Throwable class which is the base class for an entire family of exception classes, declared in  java.lang package as java.lang.Throwable 

 Throwble(base class for entire exception family)

it consists two main classes

1.Exception:                                                      2.Error

this will further divided into                                  

Runtime Exception                                           
IO Exception
Sql Exception
Malformed URL Exception

     Run time Exception is further divided into number of exceptions
 Null pointer Exception
number format Exception
Classcast Exception
Indexoutofbound Exception and so on