Teknik pemrograman berorientasi objek dalam membangun perangkat lunak

1. OOP in
Software Design

2. Review OOP
• What is Class, Object & Method?
• What is Abstraction and Inheritance?
• What is Overloading and Overriding in Polymorphism?
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3. OOP Essentials
 1st step in OOP development is to identify the object and
establish relationship among them
 Type of relationship
 Association
 Aggregation
 Inheritance
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4. Association
 Represent general binary relationship that describes an
activity between two classes.
 Illustrated using solid lines
 May have role name for each class involved which
describes the role played by the class in the relationship.
 Each class involved may specify multiplicity. It could be a
number or interval, describes the number of object being
involved in the relationship
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5. Association
 Example:
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6. Association
 Association may exist between objects of the same class.
 Association is usually represented as a data field in the
class.
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7. Association
public class Student {
private Course[] courseList;
// data field, constructor
// method
}
public class Course {
// data field, constructor
// method
}
public class Faculty {
private Course[] courseList;
// data field, constructor
// method
}
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public class Employee {
private Employee supervisor;
// data field
// constructor
// method
}

8. Association Team Discussion
 A small software house in Bandung has a rule that limiting
one project manager’s responsibility only to one project
while he/she can lead at least one or more small team
related to software modules for the project.
 Determine the relationship between Project Manager, The
Project and the Team, please write the class relationship.
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9. Aggregation
 Special form of association that represents an ownership
between two classes
 Models relationship like : has-a, owns, part-of, employed-
by…
 An object may be owned by several other aggregated
objects.
 If an objects is exclusively owned by an aggregated
object, the relationship is referred to as composition.
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10. Aggregation
public class FinanceConsultant {
private Broker[] brokerList;
//data field
//constructor
//method
}
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public class Share {
private Broker broker;
//data field
//constructor
//method
}

11. Class Design Guidelines
 Class should describe a single entity or a set of similar
operations.
 Single entity with too many responsibilities can be broken
to several classes to separate responsibilities.
 Classes are designed for reuse.
 Provide a public default constructor and override the
equals and toString method whenever possible.
 Follow standard Java programming style and naming
conventions.
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12. Inheritance vs Composition
 Inheritance representing is-a relationship.
 Composition representing has-a relationship.
 Use Inheritance if polymorphism is desirable.
 Use Composition if you don’t care about polymorphism
and wants more flexibility to your design.
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13. Inheritance vs Composition
public class Person {
public Person() { }
private String name;
// getter and setter method
}
public class Mahasiswa extends Person {
public Mahasiswa() { }
private String npm;
// getter and setter method
}
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public class ProjectManager {
public ProjectManager() { }
private String firstName;
private String lastName;
// getter and setter method
}
public class Project {
public Project() { }
private String projectName;
private ProjectManager projectManager;
// getter and setter method
}

14. Inheritance
 Models the is-a relationship between two classes.
 Strong is-a relationship
 Describes a direct inheritance relationship between two classes.
Represented using extends.
 Example : public class Mahasiswa extends Person { }
 Weak is-a relationship
 Describes that a class has certain properties. Can be
represented using interfaces
 Example : public class Purchase implements Transaction { }
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15. Inheritance vs Abstract
 Strong is-a relationship better use abstract class.
 Weak is-a relationship better use interfaces.
 Interfaces are more flexible than abstract class, subclass
can only extends one superclass but may implement
many interfaces.
 Interfaces doesn’t have concrete methods.
 Both can be combined. ex. Set or List in Java Collection
Framework.
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16. Discussion
A small CD rental wants to build a database system so they
can manage their CDs collection. The objects involved in the
system are Customer (anyone who borrow CDs), Employee
(anyone who runs the rental’s management), and the CD
itself. Create the classes and their relationship.
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17. Thank you
Bayu Rimba Pratama, ST, M.Kom