Class Design: Abstraction

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Class Design Abstraction

• Datatype classes

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Abstraction

• Reducing to only the fundamental aspects.
• What makes a chair a chair?
• What makes a clock a clock?
• What makes a location a location?
• What makes a task a task?

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Two types of classes

• Datatype class
• blueprint for objects
• abstracts some concept
• Examples DrawingTool class, SketchPad class
• Procedural class
• just holds methods
• like a machine
• no abstraction doesnt represent anything
• Example DrawHouse class

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Example Datatype class

• What is an appointment?
• How can we abstract an appointment?

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Example Datatype class

• public class Appointment
• private int year //2007, 2008, etc.
• private int month //0January, 1Feb, etc.
• private int dayOfMonth //careful with this!
• private int dayOfWeek // 0Sunday, 1Monday,
  etc.
• private int startHour //military time 0 23
• private int startMin //0 59
• private int endHour //military time 0 23
• private int endMin //0 59

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Example Procedural Class

• public class CalendarInterface
• public void processAppointments()
• Appointment app new Appointment(2007, 10, 3,
  1, 13, 0, 14, 0)
• public boolean validateAppointment()
• Appointment app calendar.getAppointment(4)
• public boolean updateAppointments()