title: Firebase Android - startAt() and endAt() not working correctly?
body: <p>How do I search for users based on their usernames? I have looked at numerous SO posts on this matter but am still unable to achieve what I want to do.. I have tried to apply what I saw in those posts and is shown below:</p>
  
  <pre><code>DatabaseReference usersRef = FirebaseDatabase.getInstance().getReference("users");
              usersRef.orderByChild("username")
                      .startAt(queryText)
                      .endAt(queryText+"\uf8ff");
  
              usersRef.addListenerForSingleValueEvent(new ValueEventListener() {
                  @Override
                  public void onDataChange(DataSnapshot snapshot) {
                      searchList = new ArrayList&lt;&gt;();
                      for (DataSnapshot postSnapshot: snapshot.getChildren()) {
                          User user = postSnapshot.getValue(User.class);
                          Log.d("USER: ", "" + user.getUsername());
  
                          searchList.add(user);
                      }
  
                      adapter = new UserCardAdapter(getContext(), searchList);
                      recyclerView.setAdapter(adapter);
                  }
  
                  @Override
                  public void onCancelled(DatabaseError databaseError) {
                      Log.e("onQueryTextChange: " ,databaseError.getMessage());
                  }
              });
  </code></pre>
  
  <p>However, all users are still retrieved. I have seen the usage of startAt() and endAt() supposedly work for others on other posts but I cannot manage to get it to work for me.. </p>
  
  <p>This is how the user data is stored:
  <a href="https://i.stack.imgur.com/CIRgr.png" rel="nofollow noreferrer">User Data Structure</a></p>