The Output line

Just essential statement in the program is

"System.out.println("Welcome to the world of Java programming");

This is same to the printf() statement of C.   Because Java is a true Object oriented programming language every method is an elements of an object.  The println function is a member of the class out object that is a static data member of System class.  This line prints the string as

Welcome to the world of Java Programming on the screen.