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Singleton Structure
Singleton Pattern-Quiz
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Extension Variation Pattern
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Perfect Singleton
Pattern Conclusion
Creational Patterns
Creational Design Pattern
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Common Creational Patterns
Factory Pattern
Factory Method-Exercise
Factory Method Structure
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factory Pattern Summary
Structural Patterns
Structural Pattern Example
Patterns Help Programmers
Common Structural Patterns
Flyweight Pattern
Flyweight Consequences
Flyweight Suitability
Behavioral Patterns
Define Behavioral Patterns
Mediator Pattern Applicability
Observer Pattern Tradeoffs
Designing Software
How to Choose Pattern
How To Apply Pattern
Lessons Learned
Combine Design Patterns
Design Pattern Limitations
Traffic flow System
Course Conclusion
Observed Object - Exercise
An Observed Object
Objective:
Write a Time class as an Observed object.
Rewrite the Time class from Module three so that it adheres to both the Singleton and the Observed pattern. This class should simply count seconds for an amount of time given in the constructor. Each second, it should notify registered observers of the current time using their timeChanged() method. When you are finished, the class should look like this:
Time class with methods currentTime, endOfTime, getInstance, init, run(), addTimeObserver, removeTimeObserver
The run() method increments the currentTime, and notifies each registered listener of that change.
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