Why we use main at begining of program ?

Question

* Is the Java provided in this app enough to get into an entry level job or to build an app with little more efforts .
*we don't need to mention library files in java like in C++ we did ?

Answer 1

main is very important section of a code in almost every programming language and runs in the first moment of code executing. So we should use it and can't be ingnored.

Answer 2

This is like first semester of university knowledge. It is a good start.