06_interfaces_abstract.md

06 — Interfaces & Abstract classes

Interfaces

• Define a contract: methods without implementation (until default methods in later Java versions).
• A class implements an interface and must provide implementations for its methods.

Abstract classes

• Can contain implemented and abstract methods. Use when there's shared code among subclasses.

When to use

• Use interface for capabilities ("can-do"), abstract class when sharing state/implementation between related classes.

Example: InterfacesAbstractExample.java demonstrates an interface Driveable and an abstract class Vehicle.