Trying to copy data from one place in firebase to another. Getting database path error
<p>Here is my current database structure:</p>

<pre><code>{
 "Classes" : {
    "aa" : {
        "classID" : "aa",
        "className" : "aa",
        "days" : [ "tuesday", "thursday" ],
        "startTime" : "1010",
        "teacherID" : "XiYeok0F0zMtZT7qRVeEXRilWEs1"
    },
    "test101" : {
       "classID" : "test101",
       "className" : "testing classes",
       "days" : [ "monday", "wednesday", "friday" ],
       "gpsLocation" : "999",
       "startTime" : "1010",
       "teacherID" : "y4cLhvIGvkcErHPTAXsglb0rXcl1"
    }
},
 "Users" : {
   "jYi10gDlWEcoLgJ6xgRHQ2qeAxI2" : {
     "classList" : [ {
         "className" : "Ignore me"} ],
     "fname" : "Rick",
     "id" : "jYi10gDlWEcoLgJ6xgRHQ2qeAxI2",
     "lname" : "Ross"
},
   "reg6pCXft3Uvlg87VxXFnEBQ6Lt1" : {
      "classList" : [ {
      "className" : "Ignore me"} ],
      "fname" : "name",
      "id" : "reg6pCXft3Uvlg87VxXFnEBQ6Lt1",
      "lname" : "name"
},
  "y4cLhvIGvkcErHPTAXsglb0rXcl1" : {
      "classList" : [ {
      "className" : "Ignore me"} ],
      "fname" : "name",
      "id" : "y4cLhvIGvkcErHPTAXsglb0rXcl1",
      "lname" : "name"
}
}
}
</code></pre>

<p>What I am trying to do is copy the user that is open in the picture, and paste that information with the same formatting into the class "test101" but in a node called roster. </p>

<p>I have seen plenty with value change listeners but I dont see how that will apply here if i am not changing the values but just need to read them into code and then put them elsewhere. </p>

<p>here is my code so far:</p>

<pre><code>import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.Query;

public class Join_Class extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_join_class);
    final FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
    final DatabaseReference fbRef = FirebaseDatabase.getInstance().getReference();

    final EditText etClassID = (EditText) findViewById(R.id.etClassID);
    Button joinBut  = (Button) findViewById(R.id.bJoin);
    final String userID = fbRef.child("Users").child(user.getUid()).getKey();


    joinBut.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View v){
            final String classID = etClassID.getText().toString().trim();
                if(fbRef.child("Classes").child(classID).getKey() == classID){
                    //get user id node information
                    //put into arraylist in class specified
                    //not asking you to write this for me, maybe what to use 
                    //for the task
                }
            sendTo(Main__Menu.class);
        }
    });

}

private void sendTo(Class s){
    Intent intent = new Intent(this, s);
    startActivity(intent);
}
}
</code></pre>