Download DS and Java File

University of Petra
Faculty of Information Technology
Data Structures in Java: An Introduction
Our world if full of DATA
These data need to be processed
Dr techn
Dr.
techn. Dipl
Dipl. Inform
Inform. Bassam Haddad
Associate Professor of Computer Science
Faculty of Information Technology
Petra University
Office: 7312 Ext. 340
@ op.e .jo
haddad@uop.edu.jo
Introduction
PART I
ƒHow to store data in a Computer Program?
ƒHow to organize the involved Data?
ƒHow data are arranged in relation to each other?
ƒWhich
Which operations and parameters?
ƒWhich data are kept in the memory?
ƒWhich are calculated when needed?
ƒWhich are kept in files, and how the files are arranged?
ƒWhich method is more efficient?
Course No.: 601221
Prerequisite:601212 PL-II
2010-1
ƒWhich Programming Language?
ƒ Why JAVA?
ƒIs our program correct (Testing & Verification)
ƒWhat about the maintenance of a Program
Based on:
Data Structures and Abstractions with JAVA
Frank M. Carrano & W. Savitech, Pearson Education, 2Ed, 2007
(Changing the Environment,
Environment New Demands on the Program)
.....
We need to organize our Data used in a program
In Data Structures
We need to specify such Data Structures
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© Bassam Haddad 2010
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Data Structures in Java: An Introduction
Specification of Data Structures
Abstract Data Types
ADT
Formal Model ( Specification) that describes:
ƒThe Types of Data
ƒOperations on these Data
ƒInvolved parameters
Implementation
Realization in a PL
C++, Java, C, Prolog, …
Data Structures in Java: An Introduction
Which DS we will learn in this course?
ƒLists
ƒStack
ƒRegular Queue
ƒDeque
ƒPriority Queue
ƒ Implementations
p
ƒTrees
ƒGraph
ƒDictionary
ƒRecursion
ƒSearching and Sorting
ƒAlgorithm Analysis
Data Structures in JAVA
ƒWe call these (Abstract) Structures Data Structures in
the Implementation phase
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Objects & Classes
An object is a program construct that
ƒ Contains data (Instance Variables, data
fields, data members, properties, ...)
ƒ Performs certain actions
• The actions are called methods (functions,
behavior, operations, member functions, …)
• The actions interact to form the solution to a
given problem
Objects & Classes
Example of a class:
A class is a type
yp or kind of object
j
Objects of the same class have
ƒ The same kinds of data
ƒ The same methods
• A class definition is a general description of
ƒ What
Wh t the
th object
bj t is
i
ƒ What it can do
From DS and Abstr. Carrano & Savitch 2003
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Objects & Classes
Objects & Classes: An Example
Class Modifier: public, final, abstract
Instantiation of the Class Automobile
public class Name
NajeebCar
slemanCar
bassamCar
{ private String first;
private String last;
// first name
// last name
Variable Modifier:
protected, public,
private
Scope: final, static
< Definitions of methods are here. >
Jordan
Mercedes
} // end Name
Jeep
Method Modifier: public, protected, private
Scope: final, static
public
bli String
St i getFirst()
tFi t()
{ return first;
} // end getFirst
body of the method
public: no restriction on where to use the class, any other Java class can use it
final: cannot be overridden in a derived class
abstract: has no definition and must be overridden in a derived class. Avoiding the
creation of objects of such class.
Abstract methods: derived class should implement them
static method: can be shared by all objects of the class
From DS and Abstr. Carrano & Savitch 2003
© Bassam Haddad 2010
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Objects & Classes
Example:
Java Implementation Strategy
Implementation Strategy:
ƒInterface
ƒThe Class
ƒThe Client
public class Name
{p
private String
g first;;
private String last;
public Name () // Defualt Constuctor
{ }
public Name(String fName, String lName)
{ first=fName;
last=lName; }
The Interface
1)
public String getFirst()
{ return first; }
public String getLast()
{ return last; }
public interface NameInterface
{
……
}
The class
public
bli String
St i toString()
t St i ()
{ return first + " "+ last; }
/*t
/*toString
St i M
Method*/
th d*/
2)
public static void main(String[ ] args)
{
Name a = new Name();
Name b= new Name("Bashar", "ahmad");
System.out.println(a.getLast()); // Null
The Client
3)
System.out.println(a.getFirst()); //Null
System.out.println(b.getLast());
System.out.println(b.getFirst());
public class Name implementsNameInterface
{
……
}
public class NameClient
{
……
}
a=b;
/* reference to a, alias to a*/
System.out.println(a);
//*because
because of toString Menthod*/
Menthod /
System.out.println(b); }
}
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Example: Java Implementation Strategy
NameInterface
Example: Java Implementation Strategy
Class: Name implementation
public interface NameInterface
{
public String getFirst();
/**Task:getFirst getting the first Name
*@param: no
*@return: String*/
public class Name implements NameInterface {
private String first;
private String last;
public Name() // Default Constructor
{ }
public Name(String fName, String lName)
{ first=fName;
last=lName; }
public String getLast();
/**Task: getLast
*@param: no
*@return: String */
public String toString();
/**Task:toString printing an object
*@param: no
*@return: String*/
public String getFirst()
{ return first; }
public String getLast()
{ return last; }
}
public String toString()
{ return first + " "+ last; }
//*toString
toString Method
Method*//
}
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Example: Java Implementation Strategy
Composition: A class uses composition when it has
a data filed that is an instance of another class
client class with main
public class ClientName{
public static void main(String[ ] args)
{
NameInterface a = new Name();
NameInterface b= new Name(“Najeeb", “momo");
a=b;
system.out.println(a.getLast());
system.out.println(a.getFirst()); }
}
© Bassam Haddad 2010
Composition
13
Example : an object of type Student.
private Name fullName;
private String id;
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Assignment 1
Use the composition concept to write a Java program
based on the introduced implementation Strategy:
1) A StudentInterface with at least the following
methods
public Name g
p
getName()
()
public String getId ()
public String toString() and the constructors
2) Student class implementing the StudentInterface
3 A client class defining at least three student
objects
j
with their fullName and and id’s
4) Test you class in the LAB
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