Interview Questions - Core Java

57.
What is Externalizable?
Externalizable is an Interface that extends Serializable Interface. And sends data into Streams in Compressed Format. It has two methods, writeExternal(ObjectOuput out) and readExternal(ObjectInput in)

58.
What modifiers are allowed for methods in an Interface?
Only public and abstract modifiers are allowed for methods in interfaces.

59.
What is a local, member and a class variable?

Variables declared within a method are "local" variables.

Variables declared within the class i.e not within any methods are "member" variables (global variables).

Variables declared within the class i.e not within any methods and are defined as "static" are class variables.


60.
What is an abstract method?
An abstract method is a method whose implementation is deferred to a subclass.