Lecture_01.pdf

1
Object Oriented
Programming-Java
OOP vs POP, Java,
Java Technologies,
Prepared by: Said H Said
The University of Dodoma

2
Procedural Oriented
Programing (POP)
 Program is divided into small parts called
functions
 Importance is not given to data but to
functions as well as sequence of actions to
be done
 Does not have any access specifies
 In POP, Data can move freely from function
to function in the system

3
POP Cont…
 To add new data and function in POP is not
so easy
 In POP, Most function uses Global data for
sharing that can be accessed freely from
function to function in the system
 POP does not have any proper way for hiding
data so it is less secure
 In POP, Overloading is not possible
 Example of POPL are : C, VB, FORTRAN,
Pascal

4
Object Oriented
programing(OOP)
 Program is divided into parts called objects
 Importance is given to data rather than
procedures or functions to mimic real world
realm
 OOP has access specifies named Public,
Private, Protected, etc
 In OOP, objects can move and communicate
with each other through member
functions/methods

5
OOP cont…..
 OOP provides an easy way to add new data
and function/methods
 In OOP, data cannot move easily from function
to function, it can be kept public or private so we
can control the access of data
 OOP provides Data Hiding so provides more
security
 In OOP, overloading is possible in the form of
Function Overloading and Operator Overloading
 Example of OOP are : C++, JAVA, VB.NET,
C#.NET Prepared by: Said H Said

6
POP SRUCTURE……
Main Function
Function 1 Function 2 Function 3
Function 2 Function 5
Function N

7
OOP SRUCTURE……
Class 1 {
Data
Methods
}
Class 2 {
Data
Methods
}
Class n {
Data
Methods
}

Java
 General purpose programming language
 Is simple
 Is scalable
 Is object oriented
 Is similar to C and C++
8

9
Java
 A Programming Language and a Platform
 Java Platform
 Java Virtual Machine (Java VM)
 Java Application Programming Interface

10
Java
 It is Platform Independent (Write Once Run
Anywhere)

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Advantages of Java
 Easy to learn, Familiar C++ like syntax
 Pure Object Oriented Language
 Extensive API, which means that
programmers write lesser amount of code
 Extensive Documentation
 Faster Application Development because of
code re-use
 Platform Independence
 Automatic Garbage Collection

12
History of Java
 Project Green by Sun Microsystems to create
a pure object oriented language based on
C++, to overcome the limitations and
complexities of C++ (1990)
 Aimed at embedded systems in consumer
electronic devices (interactive television,
VCR, washing machines, etc.)
 Originally named ‘Oak’

13
History of Java
 Failed to win recognition in embedded
systems and embedded systems were not
making a rapid progress
 During the same period world wide web
(www) was going through an exponential
growth
 Oak was aimed at supporting interactive web
pages together with the development of a
new web browser, Web Runner (1994)

14
History of Java
 ‘Oak’ renamed ‘Java’ and ‘Web Runner’
renamed ‘Hot Java’
 Formal Announcement of Java Language
and Hot Java browser in Sun World ’95
 Commercial web browsers starting with
Netscape begin supporting Java
 Later Java evolved into other technologies
like Java applets (interactive web content)

15
Use of Java
 Desktop Applications such as acrobat reader,
media player, antivirus etc.
 Web Applications such as irctc.co.in,
javatpoint.com etc.
 Enterprise Applications such as banking
applications.
 Mobile
 Embedded System
 Smart Card
 Robotics
 Games etc.

Prepared by: Said H Said The University of
Dodoma
16
Different Java Technologies
 JVM (Java Virtual Machine): is an abstract machine. It
is a specification that provides runtime environment in
which java bytecode can be executed.
 JVMs are available for many hardware and software
platforms. JVM, JRE and JDK are platform dependent
because configuration of each OS differs. But, Java is
platform independent.
 The JVM performs following main tasks:
 Loads code
 Verifies code
 Executes code
 Provides runtime environment

17
 JRE: is an acronym for Java Runtime Environment.
 It is used to provide runtime environment.
 It is the implementation of JVM.
 It physically exists.
 It contains set of libraries + other files that JVM uses at
runtime.
 Implementation of JVMs are also actively released
by other companies besides Sun Micro Systems.

18
 JDK is an acronym for Java Development Kit.
 It physically exists.
 It contains JRE + development tools.

19

20
 IDE’s (Integrated Development Environments): are
tools used for efficient software development
 Different Components of an IDE :
 Editor
 Linker
 Compiler
 Debugger
 All the different components are seamlessly
integrated in an IDE making it easy to use

21
IDEs cont…
 For different programming languages,
different IDE’s are available
 Java Language :
JBuilder, Kawa, NetBeans, eclipse etc.
 C Language :
Borland C, Turbo C, etc.
 IDE’s have capabilities different from each
other and one has to learn the use of an IDE
to get the maximum return

22
Compilation and Execution of
a Java Program
 Create a source file (e.g. :- a file named
“HelloWorld.java”) and type in the source code.
/**
* The HelloWorld class implements an application that
* displays "Hello World!" to the standard output.
*/
public class HelloWorld {
public static void main(String[] args) {
// Display "Hello World!"
System.out.println("Hello World!");
}
}

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Compilation and Execution of
a Java Program
 Compile the source file
 Use the Java compiler :
javac HelloWorld.java
 A byte code file (i.e. a file understandable by the
Java Virtual Machine) is created
 Run the program contained in the byte code
file
 Use the command :
java HelloWorld

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