Determine if an item is mapped to a RecyclerView

Question

I built a basic interface consisting of a CardView list inside a RecyclerView. When a map is added, I need to know if it is visible on the screen or not.

I am trying to trick this using the layoutListVisibleItemPosition () method, but it seems to return the result one element less than expected. For example, if I have 1 map that is visible findLastVisibleItemPosition () returns -1 (where I expect the index of the visible map to be 0).

My simplified core methods are as follows:

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    items = new ArrayList<>();

    RecyclerView recycList = (RecyclerView) findViewById(R.id.rv);
    recycList.setHasFixedSize(true);
    llm = new LinearLayoutManager(this);
    llm.setOrientation(LinearLayoutManager.VERTICAL);
    recycList.setLayoutManager(llm);
    recycList.addOnChildAttachStateChangeListener(new ChildAttachListener(llm));
    adapter = new RecycAdapter(items);
    recycList.setAdapter(adapter);
}

private void addItem(){
    items.add(new Item());
    adapter.notifyDataSetChanged();
}

private class ChildAttachListener implements OnChildAttachStateChangeListener{
    LinearLayoutManager llm;

    public ChildAttachListener(LinearLayoutManager llm){
        super();
        this.llm = llm;
    }

    @Override
    public void onChildViewAttachedToWindow(View view) {

        System.out.println("Items size = "+items.size() + ", Last Visible Item = "+llm.findLastVisibleItemPosition());
    }

    @Override
    public void onChildViewDetachedFromWindow(View view) {

    }
}

Return on adding the first item:

Items size = 1, Last Visible Item = -1

Return on adding the second item:

Items size = 2, Last Visible Item = 0
Items size = 2, Last Visible Item = 0

Return on adding the third item:

Items size = 3, Last Visible Item = 0
Items size = 3, Last Visible Item = 1
Items size = 3, Last Visible Item = 1

In all cases, all elements are visible (7 visible elements can be displayed on the screen).

- findLastVisibleItemPosition() , , ?

EDIT: , - , , ( addItem()). addItem() .

Answer 1

, , , findLastVisibleItemPosition :

@Override
public void onChildViewAttachedToWindow(View view) {

    Handler handler = new Handler();
        handler.post(new Runnable() {
            @Override
            public void run() {

                System.out.println(llm.findLastVisibleItemPosition());
            }
        });
}