Oop lecture1-chapter1(review of java)

Object Oriented Programming-Java
Rebaz M. Nabi
Email: rebazmala86@gmail.com
1
OOP 2nd Class TCI-SPU Rebaz M. nabi
@2015-2016

Class Policy
RESPECT
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Background
• Deitel, H.M. & Deitel, P.J. (2009). Java: How to Program. Prentice Hall (8th
ed.).
• Flanagan, D. (2005). Java in a nutshell : a desktop quick reference. O’Reilly
(5th ed.).
• Flanagan, D. (2004). Java examples in a nutshell : a tutorial companion to
Java in a nutshell. O’Reilly (3rd ed.).
• Gamma, E., Helm, R., Johnson, R. & Vlissides, A. (1995). Design patterns:
elements of reusable object-oriented software. Addison-Wesley.
• Bloch, J. & Gafter, N. (2005). Java puzzlers. Addison-Wesley.
• Object Oriented Modeling and Design with UML Michael Blaha and James
Rambaugh – PEARSON second edition.
• UML Distilled: A Brief Guide to the Standard Object Modeling Language
(3rd Edition) by Martin Fowle.
• Douglas Bell. Software Engineering. Third Edition. 2000.
• Cay Horstmann, “ Big Java”, 3rd Edition, John Wiley and Sons, 2008, ISBN:
978-0-470-10554-2
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Objectives
• The goal of this course is to provide students with the
ability to write programs in Java and make use of the
concepts of Object-Oriented Programming (the principles
of OOP which is inheritance, polymorphism, abstract, and
encapsulation). Examples and discussions will use Java
primarily, but other languages may be used to illustrate
specific points where appropriate. As well as this course
considered the GUI programs in java and JDBC to access
database applications from java code. The course is
designed to accommodate students with diverse
programming backgrounds; it is taught with a mixture of
lectures and practical sessions where students can work at
their own pace from a course handbook. Each practical
class will culminate in an assessed exercise.
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Aims
After learning the course the students should be able to:
• Be familiar with the main features and limitations of the Java
language;
• Be able to write a Java program to solve a well specified problem;
• Understand the principles of OOP;
• Understand how to use GUI components in Java
• Be able to demonstrate good object-oriented programming skills in
Java;
• Be able to describe, recognise, apply and implement selected
design patterns in Java;
• Develop database-driven applications
• Identify exception handling methods.
• Implement multithreading in object oriented programs.
• Prepare UML diagrams for software system
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Course Content
• Revision of principles of programming in java
• Principles of Object-Oriented Programming
• Classes and Objects in Java
• Graphical User Interface
• Encapsulation and inner class
• Packages and Standard libraries
• Interface and Abstract class
• Exceptions Handling
• Input Output stream
• Java Database Connectivity JDBC
• Collection Classes
• Concurrent programming
• Software Testing and Flow Diagram
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Basic Definitions
• A computer is a machine that performs
calculations and processes information
– A computer works under the control of a computer
program
• A computer program is a set of instructions that
tell a computer what to do
• Hardware refers to the electronic and mechanical
components of a computer
• Software refers to the programs that control the
hardware
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Computers
HardwareSoftware
Computers
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Hardware
• A computer's hardware is organized into
several main subsystems or components
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Software
• There are two main types of software:
• Application software
– designed to provide a particular task or service
– word processors, computer games, spreadsheet programs,
and Web browsers
• System software
– includes programs that perform the basic operations that
make a computer usable
– An example of the system software is operating systems,
which contains programs that manage the data stored on
the computer's disks, such as Windows or Linux
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Programming Languages
• Programmers write instructions in various programming
languages, some directly understandable by computers and
others requiring intermediate translation steps. Hundreds of
computer languages are in use today. These may be divided
into three general types:
1. Machine languages( Numbers)
2. Assembly languages ( Keywords)
3. High-level languages(Close to Human English )
4. New Generation Languages
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Machine languages
• Any computer can directly understand only its own
machine language. Machine language is the "natural
language" of a computer and as such is defined by its
hardware design. Machine languages generally consist
of strings of numbers (ultimately reduced to 1s and 0s)
that instruct computers to perform their most
elementary operations one at a time.
Samples
– +1300042774
– +1400593419
– +1200274027
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assembly languages
• Machine-language programming was simply too slow
and tedious for most programmers. These
abbreviations formed the basis of assembly languages.
Translator programs called assemblers were developed
to convert early assembly-language programs to
machine language at computer speeds.
• Although such code is clearer to humans, it is
incomprehensible to computers until translated to
machine language.
– load
– add
– store
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High level languages
• To speed the programming process, high-level languages were
developed in which single statements could be written to
accomplish substantial tasks. Translator programs called
compilers convert high-level language programs into machine
language. High-level languages allow programmers to write
instructions that look almost like everyday English and contain
commonly used mathematical notations.
• grossPay = basePay + overTimePay
–
C, C++, Microsoft's .NET languages (e.g., Visual Basic
.NET, Visual C++ .NET and C#) and Java are among the
most widely used high-level programming languages.
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Compilers and Interpreters
• The process of compiling a high-level language program into
machine language can take a considerable amount of
computer time. Interpreter programs were developed to
execute high-level language programs directly.
• Translators are used to translate a high-level or source code
program (in C++ or Java) into machine language code or
object code
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Compilers and Interpreters e)
• Source code translators come in two varieties:
– An interpreter translates a single line of source code
directly into machine language and executes the code
before going on to the next line of source code
• for example PHP and Perl.
– A compiler translates the entire source code program
into executable object code. The object code can be
run directly without further translation
• for example C, C++, and Pascal
• Java programs use both compilation and interpretation in
their translation process
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History of Java
• Java evolved from C++, which evolved from C.
• The C language was evolved from B by Dennis
Ritchie(Father of Computer Programming(my point of
view) at Bell Laboratories and was originally implemented
in 1972. It initially became widely known as the
development language of the UNIX operating system.
Today, most of the code for general-purpose operating
systems (e.g., those found in laptops, desktops,
workstations and small servers) is written in C or C++.
• C++, an extension of C, was developed by Bjarne
Stroustrup in the early 1980s at Bell Laboratories (now part
of Lucent). C++ provides a number of features that "spruce
up" the C language, but more important, it provides
capabilities for object-oriented programming
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History of Java (Cont.)
• Microprocessors are having a profound impact in
intelligent consumer-electronic devices. Recognizing
this, Sun Microsystems in 1991 funded an internal
corporate research project code-named Green, which
resulted in the development of a C++-based language
that its creator, James Gosling, called Oak after an oak
tree outside his window at Sun.
• It was later discovered that there already was a
computer language called Oak. When a group of Sun
people visited a local coffee shop, the name Java was
suggested, and it stuck.
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Why Java?
 Object Oriented
 Object-oriented languages divide programs into separate modules, called objects,
that encapsulate the program's data and operations
 Robust
 meaning that errors in Java programs don't cause system crashes as often as errors
in other programming languages
 Platform Independent
 Platform is a particular kind of computer system, such as a Macintosh or Windows
system
 Java program can be run without changes on different kinds of computers
 Distributed Language
 which means that its programs can be designed to run on computer networks
 Secure
 Java designed to be used on networks, Java contains features that protect against
untrusted code
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Software Development Process
• source code is written in plain text files with the
.java extension
• source files are then compiled into .class files by
the java compiler
• A .class contains bytecodes: the machine
language of the Java Virtual Machine (Java VM).
• The java runs the application with an instance of
the Java VM
•
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Fundamentals of Programming
in Java
• Java VM is available on many different
operating systems
• The same .class files are capable of running on
– Microsoft Windows
– Solaris OS
– Linux
– Mac OS
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The Java Platforms
• The Java platform runs on top of other hardware-
based platforms like Windows, Linux or Mac OS
• has two components:
– The Java Virtual Machine (VM)
– The Java Application Programming Interface (API)
• The Java Virtual Machine (Java VM) is the base
for the Java platform
• The API is a large collection of software
components grouped into libraries known as
packages
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Write a java program
• The necessary tools are:
– The Java SE Development Kit 8 (JDK) you can download the latest
version here:
– http://www.oracle.com/technetwork/java/javase/downloads/jdk8-
downloads-2133151.html
– For description and how does it work click below link:
– http://docs.oracle.com/javase/7/docs/webnotes/install/index.html
– Text pad( will be provided during practical lectures) or you can
download it here
– http://www.textpad.com/download/
– Eclipse or NetBeans (prefer NetBeans)
• Creating an Application in Windows
– Create a source file in .java extension
– Compile the source file into a .class java compiler
– Run the program
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Java Program Development
• Phase 1.0 : Editor
• Phase 2.0 : Compiler
• Phase 3.1 : Class Loader
• Phase 3.2 : Bytecode Verifier
• Phase 3.3 : Java Virtual Machine
• Program is edited in a text editor, much as a
paper for an English class is edited in a word
processor.
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Java Conventions
• About Java programs, it is very important to keep in mind the following
points.
• Case Sensitivity - Java is case sensitive, which means identifier Hello and
hello would have different meaning in Java.
• Class Names - For all class names the first letter should be in Upper Case.
If several words are used to form a name of the class, each inner word's
first letter should be in Upper Case.
Example: class MyFirstJavaClass
• Method Names - All method names should start with a Lower Case letter.
If several words are used to form the name of the method, then each
inner word's first letter should be in Upper Case.
Example: public void myMethodName()
• Program File Name - Name of the program file should exactly match the
class name.
Example : Assume 'MyFirstJavaProgram' is the class name. Then the file
should be saved as 'MyFirstJavaProgram.java’
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Java Identifiers
• All Java components require names. Names used for classes,
variables and methods are called identifiers.
• In Java, there are several points to remember about identifiers.
They are as follows:
• All identifiers should begin with a letter (A to Z or a to z), currency
character ($) or an underscore (_).
• After the first character identifiers can have any combination of
characters.
• A reserved key word cannot be used as an identifier.
• Most importantly identifiers are case sensitive
• Examples of legal identifiers: age, $salary, _value, __1_value
• Examples of illegal identifiers: 123abc, -salary.
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Java Modifiers
• Like other languages, it is possible to modify classes, methods,
etc., by using modifiers. There are two categories of
modifiers:
• Access Modifiers: default, public , protected, private
• Non-access Modifiers: final, abstract, static
• We will be looking into more details about modifiers in the
next section.
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Java Variables
- Local Variables
• Local variables are visible only within the declared method,
constructor or block.
• Access modifiers cannot be used for local variables.
• There is no default value for local variables so local variables
should be declared and an initial value should be assigned
before the first use.
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Java Variables
- InstanceVariables
• Instance variables are declared in a class, but outside a method, constructor or any
block.
• Access modifiers can be given for instance variables.
• The instance variables are visible for all methods, constructors and block in the
class. Normally, it is recommended to make these variables private (access level).
However visibility for subclasses can be given for these variables with the use of
access modifiers.
• Instance variables have default values. For numbers the default value is 0, for
Booleans it is false and for object references it is null. Values can be assigned
during the declaration or within the constructor.
• Instance variables can be accessed directly by calling the variable name inside the
class. However within static methods and different class ( when instance variables
are given accessibility) should be called using the fully qualified name .
ObjectReference.VariableName.
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Java Variables
- Class Variables
• Class variables are variables declared with in a class, outside
any method, with the static keyword.
• Access modifiers can be given for instance variables.
• In the case of having static variables or methods, you can
access or use them by using the class’s name following it’s
variable or method name
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Variables
 Definition: a variable is a location in the computer memory
which can store a value of a certain type
 Each variable has a name, a type, a size, and a value.
 Examples of variables: 1 byte
byte age = 22;
short shortNum;
int intNum; age
long longNum;
char mychar;
boolean isMale; Name
value
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22

Java Keywords
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abstract Assert boolean break
byte Case catch char
class Const continue default
do Double else enum
extends Final finally float
for Goto if implements
import Instanceof int interface
long Native new package
private Protected public return
short static strictfp super
switch synchronized this throw
throws transient try void
Volatile while

Comments
• Java statements direct the operations of a program,
while comments are used to help document what
the program does.The Java supports three kinds of
– /* text */
• The compiler ignores everything from /* to */.
– /** documentation */
• This indicates a documentation comment
– // text
• The compiler ignores everything from // to the end of
the line.
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Java Data Type
– ** documentation */
• This indicates a documentation comment
– // text
• The compiler ignores everything from // to the end of
the line.
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Escape Sequences
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Notation Character represented
n Newline (0x0a)
r Carriage return (0x0d)
f Formfeed (0x0c)
b Backspace (0x08)
s Space (0x20)
t tab
" Double quote
' Single quote
backslash
ddd Octal character (ddd)
uxxxx
Hexadecimal UNICODE character
(xxxx) 35

Declares and Initializes Variable
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Java Modifiers Types
- Access Control Modifiers
• Java provides a number of access modifiers to set
access levels for classes, variables, methods and
constructors. The four access levels are:
• Visible to the package, the default. No modifiers are
needed.
• Visible to the class only (private).
• Visible to the world (public).
• Visible to the package and all subclasses (protected).
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Java Modifiers Types
- Non Access Modifiers
• Java provides a number of non-access modifiers to achieve
many other functionality.
• The static modifier for creating class methods and variables
• The final modifier for finalizing the implementations of
classes, methods, and variables.
• The abstract modifier for creating abstract classes and
methods.
• The synchronized and volatile modifiers, which are used for
threads.
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Oop lecture1-chapter1(review of java)

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