从 View.GONE 状态到 View.VISIBLE 的 setVisibility 无法正常工作

Question

I have a real strange problem and I don't know how to solve it. I have a View inside a LinearLayout with attribute android:visibility="gone" this is the layout file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@color/bg"
    android:orientation="vertical">

    <TextView
        android:id="@+id/titleTextView"
        android:gravity="end"
        android:text="dfgdfg"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@android:color/transparent"
        android:paddingTop="5dp"
        android:paddingBottom="5dp"/>

    <View
        android:layout_width="match_parent"
        android:layout_height="8dp"
        android:background="@drawable/shadow"
        android:id="@+id/preLollipopShadow"
        android:visibility="gone"/>

</LinearLayout>

when I want to change visibility of view with preLollipopShadow I use this code

if (newPosition == StickyHeaderLayoutManager.HeaderPosition.STICKY) {
                        ((ViewGroup)header).getChildAt(1).setVisibility(View.VISIBLE);

                    }
                    else
                    {
                        ((ViewGroup)header).getChildAt(1).setVisibility(View.GONE);

                    }

it is not working as I expect , I want that shadow be visible on sticky mode and be gone otherwise .

how can I achieve that ?

UPDATE 1 : When I start with visibility "invisible" and switch to "visible" and back it is working but not with starting state of "gone" on my preLollipopShadow view.

UPDATE 2 : The view is inside a RecyclerView , Does not updating view visibility somehow related to being nested into a RecyclerView ?

Answer 1

The View you want to hide and show has an id of preLollipopShadow attached to it. Its easy to find the view by its id.

parentView.findViewById(R.id.preLollipopShadow);

or

findViewById(R.id.preLollipopShadow);

if you want to reference the view from an activity.