In what cases is it advisable to apply the principle of composition in system design?

The principle of composition is advisable to apply when:

• You need to create complex objects from simple components, ensuring flexibility and reusability.
• It is required to avoid tight coupling between classes (unlike inheritance).
• You need to dynamically change the behavior of objects at runtime.
• You want to implement loosely coupled systems where components interact through interfaces.

For example, in Android, composition is often used to combine various functionalities in an Activity or Fragment through dependency injection, delegation, or using patterns like "Delegate".

This improves testability, extensibility, and maintainability of the code.