Making Apps.

Is it very difficult to make Apps for Android as example, or is it very easy, i wanna start this as my hobby.

it's super easy if you already know java, if you don't start there (download jstudio and hangout on code.org or sumthin) after that you can download android studio. there a loads of tutorials online and the program is amazing. If you want to make games start off downloading unreal engine. it's a very diverse engine and can push out amazing mobile games. good luck!

The difficulty depends on the scope of the project but as you learn everything will be easy. Use android studio if your pc can support the requirements or eclipse but I suggest android studio.