Confluxsys Interview Questions and Answers

Polymorphism in Java allows objects of different classes to be treated as objects of a common superclass.

• Polymorphism allows methods to be overridden in a subclass that is already defined in its superclass.

• It enables a single interface to be used for different data types.

• Examples include method overriding and method overloading.

Static member class is a nested class that belongs to the outer class, but does not have access to non-static members of the outer class.

• Static member class is declared using the 'static' keyword within the outer class.

• It can access static members of the outer class directly.

• Static member class can be instantiated without an instance of the outer class.

• Example: class Outer { static class Inner { } }

• Example: Outer.Inner

Non static inner class is a class defined within another class that is not declared as static.

• Non static inner class has access to instance variables and methods of the outer class.

• It can be instantiated only within an instance of the outer class.

• Example: public class Outer { class Inner { } }

• Example: Outer outer = new Outer(); Outer.Inner inner = outer.new Inner();

Anonymous classes are inner classes without a name, used for one-time implementation of interfaces or classes.

• Anonymous class can be used to implement interfaces or extend classes on the fly.

• They are defined and instantiated at the same time.

• Syntax: new InterfaceName() { // implementation }

• Example: Runnable r = new Runnable() { public void run() { // implementation } };