All throws exception are Checked Exception.Compiler makes sure that a block capable of throwing a CheckedException must/should associate a handler for it.Which if neglected would generate a compile-time error. Example : Block having a Class.forName("class name") statement should throw(s) ClassNotFoundException. Neglecting a handler for Unchecked exception doesn't worry compiler.
Hi Ashok, IllegalArgumentException is definetly an Unchecked Runtime Exception,which would prop-up during runtime when when a method is invoked with an argument which it can not reasonably deal with. Check for categorised exceptions,you will know the list.