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02                     ELEMENTARY CONCEPT OF




                                                                    OBJECTS AND CLASSES














                           Learning Objectives



                     2.1 Class in Java              2.2 Object                    2.3 Properties of Class and Object





                 Object-oriented programming allows us to develop programs by using the concept of class and object. The basic
                 structure of java programs is encapsulated in a class. A class consists of characteristics and behaviours which are used
                 to create objects.
                 For example, if 'computer' is a class then Supercomputer, Mainframe computer, Minicomputer, Desktop and Laptop
                 are the objects which can use the properties of the computer class.
                                                                                            class name: COMPUTER
                 Let us take COMPUTER as a class. It has different characteristics Speed, Storage,    Characteristics:
                 Portability, etc. where one of its behaviour is processing.
                                                                                             Speed
                 Now, we can consider the different types of computers, such as Supercomputer,     Storage
                 Mainframe  computer,  and  and  Minicomputer  as  different  objects.  This  is     Portability
                 because all the types have a different speeds and storage capacities, and also    Behaviour:
                 some  are  portable,  such  as  laptops,  whereas  some  should  be  fixed,  such  as     Processing
                 supercomputers.

                                                              Computer Class






                            Supercomputer                        Desktop                           Laptop




                       Characteristics:                 Characteristics:                  Characteristics:
                       Speed = 415.53 PFLOPS            Speed = 1.5 GHz approx            Speed = 1.5 GHz approx
                       Storage = 200 to 300 gigabytes   Storage = 1 to 4 terabytes        Storage = 1 terabytes
                       Portability = fixed              Portability = heavy but can be    Portability = can be taken
                                                        shifted to other position         anywhere
                       Behaviour:
                       Processing = parallel processing,   Behaviour:                     Behaviour:
                       so very fast                     Processing = serial processing    Processing = serial processing



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