Reuse existing interfaces

• Instead of creating a new interface, reuse one that already exists

  • especially those that are part of the language or common libraries

Benefits

• Reduce bloat

  • Having too many interfaces can make the code too hard to follow

• Reduce cognitive load

  • Existing interfaces mean the devs are already comfortable with them

Negatives

• Interface is a contract for a specific usage, although abstract it might not be abstract enough for use in multiple places

  • Just because an interface is available, and can be used, does not mean it should be used, think about what the interface is for

Example

• Strategy Pattern

  • Instead of new interface, use a Function<INPUT,OUTPUT> or Consumer

    • Can have another interface but that extends theses

  • The implementors will just implement this interface, and override this method

  • These interfaces are single method interfaces, and thus lambdas/method ref can be used