如何将两个集合添加到firestore中的集合android studio中

Question

我正在尝试使用android studio中的Firestore制作一个课程添加系统。

当用户添加一个课程时，它将被添加到Fi还原中，并且在该课程集合中会有一个学生和教师集合。

但我不知道怎么做。

如果我为学生和教师集合编写代码，它会添加两个不同的集合，但我希望在一个课程集合中有两个集合，学生和教师。

我该怎么做呢？

我分享我写的代码。

添加课程类

private ActivityDersEkleBinding binding;
private FirebaseFirestore mFirestore;
private String txt_lesson;
private   LinkedHashMap<String,String> linkedHashMap;
private int i=1;
private CollectionReference Courses;

public void init(){
    linkedHashMap = new LinkedHashMap<>();
    mFirestore = FirebaseFirestore.getInstance();
    Courses = mFirestore.collection("Courses");
    Ders_EKLE();
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    binding = ActivityDersEkleBinding.inflate(getLayoutInflater());
    View view = binding.getRoot();
    setContentView(view);
    init();
}

private void Ders_EKLE(){

    //Ders ekleme tam olmadı. Tekrar bakılacak.

    binding.btnEkleDers.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            txt_lesson = binding.isimDers.getText().toString();

     //Show alertdialog if the user has entered an empty lesson 

            if(txt_ders.equals("")){
                AlertDialog.Builder builder = new AlertDialog.Builder(DersEkleActivity.this);
                builder.setTitle("WARNING!");
                builder.setMessage("you cant empty value !");
                builder.setIcon(R.drawable.warningicon);
                builder.setPositiveButton("Tamam", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {

                    }
                });
                builder.show();
            }
            else {

         //If a lesson has been entered, add it to the firestore.

                linkedHashMap.put("lesson"+i,txt_lesson); 


                int j=1;
                Courses.document("KDXnJKKno1D2xtG9G6UE").collection("Lessons")
                        .document()
                        .collection(txt_lesson)
                        .document()
                        .collection("Student")
                        .add(new DersEklePerson())
                        .addOnSuccessListener(new OnSuccessListener<DocumentReference>() {
                            @Override
                            public void onSuccess(@NonNull DocumentReference documentReference) {
                                Toast.makeText(DersEkleActivity.this,"Ders başarıyla eklendi.",Toast.LENGTH_LONG).show();
                            }
                        }).addOnFailureListener(new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception e) {

                    }
                });





            }

        }
    });

}