I have a Spinner which background is white

The problem is there's no dropdown arrow, so users wouldn't easily recognize that this field is a spinner/dropdown.

Here's my code:

MainActivity.java

String[] arrPaymentTypes = {"Cash", "Bank Transfer", "Wallet"};
ArrayAdapter<String> spnPaymentTypeAdapter = new ArrayAdapter<String>(this, R.layout.spinner_item, arrPaymentTypes);
spnPaymentTypeAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spnPaymentType.setAdapter(spnPaymentTypeAdapter);

spinner_item.xml

<?xml version="1.0" encoding="utf-8"?>
<TextView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textSize="14sp"
    android:gravity="left"
    android:textColor="@color/black"
    android:padding="1dip"
/>

activity_main.xml

<Spinner
        android:id="@+id/spnPaymentType"
        style="@style/mySpinnerItemStyle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/lblPaymentType
        android:popupBackground="@color/white" />

/values/styles.xml

<style name="mySpinnerItemStyle" parent="@android:style/Widget.Holo.DropDownItem.Spinner">
    <item name="android:textColor">@android:color/white</item>
</style>        

I tried adjusting a few Spinner proprties like backgroundTint and doesn't work. What's the proper solution?