I downloaded some free icons and created a notification. At first I thought something was broken but then I realized that the icon I had used was in the same color as the background.
The pack I downloaded included several versions like “holo_dark” and “holo_light”. I assume that this has something to do with theming in different android versions or user customizable settings.
What is the intended way to figure out which icon to use in such cases?
The icons are specific to the theme that you will be using in your android application. You have to identify the theme in your application and then use the specific set of icons for your theme.
For more clarity you can refer the Android Asset Studio ActionBar and Tab Icon Generator and see the difference in icons generated for different themes.
Also this article will be very useful in understanding how Styles and Themes work in Android.