如何在 android studio 中获取我新创建的文档的 id？

一直试图从我的新产品哈希图中获取 id 以发送到另一个活动，但从 logD 我一直只获取集合名称，例如。产品而不是 eg.Jfchd1jff3k<- 从 Firestore 随机生成的 id 有没有办法在创建后立即获得它？

enter code here

公共类 newProduct 扩展 AppCompatActivity {

private Button  addProduct;
private EditText productName, productDescription, productPrice;
private Spinner category;
FirebaseAuth fAuth;
FirebaseFirestore fStore;
FirebaseUser fUser;
StorageReference storageReference;
private String userID;



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_new_product);

    fAuth = FirebaseAuth.getInstance();
    fUser = fAuth.getCurrentUser();
    fStore = FirebaseFirestore.getInstance();
    storageReference = FirebaseStorage.getInstance().getReference();

    addProduct = findViewById(R.id.btn_addProduct);
    productName = findViewById(R.id.et_productName);
    productDescription = findViewById(R.id.et_productDescription);
    productPrice = findViewById(R.id.et_productPrice);
    category = findViewById(R.id.catSpinner);



    String[] arraySpinner = new String[]{
            "Yoga", "Lifting", "Water Sports", "Pilates", "Other"
    };
    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_spinner_item, arraySpinner);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    category.setAdapter(adapter);


    addProduct.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            saveProduct();

        }
    });

}


private void saveProduct(){
    userID = fAuth.getCurrentUser().getUid();
    DocumentReference df = fStore.collection("Users").document(userID);
    DocumentReference df2 = fStore.collection("Instructors").document(userID);
    String name = productName.getText().toString();
    String description = productDescription.getText().toString();
    String price = productPrice.getText().toString();
    String cat = category.getSelectedItem().toString();


    if(name.trim().isEmpty() || description.trim().isEmpty() || price.trim().isEmpty()){
        Toast.makeText(this,"Fields Cannot Be Empty", Toast.LENGTH_SHORT).show();
        return;
    }
    df.get().addOnSuccessListener(new OnSuccessListener<DocumentSnapshot>() {
        @Override
        public void onSuccess(DocumentSnapshot documentSnapshot) {
            if(documentSnapshot.getString("isuser") != null){

                String userContact = documentSnapshot.getString("Mobile");

                CollectionReference productsRef = FirebaseFirestore.getInstance()
                        .collection("Products");
                Map<String, Object> product = new HashMap<>();
                product.put("userID", userID);
                product.put("productName", name);
                product.put("productDescription", description);
                product.put("price", price);
                product.put("category", cat);
                product.put("contact", userContact);
                productsRef.add(product);

                //this is the part where i try to get the id
                String id= productsRef.getId();

                Intent intent = new Intent(getApplicationContext(), saveProductImage.class);
                intent.putExtra("productID", id);
                startActivity(intent);

                finish();

            }else{
                df2.get().addOnSuccessListener(new OnSuccessListener<DocumentSnapshot>() {
                    @Override
                    public void onSuccess(DocumentSnapshot documentSnapshot) {
                        if(documentSnapshot.getString("isinstructor") !=null){
                            String userContact = documentSnapshot.getString("Mobile");

                            CollectionReference productsRef = FirebaseFirestore.getInstance()
                                    .collection("Products");
                            Map<String, Object> product = new HashMap<>();
                            product.put("userID", userID);
                            product.put("productName", name);
                            product.put("productDescription", description);
                            product.put("price", price);
                            product.put("category", cat);
                            product.put("contact", userContact);
                            productsRef.add(product);

                            finish();
                        }
                    }
                });
            }
        }
    });
}

}