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CSE115: Introduction to Computer Science I. Dr. Carl Alphonce 219 Bell Hall Office hours: M-F 11:00-11:50 645-4739 alphonce@buffalo.edu. State systems. State-based system: system’s behavior based on its current state Many systems are state-based: Cable/Satellite TV box Wrist-watch
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CSE115: Introduction to Computer Science I Dr. Carl Alphonce 219 Bell Hall Office hours: M-F 11:00-11:50 645-4739 alphonce@buffalo.edu
State systems • State-based system: • system’s behavior based on its current state • Many systems are state-based: • Cable/Satellite TV box • Wrist-watch • Cell phone interface
State Diagram push button OFF ON push button
Polymorphism • Behavior determined by method of object, because… • it’s the object that responds: • the type of the object determines response • the type of the reference to object doesn’t
Polymorphism declared type of variable a supertype of actual type of object
Polymorphism(in proxy pattern) context delegates method call to concrete tool
Delegation in State code public class DeskLamp { private IState _state; public DeskLamp() { _state = new Off(); } public void pushButton() { _state.pushButton(this); } public void setState(IState s) { _state = s; } }