Road to Object
Oriented
Programming
Advanced programming ce244
Sharif University of Technology
Feb 2007
Sunday, February 18, 2007
Taha Abachi
1
Outline
Deadlines
 Objects
 Object Oriented Languages
 Editing your first java program
 Compiling, running and debugging
 Homework

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Deadlines
By the end of the week you should have :
 The Java CD
 Java installed on your machines
 Edited, run, debugged your first Java
programs without any trouble
 Examined Java IDEs
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Objects

Abstraction
Programming languages
2. Problem space
1.

Definition
State : internal data
2. Behavior : methods
3. Identity : each object can be uniquely
distinguished from every other object
1.
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Features of an Object
An object has an interface
 An object provides services
 The hidden implementation
 Data encapsulation
 Reusing the implementation
 Inheritance:reusing the interface

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Features of an Object (cont’d)

Sample object

Date :




Day : 1..31
Month : 1..12
Year : 1300..1500
Problems

Inconsistent data: no dependency to other fields


Inflexible representation

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Day := 32
Date : longint
Date := 28351 days passed after a specific date
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Features of an Object (cont’d)

Clients of the code
 Yourself
 Teammates
 Customers
 An

infant programmer
Solution : Separating implementation
form interface

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More Secure and flexible
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Object Oriented Languages
1.
2.
3.
4.
5.
Everything is an object.
A program is a bunch of objects telling each
other what to do by sending messages.
Each object has its own memory made up of
other objects.
Every object has a type.
All objects of a particular type can receive
the same messages.
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Installing Java
Install JDK
 Install Java Documentation
 API(Application programming
Interface)
 Set Environment variables

 Choose
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a text editor
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Java Characteristics

Portability :
 compile
programs to a intermediary format
called JBC
C:\>javac HelloWorld.java to produce HelloWorld.class

Interpreting : JVM
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Portability
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Java is Object Oriented
Every thing in Java is an Object.
 Objects in OOP mirror the properties
and behavior of the real world objects.
 They have their own set of data and
functions (called method) that operate
on these data.

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First Program in Java
Use a text editor
 Write down your program


Java is case sensitive
Compile your program
 Run

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HelloWorld
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello World");
}
}
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Java program files
Each class is saved in a file of the same
name with java extension.
 Note java is case sensitive language,
even as far as the class file names are
concerned.
 The Hello class should be saved in a file
called HelloWorld.java class .

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Syntax Highlighting
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello World");
}
}
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The method main ( )


The main() method is the point where a Java
program starts running.
Any executable Java class must have the
main() method in this specific format:
public static void main(String[ ] args){
…………..
…………..
}
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Time to compile

Use javac command to compile your java
programms :
C:\> javac HelloWorld.java
HelloWorld.class (JBC file) is created
You may face some errors
 Correct erroneous parts and compile
again

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Run

The Java command is used to run the
class (JBC) file:
c:\> Java HelloWorld
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Congratulations
You are a Java programmer NOW!
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Java Development Environments

Sun's JDK is not an environment.
 Sun's
Java Workshop
 Microsoft's Visual J++
 Symantec's Cafe
 Borland's J Builder
 Metrowerks' Code Warrior
 Tek-Tools' Kawa.
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Java Development Environments

My candidates :
 IntelliJ
IDEA
 Eclipse
 Textpad
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Homework



Install Java properly
Write and Test you first Java program
Design an object oriented environment for
manipulating geometrical shapes :
 Different
subtypes (square, circle, etc.)
 Common characteristics (fields & methods)
 Particular characteristics

Use UML (Unified Modeling Language)
notation
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Questions?
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