title: Problem with a searching users in a search Fragment androidStudio & Firebase
body: <p>I'm trying to do a basic social app but the search Fragment which is in the main activity makes the application crash with the error code : "java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference"</p>
  
  <p>The message says that i'm trying to do a if() statement on a null object which is not supposed to be. The error is at the if at the end of the following code:</p>
  
  <pre><code>@Override
   public void onBindViewHolder(@NonNull final ViewHolder viewHolder, int position) {
      firebaseUser = FirebaseAuth.getInstance().getCurrentUser();
  
      final UserObject user = mUsers.get(position);
  
      viewHolder.username.setText(user.getUsername());
      Glide.with(context).load(user.getImageurl()).into(viewHolder.image_profile);
      isFollowing(user.getId(), viewHolder.follow);
  
      if(user.getId().equals(firebaseUser.getUid())){
          viewHolder.follow.setVisibility(View.GONE);
      }
  
     This is suppose to hide a follow button when the user object has the 
     user id.
  
   for (DataSnapshot snapshot : dataSnapshot.getChildren()){
                      User user = snapshot.getValue(User.class);
                      mUsers.add(user);
                  }
  </code></pre>