when I manually change value in firebase database I create more items in listview instead of updating value in listview

Question

I have No idea what\'s going wrong in my code Please Help Me. Just Trying To Retrieve data to list view.

My MainActivity.java

public class MainActivity e         


        

Answer 1

When you update a value in your database, it will trigger your

public void onDataChange(@NonNull DataSnapshot dataSnapshot) {...

Again, and that will fetch for all childrens (included the updated one) and will be placed inside the list again this will duplicate the items since inside your onDataChange you have a for loop that will loop throught all the childrens again and will add them again to the current populated list.

What you need to do, is to clear the list when is fetched again

ref.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            list.clear();
            for (DataSnapshot ds: dataSnapshot.getChildren()){

                user = ds.getValue(User.class);
                list.add(user.getName().toString()+user.getEmail().toString());

            }
            listView.setAdapter(adapter);

        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });

Another way you can do it is to use updateChildren() with a map, this will just update the item you are updating in your database