Firebase Realtime database not updating children

Question

I use the realtime database to store some values.
I want to update these values via a button-click.
I tried using setValue and updateChildren but both did not work. I get no errors and the app does not crash. The updating works when I restart the app but only once. After the first time, the values get added as new values.

 public void PostToDatabase(String databasestring, ArrayList<Integer> arrayList)
{
    database = FirebaseDatabase.getInstance();
    myRef = database.getReference(databasestring);

    Map<String,Object> postvalues =  new HashMap<>();

    for (int i = 0;i<arrayList.size();i++) {
        postvalues.put(myRef.child(String.valueOf(i)).getKey(),arrayList.get(i));
    }
    myRef.updateChildren(postvalues);
}

seems like "i" does not reset after each click.

*****EDIT*****

public void PostToDatabase(String databasestring, ArrayList<Integer> arrayList)
{

    database = FirebaseDatabase.getInstance();
    myRef = database.getReference(databasestring);

    Map<String, Object> childUpdates = new HashMap<>();

    for (int i = 0;i<arrayList.size();i++) {
        MyPacket myPacket = new MyPacket(arrayList.get(i).toString(), false, true, false);
        Map<String, Object> postValues = myPacket.toMap();

        childUpdates.put(myRef.child("Numbers").push().getKey(),postValues);
    }
    myRef.updateChildren(childUpdates).addOnCompleteListener(new OnCompleteListener<Void>() {
        @Override
        public void onComplete(@NonNull Task<Void> task) {
            if(task.isSuccessful())
            {
                Log.d(TAG,"onComplete");
            }
            else
            {
                Log.e(TAG,"onComplete", task.getException());
            }
        }
    });
}

The call of the Funktion

B_weiter.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            for (int index1 = 0; index1 < (tableLayout).getChildCount(); ++index1) {
                TableRow upperChild = (TableRow) (tableLayout).getChildAt(index1);
                for (int index2 = 0; index2 < ((ViewGroup) upperChild).getChildCount(); ++index2) {
                    EditText lowerChild = (EditText) ((ViewGroup) upperChild).getChildAt(index2);
                    myNumbers.add(Integer.parseInt(lowerChild.getText().toString()));
                }

            }
            ((WaeschelisteActivity)getActivity()).PostToDatabase("Numbers",myNumbers);
            myNumbers.clear();
        }


    });

I created a class for my values but it still does not work. Same Problem. I hope you guys can help me.

Answer 1

public void PostToDatabase(String databasestring, ArrayList<Integer> arrayList)
{

    database = FirebaseDatabase.getInstance();
    myRef = database.getReference(databasestring);

    Map<String, Object> childUpdates = new HashMap<>();

    for (int i = 0;i<arrayList.size();i++) {
        MyPacket myPacket = new MyPacket(arrayList.get(i).toString(), false, true, false);
        Map<String, Object> postValues = myPacket.toMap();

        childUpdates.put("/user-posts/" + i ,postValues);
    }
    myRef.updateChildren(childUpdates);
    childUpdates.clear();

}

i got rid of the key and added "/user-posts/" to childUpdates it works !!! Thanks for your help!