Adding an Icon - didn't get one on an emulator

When I downloaded the .zip file on page 42, I got an item in the res directory not listed the book. It was
’ic_launcher_foreground’ and occurred below ‘drawable’ and above ‘layout’. Could this be why the arrow image doesn’t show on the emulator?

“ic_launcher_foreground.xml” in the drawable directory is created by the IDE automatically.
Please check whether “arrow_left.png” and “arrow_right.png” are included in the drawable directory. Please also check whether the pics are used in the code.