friend function
friend function of a class is defined outside that class' scope but it has the right to access all private and protected members of the class. Even though the prototypes for friend functions appear in the class definition, friends are not member functions.
const keyword in java
A constant is a variable whose value cannot change once it has been assigned. Java doesn't have built-in support for constants, but the variable modifiers static and final can be used to effectively create one. Constants can make your program more easily read and understood by others.
final keyword in java
The final keyword in java is used to restrict the user. The java final keyword can be used in many context. Final can be:
variable
method
class
The final keyword can be applied with the variables, a final variable that have no value it is called blank final variable or uninitialized final variable. It can be initialized in the constructor only. The blank final variable can be static also which will be initialized in the static block only
