String id;
private String email;
private String name;
private String type;
private String detail;
private String location;
private String date;
private String imgurl;
public WaterClass(){
}
public WaterClass(String id, String currentUserString, String imageUrl, String nameString, String typeString, String detailString, String locationString, String dateString) {
this.id = id;
this.email = currentUserString;
this.name =nameString;
this.type = typeString;
this.detail = detailString;
this.location = locationString;
this.date = dateString;
this.imgurl = imageUrl;
}
public String getImgurl() {
return imgurl;
}
public void setImgurl(String imgurl) {
this.imgurl = imgurl;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public String getDetail() {
return detail;
}
public void setDetail(String detail) {
this.detail = detail;
}
public String getLocation() {
return location;
}
public void setLocation(String location) {
this.location = location;
}
public String getDate() {
return date;
}
public void setDate(String date) {
this.date = date;
}
}
:
there is no error but my recycler not showing anything

go to onStart() and start listening
#Override
protected void onStart() {
super.onStart();
adapter.startListening();
}
and in your onStop
#Override
protected void onStop() {
super.onStop();
adapter.stopListening();
}
The FirebaseRecyclerAdapter uses a snapshot listener to monitor changes to the Firestore query. To begin listening for data, call the startListening() method. You may want to call this in your onStart() method. Make sure you have finished any authentication necessary to read the data before calling startListening() or your query will fail.
Be sure that the names of constant in the POJO match exatly the names
of your database structure in your firebase console !!
ps: do not post your api-keys or app-ids in your questions, keep them secret, and consider using firebaserecycleradapter if you are using firebase-database , it will be more easy to setup and to show values.
Your POJO is ok !

Found Solution!!
just change this part of a code
FirebaseApp.initializeApp(this /* Context */, options, "MyCity");
// Retrieve my other app.
FirebaseApp app = FirebaseApp.getInstance("MyCity");
TO
FirebaseApp.initializeApp(this);
// Retrieve my other app.
FirebaseApp app = FirebaseApp.getInstance("[DEFAULT]");