Get the userId (or interact with other users) in Firebase Database - firebase

Question

I am building a chat app with Firebase and I am having issues identifying who is who, when a user sends another user a message, he needs to post it to the receivers node and he needs to know his UID to do that. I need to know how to get the receiver's UID, so I can post directly to his own node.
I tried using intent.putExtra and intent.getExtras from my MainActivity which lists out every user from their directories, this is my current code that does not successfully pass the data I need.
public static class PlaceholderFragment extends Fragment {
private DatabaseReference mDatabase;
private FirebaseAuth mAuth;
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
public PlaceholderFragment() {
}
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public static class UserHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
View mView;
public UserHolder(View itemView) {
super(itemView);
itemView.setOnClickListener(this);
mView = itemView;
}
public void setName(String name) {
TextView field = (TextView) mView.findViewById(R.id.thename);
field.setText(name);
}
public void setImage(String image){
ImageView pp = (ImageView) mView.findViewById(R.id.imageurl);
try{
Picasso.with(Application.getAppContext()).load(image).placeholder(R.drawable.nodp).error(R.drawable.nodp).transform(new CircleTransform()).into(pp);
}
catch (IllegalArgumentException e){
Picasso.with(Application.getAppContext()).load(R.drawable.nodp).transform(new CircleTransform()).into(pp);
}
}
#Override
public void onClick(View mView) {
//what to do here
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
TextView textView = (TextView) rootView.findViewById(R.id.section_label);
//textView.setText(getString(R.string.section_format, getArguments().getInt(ARG_SECTION_NUMBER)));
//private static final String TAG = "UserListActivity";
//final TextView name = (TextView) rootView.findViewById(R.id.lastname) ;
//final ImageView profileImage = (ImageView) rootView.findViewById(R.id.imageView4);
mAuth = FirebaseAuth.getInstance();
FirebaseUser user = mAuth.getCurrentUser();
final DatabaseReference root = FirebaseDatabase.getInstance().getReference();
DatabaseReference userRef = root.child("users");
RecyclerView recycler = (RecyclerView) rootView.findViewById(R.id.recyclerview3);
recycler.setHasFixedSize(true);
recycler.setLayoutManager(new LinearLayoutManager(getActivity()));
FirebaseRecyclerAdapter mAdapter = new FirebaseRecyclerAdapter<UserList, UserHolder>(UserList.class, R.layout.userlistrow, UserHolder.class, userRef) {
#Override
public void populateViewHolder(UserHolder userViewHolder, final UserList userList, final int position) {
//try catch block to catch events of no posts, it will most likely return a null error, so im catching it, else
//find its exception and catch it
try {
String firstname = userList.getFirstname().toString();
String lastname = userList.getLastname().toString();
firstname = firstname.substring(0, 1).toUpperCase() + firstname.substring(1); //convert first string to uppercase
lastname = lastname.substring(0, 1).toUpperCase() + lastname.substring(1);// same thing happening here
String name = (firstname + " " + lastname); // concatenate firstname and lastname variable.
userViewHolder.setName(name);
}
catch(NullPointerException e) {
String firstname = "Not";
String lastname = "set";
String name = (firstname + " " + lastname );
userViewHolder.setName(name);
}
catch (StringIndexOutOfBoundsException e) {
String firstname = "No";
String lastname = "name";
String name = (firstname + " " + lastname );
userViewHolder.setName(name);
}
//note that picasso view holder was applied in the view holder instead
//String image = userList.getImgUrl().toString();
//userViewHolder.setImage(image);
//findViewById(R.id.progressBar3).setVisibility(View.GONE);
This is where I am passing the extras, and it doesnt seem to work
userViewHolder.mView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
//Log.w(TAG, "You clicked on "+position);
//String firstname = userList.getFirstname();
//String lastname = userList.getLastname();
//firstname = firstname.substring(0, 1).toUpperCase() + firstname.substring(1); //convert first string to uppercase
//lastname = lastname.substring(0, 1).toUpperCase() + lastname.substring(1);// same thing happening here
//String name = (firstname + " " + lastname); // concatenate firstname and lastname variable.
Intent intent = new Intent(getActivity(), Userdetail.class); //change to onclick
intent.putExtra("userId", userList.getUserId());//you can name the keys whatever you like
intent.putExtra("lastname", userList.getLastname().toString());
intent.putExtra("firstname", userList.getFirstname().toString());
intent.putExtra("image", userList.getImgUrl().toString()); //note that all these values have to be primitive (i.e boolean, int, double, String, etc.)
startActivity(intent);
}
});
}
};
recycler.setAdapter(mAdapter);
return rootView;
}
}
If you need more information, please ask in the comments. Ive googled around but no help
package com.mordred.theschoolapp;
import com.google.firebase.database.IgnoreExtraProperties;
/**
* Created by mordred on 11/28/16.
*/
public class UserList {
public String firstname;
public String lastname;
public String userId;
public String imgUrl;
public UserList() {
// Default constructor required for calls to DataSnapshot.getValue(User.class)
}
public String getFirstname() {
return firstname;
}
public void setFirstname(String firstname) {
this.firstname = firstname;
}
public String getLastname() {
return lastname;
}
public void setLastname(String lastname) {
this.lastname = lastname;
}
public String getImgUrl() {
return imgUrl;
}
public void setImgUrl(String imgUrl) {
this.imgUrl = imgUrl;
}
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
}