Obtaining user ID from database and using that ID in the database reference for FirebaseRecyclerView

I understand this isn’t particularly an issue, and I can’t find anything online to help me with this.

I have a MainActivity class that signs the user in with Firebase and gets the current user there, and assigns it to a global static clientUser variable. I have a fragment in another class (that the MainActivity uses) that contains the FirebaseRecyclerView and uses the clientUser object to get its firebase ID.

How would I add that user’s firebase ID into a database reference so that my FirebaseRecyclerView loads up that particular user’s groups from the database into the RecyclerView?

Basically, I get a null ptr exception at the initialization of mRef here because clientUser has not been created yet, because Firebase didnt log in yet. Any help/advice would be appreciated!

       DatabaseReference mRef = FirebaseDatabase.getInstance().getReference().child("users").child(clientUser.get_fb_uid()).child(groups);

        groupRecyclerViewAdapter = new FirebaseRecyclerAdapter<Group, GroupHolder>(Group.class, R.layout.grouptask_item, GroupHolder.class, mRef) {
            @Override
            protected void populateViewHolder(GroupHolder viewHolder, Group group, int position) {
                viewHolder.setCardGroupName(group.getGroupName());
                viewHolder.setGroupMemberCount(group.getMembers().size());
                viewHolder.setCardAuthorProfileImg(group.getAuthorProfilePictureUrl());
            }
        };

Never mind! After hours of experimenting I realized I can just add the following in my fragment class!

@Override
 public View onCreateView(LayoutInflater inflater, ViewGroup container,
                          Bundle savedInstanceState) {



     View view = inflater.inflate(R.layout.grouptask_item_list, container, false);

     itemTouchHelper = new ItemTouchHelper(simpleCallbackItemTouchHelper);

     Context context = view.getContext();
     recyclerView = (RecyclerView) view;
     recyclerView.setHasFixedSize(false);

     recyclerView.setLayoutManager(new LinearLayoutManager(context));


     final DatabaseReference mRef = FirebaseDatabase.getInstance().getReference().child("users");

     mAuth = FirebaseAuth.getInstance();

     mAuthListener = new FirebaseAuth.AuthStateListener() {
         @Override
         public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
             FirebaseUser user = firebaseAuth.getCurrentUser();
             if (user != null) {

                 Log.d(TAG, "User signed in... Collecting FireBase currentUser info");
                 // Currently signed in
                 
                 groupRecyclerViewAdapter = new FirebaseRecyclerAdapter<Group, GroupHolder>(Group.class, R.layout.grouptask_item, GroupHolder.class, mRef.child(user.getUid()).child("groups")) {
                     @Override
                     protected void populateViewHolder(GroupHolder viewHolder, Group group, int position) {
                         viewHolder.setCardGroupName(group.getGroupName());
                         viewHolder.setGroupMemberCount(group.getMembers().size());
                         viewHolder.setCardAuthorProfileImg(group.getAuthorProfilePictureUrl());
                     }
                 };

                 recyclerView.setAdapter(groupRecyclerViewAdapter);



             } else {
                 Log.d(TAG, "User is currently signed out");
             }
         }
     };

     itemTouchHelper.attachToRecyclerView(recyclerView);

     return view;
 }

[SUPERCILEX]

@Joroze You should probably wait for the user to sign in… Firebase Auth provides a nice callback for this:

@Override
public void onAuthStateChanged(@NonNull FirebaseAuth auth) {
    if (auth.getCurrentUser() == null) {
        // Not signed in
    } else {
        // Signed in, init your Firebase recyclerview here
    }
}

In your onCreate and onDestroy:

FirebaseAuth.getInstance().addAuthStateListener(this); // In onCreate

FirebaseAuth.getInstance().removeAuthStateListener(this); // In onDestroy

PS: You really shouldn’t be storing the uid in a static variable. That will be full of bugs and weirdness when Android tries to restore your activities from a saved state. Use FirebaseAuth.getInstance().getCurrentUser().getUid() insead.

[SUPERCILEX]

@Joroze You’re welcome! 😄