Why doesn't the color change in main activity?

Question

Java

Good!
I can not understand why the background color in the activity does not change? This activity is the main one, in other activities it changes without problems.

Answer 1

make the layout_hieght and layout_width attributes equal to math_parent . Because you have the wrap_content attributes set, your RelativeLayout does not take up all the available space. Or insert some child element into the RelativeLayout, in which these parameters will be equal to math_parent

<RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">