Inheritance (is-a) relationships are derived child classes that inherit attributes and methods from their parent class. Composition (has-a) relationships are classes whose attributes are comprised of other classes. Each relationship has its advantages and disadvantages. See the link below for best uses of each.
For example:
class Animal { }
class Dog extends Animal { }
This means Dog IS-A animal
2. HAS-A simply means reference
For example:
class Nip { }
class Dog { private Nip nip;}
This means Dog HAS-A Nip
Hope this helped!! :)
