Why is getResources().getColor(int) deprecated?

The document says:

This method was deprecated in API level 23. Use getColor(int, Theme) instead.

And many posts point to the ContextCompat.getColor(Context, int) method as a replacement.

Also the document explains the Theme parameter:

theme Resources.Theme: The theme used to style the color attributes, may be null.

Can you explain how can the theme affects the color?

Solution

Some complex colors like android.content.res.GradientColor (which are used inside a VectorDrawable) need a Theme in order to inflate the gradient, since you could have a definition like:

<gradient xmlns:android="http://schemas.android.com/apk/res/android">
   <android:startColor="?android:attr/colorPrimary"/>
   <android:endColor="?android:attr/colorControlActivated"/>
   <android:type="linear"/>
 </gradient>