How to get random documents from Firestore and display them in different TextViews?

In my app the user should be able to choose from 3 different categories (out of 8) which are randomly generated. For this I used the approach described here.

I don't know how to use this approach to use the retrieved documents to insert them into the TextViews in my Category Activity. I created a category class to store the retrieved documents from Firestore but I also don't know if that is even the right approach. I would very much appreciate every tip!

Here is my Category Activity where the 3 documents get retrieved and in the end should be displayed in the TextViews:

@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.activity_category_selection, container, false);
tvCategory1 = view.findViewById(R.id.text_view_category_1);
tvCategory2 = view.findViewById(R.id.text_view_category_2);
tvCategory3 = view.findViewById(R.id.text_view_category_3);
textViewCategoryRound = view.findViewById(R.id.text_view_category_round);
imageCategory1 = view.findViewById(R.id.image_category_1);
imageCategory2 = view.findViewById(R.id.image_category_2);
imageCategory3 = view.findViewById(R.id.image_category_3);
categoryCollectionRef.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
@Override
public void onComplete(@NonNull Task<QuerySnapshot> task) {
if (task.isSuccessful()) {
List<Category> categoryList = new ArrayList<>();
for (DocumentSnapshot document : task.getResult()) {
Category category = document.toObject(Category.class);
categoryList.add(category);
}
int categoryListSize = categoryList.size();
List<Category> randomCategoryList = new ArrayList<>();
for (int i = 0; i < categoryListSize; i++) {
Category randomCategory = categoryList.get(new Random().nextInt(categoryListSize));
if (!randomCategoryList.contains(randomCategory)) {
randomCategoryList.add(randomCategory);
if (randomCategoryList.size() == 3) {
break;
}
} else {
Log.d(TAG, "Error getting documents: ", task.getException());
}
}
}
}
});
return view;
}
}

Here is the category class where I hope I store the documents correctly:

public class Category {
public String category_name;
public String picture_id;
public Category (){
}
public String getPicture_id() {
return picture_id;
}
public void setPicture_id(String picture_id) {
this.picture_id = picture_id;
}
public String getCategory_name() {
return category_name;
}
public void setCategory_name(String category_name) {
this.category_name = category_name;
}
public Category(String category_name){
this.category_name = category_name;
}
}

Here is the way I structured my Category collection (there are 8 documents/categories):

Hi i can suggest easy way.

 List<Category> categoryList =null;
categoryCollectionRef.get().addOnCompleteListener(new 
OnCompleteListener<QuerySnapshot>() {
@Override
public void onComplete(@NonNull Task<QuerySnapshot> task) {
if (task.isSuccessful()) {
categoryList = new ArrayList<>();
for (DocumentSnapshot document : task.getResult()) {
Category category = document.toObject(Category.class);
categoryList.add(category);
}
}
}
}
});
testButtonClickListener....{
Collections.shuffle(categoryList);
showShuffledList();
}
public void showShuffledList(){
textView1.setText(categoryList.get(0).getCategoryName())
textView2.setText(categoryList.get(1).getCategoryName())
textView3.setText(categoryList.get(2).getCategoryName())
}

> Of course you should add null check all steps and configure more way.

You can do 3 things:

1. when saving the docs name them with an incremental number at the end, then generate 3 random numbers in range and fetch the docs ending in those numbers.

2. add a field in all docs that holds a unique number and follow similar approach to the above but using a query on those fields.

3. create a special doc that has the names of all other docs in an array. Then fetch 3 doc names from the array based on the generated random numbers.

There might be other ways too, but those are the approaches that first come to my mind.