18.5 Exception Hierarchy.java

Error and Exception extends Throwable class.
Throwable class is extended by Object class.

Error is divided into :-
1. Thread Death
2. Virtual Machine error ( Out of memory)
3. IO Error

Exception is divided into:-
1. Runtime Exception  (Unchecked Exception)
	- Arithmetic 
	- ArrayIndexOutOfBound
	- Null POinter
- It is your choose to handle or not

2. SQL Exception   (Checked Exception)
- It is necessary to handle

3. IO Exception  (Checked Exception)
- It is necessary to handle