How to redirect multiple types of users to their respective Activities?

Question

I am creating a voting app on Firebase. I have 3 types of users. So far i can successfully redirect 2 kinds of users (STUDENTS, TEACHERS) to their respective activities after they login all with the code below, MY Users so far But now i have to add another user (ADMIN) and like other users, admin too should be redirected to their own specific activity after login. I am confused as to how to modify my code for a third user.

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

                String uid = mAuth.getInstance().getCurrentUser().getUid();
                DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
                uidRef = rootRef.child("STUDENTS").child(uid);

                ValueEventListener valueEventListener = new ValueEventListener() {
                    @Override
                    public void onDataChange(com.google.firebase.database.DataSnapshot dataSnapshot) {
                        if (dataSnapshot.exists()) {
                            //start students activity
                            startActivity(new Intent(MainActivity.this, student.class));

                        } else {
                            //start teachers activity
                            startActivity(new Intent(MainActivity.this, teacher.class));
                        }
                    }

                    //
                    @Override
                    public void onCancelled(DatabaseError databaseError) 
                    {
                    }
                };


uidRef.addListenerForSingleValueEvent(valueEventListener);

            }
            else{
                Log.d("TAG", "firebaseUser is null");
            }


        }
    };

Answer 1

Using onlye if (dataSnapshot.exists()) will not solve your 3 types of user problem. Assuming that the type of the third user is 3 , a change in your database structure is needed. So your new database schema should look like this:

Firebase-root
    |
    --- users
          |
          --- uidOne
          |     |
          |     --- name: "Ed"
          |     |
          |     --- type: 1
          |
          --- uidTwo
          |     |
          |     --- name: "Tyff"
          |     |
          |     --- type: 2
          |
          --- uidOne
                |
                --- name: "Admin"
                |
                --- type: 3

Now you shoud add a listener on the uid node and check the type of the user like this:

String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference uidRef = rootRef.child("users").child(uid);
ValueEventListener valueEventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        if(dataSnapshot.child("Type").getValue(Long.class) == 1) {
            startActivity(new Intent(MainActivity.this, student.class));
        } else if (dataSnapshot.child("TYPE").getValue(Long.class) == 2) {
            startActivity(new Intent(MainActivity.this, teacher.class));
        } else if (dataSnapshot.child("TYPE").getValue(Long.class) == 3) {
            startActivity(new Intent(MainActivity.this, admin.class));
        }
    }

    @Override
    public void onCancelled(@NonNull DatabaseError databaseError) {
        Log.d(TAG, databaseError.getMessage());
    }
};
uidRef.addListenerForSingleValueEvent(valueEventListener);

Answer 2

you need another data-structure, with users and roles/admin , roles/teacher , roles/student and then check which node has the key (also compatible with security rules).

as you have it, you could simply remove the else branch and query all three nodes.

Answer 3

This is my final code using Kotlin and it is working perfectly.

mAuth.signInWithEmailAndPassword(Email, Password).addOnCompleteListener { task ->
                if (task.isSuccessful) {



                    val uid = FirebaseAuth.getInstance().currentUser!!.uid
                    val rootRef = FirebaseDatabase.getInstance().reference
                    val uidRef = rootRef.child("Users").child(uid)
                    val spin: String = userchioce.selectedItem.toString()
                val valueEventListener: ValueEventListener = object : ValueEventListener {
                    override fun onDataChange(dataSnapshot: DataSnapshot) {
                        when {
                                dataSnapshot.child("users").getValue(String::class.java) == "Admin" -> {
                                    if (spin.equals("Admin")){
                                val intent = Intent(this@Login, Admin::class.java)
                                startActivity(intent)}
                                    else{
                                        Toast.makeText(this@Login, "Select Your User-Type", Toast.LENGTH_SHORT)
                                            .show()
                                    }
                            }

                            dataSnapshot.child("users").getValue(String::class.java) == "Lecturer" -> {
                                if (spin.equals("Lecturer")) {
                                    val intent = Intent(this@Login, Lecturer::class.java)
                                    startActivity(intent)
                                }else{
                                    Toast.makeText(this@Login, "Select Your User-Type", Toast.LENGTH_SHORT)
                                        .show()
                                }
                            }
                            dataSnapshot.child("users").getValue(String::class.java) == "Parent" -> {
                                if (spin.equals("Parent")) {
                                    val intent = Intent(this@Login, Parent::class.java)
                                    startActivity(intent)
                                }else{
                                    Toast.makeText(this@Login, "Select Your User-Type", Toast.LENGTH_SHORT)
                                        .show()
                                }
                            }
                            dataSnapshot.child("users").getValue(String::class.java) == "Student" -> {
                                if (spin.equals("Student")) {
                                    val intent = Intent(this@Login, Student::class.java)
                                    startActivity(intent)
                                }else{
                                    Toast.makeText(this@Login, "Select Your User-Type", Toast.LENGTH_SHORT)
                                        .show()
                                }
                            }
                        }
                    }

                    override fun onCancelled(databaseError: DatabaseError) {
                        Log.d(TAG, databaseError.message)
                    }
                }
                uidRef.addListenerForSingleValueEvent(valueEventListener)
                    progressDialog.dismiss()
                }