The observer pattern can be applied in many different ways to a design. This video takes you through a basic implementation that can be used to inspire your own use of the observer pattern.
- [Instructor] Let's take a look at the Java code … to implement our basic observer pattern design. … We'll start with the Subject interface. … This specifies the three methods … the concrete subject must implement, … registerObserver, to allow observers to register themselves, … removeObserver, to allow observers to stop participating, … and notifyObservers, which will make sure … all the observers are notified … if the data in the subject changes. … The concrete subject, named SimpleSubject here, … implements that interface, … and so must implement those three methods. … The SimpleSubject manages the list of observers, … in this case, using an ArrayList. … And, it manages the data … that the observers are interested in. … Here, that's just an integer, value. … Observers call registerObserver to add themselves … to the list of observers in the subject. … And they call removeObserver … to remove themselves from the list. … Let's say the value in the subject changes. … Perhaps, another object calls setValue to change the value. …
- What are design patterns?
- Encapsulating code that varies with the Strategy pattern
- The limitations of inheritance
- Using the Adapter pattern
- Implementing the Observer pattern
- Extending behavior with composition and the Decorator pattern
- Encapsulating iteration with the Iterator pattern
- Object creation with the Factory Method pattern
- Using design principles to guide your object-oriented design
Skill Level Intermediate
1. Design Patterns
2. The Strategy Pattern
3. The Adapter Pattern
4. The Observer Pattern
Using the Observer pattern2m 23s
5. The Decorator Pattern
6. The Iterator Pattern
7. The Factory Patterns
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