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CSE115: Introduction to Computer Science I

CSE115: Introduction to Computer Science I. Dr. Carl Alphonce 219 Bell Hall 645-4739 alphonce@buffalo.edu. Phones off Signs out. Announcements. Exam 2 – 1 week away covers material from exam 1 up to & including 10/15 review on Monday 10/18 exam on Wednesday 10/20. Agenda.

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CSE115: Introduction to Computer Science I

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  1. CSE115: Introduction to Computer Science I Dr. Carl Alphonce 219 Bell Hall 645-4739 alphonce@buffalo.edu

  2. Phones off Signs out

  3. Announcements • Exam 2 – 1 week away • covers material from exam 1 up to & including 10/15 • review on Monday 10/18 • exam on Wednesday 10/20

  4. Agenda • interfaces and realization • type hierarchy

  5. Interfaces and Realization • form of interface definition • function of an interface • realization (“implements”) relationship

  6. Form of an interface • header + body • header • access control modifier • keyword ‘interface’ • name (generally an adjective, following class name conventions, but prefixed with an upper-case ‘I’) • body • method specifications (method headers followed by ‘;’, also called method declarations, as opposed to method definition)

  7. Example public interface ICollarable { public void addCollar(Collar collar); public Collar removeCollar(); }

  8. Example public class Dog implements ICollarable { private Collar _collar; public Dog(Collar collar) { _collar = collar; } public void setCollar(Collar collar) { _collar = collar; } public Collar removeCollar() { Collar temp = _collar; _collar = null; return temp; } }

  9. Example public class Dog implements ICollarable { private Collar _collar; public Dog(Collar collar) { _collar = collar; } public void addCollar(Collar collar) { _collar = collar; } public Collar removeCollar() { Collar temp = _collar; _collar = null; return temp; } }

  10. Example ICollarable x; x = new ICollarable(); NO! Cannot instantiate. x = new Dog(); OK if Dog implements ICollarable x = new Cat(); OK if Cat implements ICollarable

  11. Calling methods ICollarable x; x = new ICollarable(); NO! Cannot instantiate. x = new Dog(); OK if Dog implements ICollarable x = new Cat(); OK if Cat implements ICollarable x.addCollar(new Collar()); OK x.removeCollar(); OK x.walk(); NO! Not all ICollarable objects define this method!

  12. Demo in Eclipse

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