Page 475 - Computer science 868 Class 12
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5.  ………………… in Java refers to the same object having multiple forms and attributes.
                    6.  ………………… methods are the methods with no method body.

                   Answers
                     1.  transitive      2.  interface     3.  public    4.  hybrid   5.   Polymorphism        6.  abstract

                 C.  Answer the following questions:
                    1.  Differentiate between method overloading and method overriding.
                   Ans.
                                       Method overloading                                Method overriding
                       a. Methods have the same names but different signatures. a. Methods have the same names and same signature.
                       b. It can be implemented in same class or derived class.  b.  Overriding methods  belong  to the base and  derived
                                                                           classes.
                       c.  Function call and function signature are linked at compile  c.  Function  call  and  function  signature  are  linked  at  run
                         time.                                            time.
                    2.  Differentiate between interface and abstract class.
                   Ans.
                                            Interface                                      Abstract class
                       a. It has abstract methods only.                  a. It has both abstract and concrete methods.
                       b. A class can implement multiple interface.      b. A class can inherit only a single abstract class.
                       c. Interface variables are declared as public static final.  c.  Abstract class variables can contain any access modifiers.
                    3.  Differentiate between the keywords extends and implements.
                   Ans.
                                            Extends                                        Implements
                       a. The extends keyword is used to inherit a class.  a. The implements keyword is used to define interface.
                       b. A class can extend only a single class.        b. A class can implement multiple interfaces.
                       c.  A  subclass that extends a super class can override some  c. A class must implement all the methods from interfaces.
                         of it’s methods.


                    4.  A super class Godown has been defined to store the details of the stock of a retail store. Define a subclass Update to store the
                       details of the items purchased with the new rate and update the stock. Some of the members of both the classes are given
                       below.                                                               [ISC Specimen Paper 2022 Semester II]
                        Class name                            :  Godown
                        Data Members/instance variables
                        item                                  :   to store the name of the item
                        qty                                   :   to store the quantity of an item in stock
                        rate                                  :   to store the unit price of an item
                        amt                                   :  to store the net value of the item in stock
                        Member Functions/methods
                        Godown( …)                            :  parameterised constructor to assign values to the data members
                        void display( )                       :   to display the stock details
                        Class name                            :   Update
                        Data Members/instance variables
                        pur_qty                               :   to store the purchase quantity
                        pur_rate                              :  to store the unit price of the purchased item
                        Member Functions/methods
                        Update(…)                             :  parameterised constructor to assign  values  to the data members of
                                                                 both the classes





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