VELTECH HIGHTECH Dr.RANGARAJAN Dr.SAKUNTHALA ENGINEERING COLLEGE                                     
                                                DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING 
                                               CS8391- OBJECT ORIENTED PROGRAMMING 
                                                                              UNIT-1 
                                              IINTRODUCTION TO OOP AND JAVA FUNDAMENTALS 
                                                                                          
                                  Object  Oriented  Programming  -  Abstraction  –  objects  and  classes  -  Encapsulation- 
                            Inheritance - Polymorphism- OOP in Java – Characteristics of Java – The Java Environment - Java 
                            Source File -Structure – Compilation. Fundamental Programming Structures in Java – Defining 
                            classes  in  Java  –  constructors,  methods  -access  specifiers  -  static  members  -Comments,  Data 
                            Types, Variables, Operators, Control Flow, Arrays , Packages - JavaDoc comments. 
                                                                                    
                      1.     Explain oops concepts in Detail. 
                       
                             Object-Oriented Programming: 
                       
                      OOP is defined as object oriented programming. 
                      Basic Concepts of OOP 
                      1) Class 
                      2) Object 
                      3) Method 
                      4) Inheritance 
                      5) Data Abstraction 
                      6) Data Encapsulation 
                      7) Polymorphism 
                      8) Message Passing 
                       
                      Defining the Class: 
                      A class is defined by the user is data type with the template that helps in defining the properties. Once 
                      the class type has been defined we can create the variables of that type using declarations that are 
                      similar to the basic type declarations. In java instances of the classes which are actual objects 
                      Eg: 
                             Class classname [extends superclassname] 
                             { 
                                    [fields declarations;] 
                                    [methods declaration;] 
                             } 
                    VELTECH HIGHTECH Dr.RANGARAJAN Dr.SAKUNTHALA ENGINEERING COLLEGE                                                    Page 1 
                     
                         VELTECH HIGHTECH Dr.RANGARAJAN Dr.SAKUNTHALA ENGINEERING COLLEGE                                     
                                  DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING 
                 
                Field Declaration 
                Data is encapsulated in a class by placing data fields inside the body of the class definition. These 
                variables are called as instance variables. 
                     Class Rectangle 
                     { 
                            int length; 
                            int width; 
                     } 
                 
                Method Declaration 
                A Class with only data fields has no life, we must add methods for manipulating the data contained in 
                the class. Methods are declared inside the class immediate after the instance variables declaration. 
                Eg: 
                     class Rectangle 
                     { 
                            int length; //instance variables 
                            int width; 
                            Void getData(int x, int y) // Method Declartion 
                            { 
                                  Length =x; 
                                  Width = y; 
                            } 
                     } 
                Creating the objects: 
                An  object  in  java  essentially  a  block  of  memory,  which  contains  space  to  store  all  the  instance 
                variables. Creating an object is also referred as instantiating an object. Object in java are created using 
                the new operator. 
                Eg: 
                Rectangle rec1; // Declare the object 
                Rec1 = new Rectangle //instantiate the object 
              VELTECH HIGHTECH Dr.RANGARAJAN Dr.SAKUNTHALA ENGINEERING COLLEGE                   Page 2 
               
                         VELTECH HIGHTECH Dr.RANGARAJAN Dr.SAKUNTHALA ENGINEERING COLLEGE                                     
                                  DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING 
                The above statements can also be combined as follows 
                Rectangle rec1 = new Rectangle; 
                Methods: 
                Methods are similar to functions or procedures that are available in other programming languages. 
                Difference B/w methods and functions 
                Difference b/w method and function is method declared inside class, function can be declared anywhere 
                inside are outside class 
                Writing methods in java 
                if we had to repeatedly output a header such as: 
                System.out.println("GKMCET"); 
                System.out.println ("Allapakkam"); 
                System.out.println ("Meppedu Road"); 
                We could put it all in a method like this: 
                     public static void printHeader() 
                     { 
                     System.out.println("GKMCET"); 
                     System.out.println("Allapakkam"); 
                     System.out.println("Meppedu Road"); 
                     } 
                Inheritance: 
                Inheritance is the process of forming a new class from an existing class or base class. The base class is 
                also known as parent class or super class, the new class that is formed is called derived class. 
                Derived class is also known as a child class or sub class. Inheritance helps in reducing the overall code 
                size(reusability) of the program, which is an important concept in object oriented programming. 
                 
                Data Abstraction: 
                Data abstraction increases the power of programming language by creating user defined data types. 
                Data abstraction also represents the needed information 
                in the program without presenting the details. 
                 
                Data Encapsulation: 
              VELTECH HIGHTECH Dr.RANGARAJAN Dr.SAKUNTHALA ENGINEERING COLLEGE                   Page 3 
               
                                   VELTECH HIGHTECH Dr.RANGARAJAN Dr.SAKUNTHALA ENGINEERING COLLEGE                                     
                                                DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING 
                      Data  encapsulation  combines  data  and  functions  into  a  single  unit  called  class.  When  using  Data 
                      Encapsulation, data is not accessed directly; it is only accessible through the functions present inside the 
                      class. Data encapsulation enables the important concept of data hiding possible. 
                       
                      Polymorphism: 
                      Polymorphism allows routines to use variables of different types at different times. An operator or 
                      function can be given different meanings or functions. The ability of objects to respond differently to 
                      the same message or function call. 
                       
                      Message passing: 
                      A message passing system provides primitives for sending and receiving messages using objects. These 
                      primitives may by either synchronous or asynchronous or both. 
                      2.     Explain the Characteristics/ Features of Java in Detail. 
                       
                    Features of Java 
                    The main objective of Java programming language creation was to make it portable, simple and secure 
                    programming language. Apart from this, there are also some awesome features which play important role 
                    in the polularity of this language. The features of Java are also known as java buzzwords. Following is a 
                    list of most important features of Java language. The Java Features given below are simple and easy to 
                    understand. 
                        ➢  Simple 
                        ➢  Object-Oriented 
                        ➢  Portable 
                        ➢  Platform independent 
                        ➢  Secured 
                        ➢  Robust 
                        ➢  Architecture neutral 
                        ➢  Dynamic 
                        ➢  Interpreted 
                        ➢  High Performance 
                        ➢  Multithreaded 
                        ➢  Distributed 
                    Simple 
                    Java is very easy to learn and its syntax is simple, clean and easy to understand. According to Sun, Java 
                    language is simple because: 
                    syntax is based on C++ (so easier for programmers to learn it after C++). 
                    removed many confusing and/or rarely-used features e.g., explicit pointers, operator overloading etc. 
                    No need to remove unreferenced objects because there is Automatic Garbage Collection in java. 
                    Object-oriented 
                    Java is Object-oriented programming language. Everything in Java is an object. Object-oriented means 
                    we organize our software as a combination of different types of objects that incorporates both data and 
                    behaviour. 
                    Object-oriented  programming(OOPs)  is  a  methodology  that  simplifies  software  development  and 
                    maintenance by providing some rules. 
                                  Basic concepts of OOPs are: 
                    VELTECH HIGHTECH Dr.RANGARAJAN Dr.SAKUNTHALA ENGINEERING COLLEGE                                                    Page 4