What is class hierarchies in java?

Answer 1

The top level class in Java is class Object. Every other class inherits from Object and therefore Object is the top most in the class hierarchy.

If you extend a class from Object such as class Animal and further extend Animal with class Dog then the hierarchy is as follows:

Object

|

Animal

|

Dog

Code for this hierachy is as follows:

class Animal {

}

class Dog extends Animal {

}

We don't need to write class Animal extends Object because every class extends from Object so it does not need to be stated.