Java Tree Structure design pattern(?)

I have list of strings like:

A.B.C.D.1

A.B.C.D.2

A.B.C.D.3.a

A.B.C.E.1

A.B.C.E.2.a

A.B.C.E.2.b

...etc - and +600 times more rows...

Every string shout execute different action and send response different message after finish.

Should i create class A with few nodes - every node will do the same and last leaf will have 2 methods? Thats 600+ classes... plus if anything will change I will have to change all of those classes.

I belive there is a better way to do that...

What is the best way to implement that?