id within drawable within layout

Question

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Edit: My question is different because the answer referenced is not trying to access and modify the drawable (which is what my question is about), but it is just replacing the drawable.

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I'm trying to change the color of a shape within a drawable within a layout within a button.

My question is: How do I access the id for the shape element programmatically?

Here is the drawable that contains the shape within a selector (It is called 'ic_mf_account_icon.xml'):

<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <item>
        <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
            <item android:id="@+id/accountShape">
                <shape xmlns:android="http://schemas.android.com/apk/res/android"
                    android:shape="oval">
                    <solid android:color="@color/btn_bg_normal" />
                    <corners android:radius="@dimen/programmatic_btn_corner_radius" />

                </shape>

            </item>
            <item android:right="10dp" android:left="10dp" android:top="10dp" android:bottom="10dp" android:drawable="@drawable/ic_server"/>

        </layer-list>
    </item>
</selector>

Here is the layout that contains the drawable I just listed (The drawable is referenced in the Button at the top):

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
style="@style/FilesListItem" >

<FrameLayout style="@style/FilesListContent" >

    <Button
        android:id="@+id/icon"
        android:layout_width="36dip"
        android:layout_height="36dip"
        android:background="@drawable/ic_mf_account_icon" />

    <include layout="@layout/files_list_item_overlay" />
</FrameLayout>

<LinearLayout
    android:layout_width="0dip"
    android:layout_height="wrap_content"
    android:layout_gravity="center_vertical"
    android:layout_weight="1"
    android:gravity="center_vertical"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ellipsize="end"
        android:paddingLeft="10dip"
        android:singleLine="true" />
</LinearLayout>

<ImageButton
    android:id="@+id/info"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="top|right"
    android:background="@null"
    android:padding="@dimen/info_icon_padding"
    android:src="@drawable/ic_info_grey_normal" />

</LinearLayout>

Here is where I'm trying to access the drawable. I can access the initial layout, but when I try to stem from there and access the drawable I get a null reference -- To note, This is within a fragments 'onCreateView(...)' function if that matters:

    public View onCreateView(final LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_account_list, container, false);
        FindView find = FindView.inView(view);
//        AbsListView absListView = find.absList(android.R.id.list);
        AbsListView absListView = view.findViewById(android.R.id.list);

        absListView.setAdapter(arrayAdapter = new BaseListAdapter<Account>(getActivity(), accounts) {
            @Override
            public View getView(int position, View convertView, ViewGroup parent) {
                if (convertView == null) {
                    convertView = layoutInflater.inflate(R.layout.fragment_account_list_item, parent, false);


                    View layoutView = convertView.findViewById(R.id.icon);
                    View drawableView = layoutView.findViewById(R.id.accountShape);
                    Drawable drawableBackground = drawableView.getBackground();
                    // From here I will endeavor to modify the drawables shape background.

Here is the code within the code just mentioned where I am trying to access the drawable from within the layout:

View layoutView = convertView.findViewById(R.id.icon);
View drawableView = layoutView.findViewById(R.id.accountShape);
Drawable drawableBackground = drawableView.getBackground();