The Interface Segregation Principle (ISP) advocates for designing lean, specific interfaces tailored to the needs of each client, rather than bloated interfaces with numerous methods that clients are forced to depend on, even if they don’t use them.
Consider our ongoing example of a drawing application. Imagine an interface called IShape with methods like draw(), resize(), and getArea(). While a Rectangle class would use all these methods, a Line class would only need draw(), not resize() or getArea(). Forcing the Line class to depend on an interface with irrelevant methods violates ISP.
The solution is to segregate IShape into more specific interfaces like IDrawable (with only draw()), IResizable (with resize()) and IMeasurable (with getArea()). Rectangle would implement all three, while Line would only implement IDrawable. This way, each class only depends on the specific functionality it needs.
ISP promotes more focused, role-based interfaces that better encapsulate responsibilities. Clients are not coupled to methods they don’t use, allowing interfaces to remain lean and less prone to change. This enhances codebase stability and maintainability over time, as changes to unused interface methods won’t ripple across the system to affect clients that don’t depend on them.
Author: John Rowan
I am a Senior Android Engineer and I love everything to do with computers. My specialty is Android programming but I actually love to code in any language specifically learning new things.Share this:
