How to update an array of objects in Firestore?

What if we have two John in array so both values gets updated?

I have seperate arrays for each document for my collection... So how do I update any one object from that Arrays ??? I have edit and delete function.... delete function is working but edit function is not working... When I try to edit one object nothing happens in firestore..

Kudos to you.
I solved an array problem.

How do I put this code on Android Java , its complaining about OnCompleteListener , not requiring DocumentSnapshot

ttached screenshot document model

What if I have 100+ documents in collection("users") and all have "friends" array field , is there way I can specific target one document?

Question, if we remove an element in the array, perform the changes we need and re-add to the array, then won't the array be added at the end of the array and not at the original index as an update should be? For example: You delete the array at index 0 in an array of three elements, and then when you add it again with new data using array union, it gets added to array and now has index 2?