Technical Interview Questions and Answers :: Syntel Inc.

No, an interface can't be instantiated. Interface is similar to class. Interface can only have abstract methods. A class can implement an interface.

A virtual function, equated to zero is called a pure virtual function. It is a function declared in a base class that has no definition relative to the base class. A class containing such pure function is called an abstract class.
It objectives are
• Provide some traits to the derived classes.
• To create a base pointer required for achieving run time polymorphism.

Constructor are similar methods that are called when an instance of the class is created. The constructor doesn't explicitly returns a value but it does constructs something that as an instance can be used for that class.

'super' keyword in Java is a reference variable which is used to access parent class objects.

'this' keyword is a reference variable which is used to access current objects.

'static' is a keyword available in Java. The variable that is declared as static, is called as class variable. All instances share the same copy of the variable.

Eg.: static int y=1;

Iterator allows to traverse the collection and also it has methods which enables to obatin or remove elements. ListIterator adds the feature of traversing the list bi-directionally, also modify the elememts.

Eg.: Iterator itr = al.iterator();

       while(itr.hasNext()) {}

List is subinterface of collection interface 

List is objects can be stored in sequencelly order 

List objects can be stored in index or access by its index

List is preserve the order of insertion.

List duplicate objects can be stored and also null insertion is allowed.

list is 3 implemention classes

1.ArrayList Class

2.LinkedList Class

3.Vector Class

arrays store only primitive type values and arraylist store primitive type

Yes, Consider a category table in a e-commerce web site.
Category_Id, Category_Name, Parent_Category_ID. In this table all the parent categories are also categories. When we create a self join category id will be treated as foreign key to the same table.

Nnormalization is step by step process of spiliting the bigger table into smaller table without changing any functionality. This wil improve the performance.

There are some way to normalize table 

A. 1nf

B.2nf

C.3nf