What is built in Java class?

The main () function as a built-in function : The compilers of most of the programming languages are so designed that the main () function constitutes the entry point of the program execution.

In Java, all classes (built-in or user-defined) are (implicitly) subclasses of Object . Using an array of Object in the List class allows any kind of Object (an instance of any class) to be stored in the list. However, primitive types (int, char, etc) cannot be stored in the list.

ii) Java Number Methods