3i Infotech Papers: Sample Questions 1196 - 1198 of 1245

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Question number: 1196

» Languages » Java

Essay Question▾

Describe in Detail

What are abstract classes?


  • Abstract classes are those for which instances can’t be created.

  • Class declared abstract may or may not include abstract methods.

  • An abstract method is declared without an implementation

  • In object-oriented programming (OOP), classes represent objects in the domain of the problem.

  • Classes are collections of attributes and behaviours based on previously-defined classes.

  • Programmers use inheritance to derive the specific implementation of abstract classes.

  • Classes derived from abstract classes are called derived classes.

  • Principle applied many times in succession results in a hierarchy of classes.

Question number: 1197

» Languages » Java

Short Answer Question▾

Write in Short

Which class begins Java class hierarchy?


Declare java class hierarchy

Declare Java Class Hierarchy

Declare java class hierarchy

  • Object class begins java class hierarchy.

  • Defines java. lang package- defines and implements behaviour common to all classes.

  • Its methods are available to all java classes.

  • Acts as a root of inheritance hierarchy in any java program.

Question number: 1198

» Languages » C & C Plus Plus

Short Answer Question▾

Write in Short

What is RTTI?


  • Run time type information is a mechanism that allows the type of an object to determine during program execution.

  • Added to the C++ language because many class libraries implementing this functionality resulting in incompatibilities between libraries.

  • Available only for classes, which are polymorphic, which means they have at least one virtual method.