27.6. Real-World Examples of Design Patterns

Try these first

1. 1.

   What is the purpose of the Singleton Pattern?

   Hint

   Think about when you need a single point of control.

2. 2.

   How does the Observer Pattern function?

   Hint

   Consider situations where one action affects multiple listeners.

3. 3.

   What does the Singleton Pattern ensure?

   • Multiple instances of a class
   • Only one instance of a class
   • No instances of a class

   Hint

   Think about a logging service that should only have one instance.

4. 4.

   The Observer Pattern is primarily used for what?

   • True
   • False

   Hint

   Remember how alerts are sent to multiple listeners.

5. 5.

   Design a basic logging system in code, ensuring it uses the Singleton Pattern. Provide methods for logging at different severity levels.

   Hint

   Think about how to enforce the single instance control.

6. 6.

   Implement a simple UI with components that use the Observer and Composite patterns. How will state changes be reflected in observers?

   Hint

   Consider the update mechanism for notifying observers.