How can I fix the Spinner style for Android 4.x placed on top of the Toolbar

I know this is late but I came accross this question when I encountered this problem myself and I found a solution in the BrowseSessionsActivity of the Google I/O 2014 app and adapted it.

Layouts

toolbar_spinner.xml

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

    <Spinner
        android:id="@+id/toolbar_spinner"
        style="@style/Widget.MyApp.HeaderBar.Spinner"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"/>

</LinearLayout>

toolbar_spinner_item_actionbar.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="200dp"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <TextView
        android:id="@android:id/text1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:drawablePadding="8dp"
        android:drawableRight="@drawable/spinner_triangle"
        android:fontFamily="sans-serif"
        android:paddingLeft="16dp"
        android:paddingRight="4dp"
        android:textColor="#ffffffff"
        android:textSize="18dp"
        android:textStyle="bold"/>

</LinearLayout>

The spinner_triangle drawable can be found here.

toolbar_spinner_item_dropdown.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="200dp"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <TextView
        android:id="@android:id/text1"
        android:layout_width="match_parent"
        android:layout_height="48dp"
        android:drawablePadding="8dp"
        android:gravity="center_vertical|start"
        android:paddingLeft="16dp"
        android:paddingRight="16dp"
        android:textColor="#ff333333"
        android:textSize="16sp"/>
        
</LinearLayout>

Styles

toolbar_spinner.xml uses the following style.

<style name="Widget.MyApp.HeaderBar.Spinner" parent="Widget.AppCompat.Light.Spinner.DropDown.ActionBar">
        <item name="android:background">?android:selectableItemBackground</item>
        <item name="android:dropDownSelector">?android:selectableItemBackground</item>
        <item name="android:divider">@null</item>
        <item name="android:overlapAnchor">true</item>
</style>

Adapter

This adapter will need to be changed to match your own needs. getTitle() returns the text for each item shown in the spinner.

private class YourObjectSpinnerAdapter extends BaseAdapter {
    private List<YourObject> mItems = new ArrayList<>();

    public void clear() {
        mItems.clear();
    }

    public void addItem(YourObject yourObject) {
        mItems.add(yourObject);
    }

    public void addItems(List<YourObject> yourObjectList) {
        mItems.addAll(yourObjectList);
    }

    @Override
    public int getCount() {
        return mItems.size();
    }

    @Override
    public Object getItem(int position) {
        return mItems.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getDropDownView(int position, View view, ViewGroup parent) {
        if (view == null || !view.getTag().toString().equals("DROPDOWN")) {
            view = getLayoutInflater().inflate(R.layout.toolbar_spinner_item_dropdown, parent, false);
            view.setTag("DROPDOWN");
        }

        TextView textView = (TextView) view.findViewById(android.R.id.text1);
        textView.setText(getTitle(position));

        return view;
    }

    @Override
    public View getView(int position, View view, ViewGroup parent) {
        if (view == null || !view.getTag().toString().equals("NON_DROPDOWN")) {
            view = getLayoutInflater().inflate(R.layout.
                    toolbar_spinner_item_actionbar, parent, false);
            view.setTag("NON_DROPDOWN");
        }
        TextView textView = (TextView) view.findViewById(android.R.id.text1);
        textView.setText(getTitle(position));
        return view;
    }

    private String getTitle(int position) {
        return position >= 0 && position < mItems.size() ? mItems.get(position).title : "";
    }
}

Adding the Spinner to Your Toolbar

Toolbar toolbar = getActionBarToolbar();

View spinnerContainer = LayoutInflater.from(this).inflate(R.layout.toolbar_spinner,
        toolbar, false);
ActionBar.LayoutParams lp = new ActionBar.LayoutParams(
        ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
toolbar.addView(spinnerContainer, lp);

YourObjectSpinnerAdapter spinnerAdapter = new YourObjectSpinnerAdapter();
spinnerAdapter.addItems(getMyObjectSpinnerData());

Spinner spinner = (Spinner) spinnerContainer.findViewById(R.id.toolbar_spinner);
spinner.setAdapter(spinnerAdapter);

Result