Custom arrows without image: Android
Can be done easily using paths:
<?xml version="1.0" encoding="utf-8"?>
<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:width="32dp"
android:height="24dp"
android:viewportWidth="32.0"
android:viewportHeight="24.0">
<path android:fillColor="#e4e4e8"
android:pathData="M0 0 h32 l-16 24 Z"/>
</vector>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="▲"/>
or
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="▼"/>
You can get here more options.