Types of Inheritance

Types of Inheritance

1. Five Types (beginner map!)

Single (one parent) → Multilevel (chain) → Hierarchical (siblings) → Multiple (two parents — BANNED for classes!) → Hybrid (mix!). Java allows ALL via classes EXCEPT multiple (use interfaces!).

class A {}
class B extends A {}              // SINGLE (B ← A)
class C extends B {}              // MULTILEVEL (C ← B ← A, gets all!)
class D extends A {}              // HIERARCHICAL (B,D siblings ← A!)
// class E extends B, D {}         // MULTIPLE — ERROR! (diamond confusion!)
interface I1 { void x(); } interface I2 { void y(); }
class F implements I1, I2 {       // MULTIPLE via interfaces (LEGAL!)
    public void x() {} public void y() {}
}

Interfaces fix: default clash must be overridden explicitly (compiler forces choice!).

4. Exam Table

Type	Java class?	Example
Single	Yes	Dog extends Animal
Multilevel	Yes	Puppy extends Dog extends Animal
Hierarchical	Yes	Cat,Dog extends Animal
Multiple (class)	NO	use interfaces!
Hybrid	via interfaces	class + interfaces mix

5. Exam Points

• Five types + diagram + diamond reason — 7 marks, very frequent.
• Multiple-ban + interface fix — 5 marks, favourite.