Interview Questions

An abstract class can have instance methods that implement a default behavior. An Interface can only declare constants and instance methods, but cannot implement default behavior and all methods are implicitly abstract. An interface has all public members and no implementation. An abstract class is a class which may have the usual flavors of class members (private, protected, etc.), but has some abstract methods.

These are accessibility modifiers. Private is the most restrictive, while public is the least restrictive. There is no real difference between protected and the default type (also known as package protected) within the context of the same package, however the protected keyword allows visibility to a derived class in a different package.

A unique constraint on a column uniquely identifies the record by a combination of one or more fields. Few unique constraint fields can have a NULL value as long as the combination of values is unique.

Example:
create table employee ( id number NOT NULL, dob DATE, professor_id NOT NULL, Name varchar(200) Constraint id_unique UNIQUE(id,dob) );

"Well, I bring nearly 5 years of customer service involvement to the group, I really have a good time for helping others, and I have also finished advanced certification courses. The combination of my work experience and knowledge make me courageous that I will be a really good fit for this role."

=> When a consumer wants to buy a certain product, he go to the website and selects the product he wants to buy. 

=> Once the product is selected, the consumer transaction is moved to the online transaction server where he places an order. 

=> The informations is exchanged over a secure channel through a private gateway to a processing network. 

=> The networked banks accept or reject the transaction.

 All this happens in just a matter of seconds. E-commerce is a very secure due to the SSL (Secure Socket Layer) technology.

Windows object is top level object in Java script. It contains several other objects such as, document, history, location, name, menu bar etc., in itself. Window object is the global object for Java script that is written at client-side.

Information pertaining to the client browser and system is returned by the navigator object of JavaScript. Navigator object is the top level object for all users.

The JVM performs three main tasks:

• Loads code

• Verifies code

• Executes code

A NSArray’s contents can not be modified once it’s been created whereas a NSMutableArray can be modified as needed, i.e items can be added/removed from it.