Java generics: Bound mismatch.Looking for the valid substitute -

i have couple of generic classes:

public interface data<e> {} public interface clonable<e extends clonable<e>> {} public interface naturalnumberinterface extends data<naturalnumberinterface> {} public class naturalnumber implements naturalnumberinterface {} public interface setinterface<e extends data<e>> extends clonable<setinterface<e>> {} public class set<e extends data<e>> implements setinterface<e> {} 

when i'm trying create new instance of set set<naturalnumber> s=new set<naturalnumber>(); compiler says:

naturalnumber not valid substitute type parameter <e extends data<e>> of type set<e>

maybe can me find mistake, cause spent long time , didn't find solution.

i assume setinterface defined in same way listinterface , data interface data<t>.

the generic argument of setinterface f-bounded: e extends data<e>. in current code naturalnumber type extends data<naturalnumberinterface>. if e naturalnumber, condition violated should extend more specific type data<naturalnumber>.

you should use f-bounds naturalnumberinterface well:

public interface naturalnumberinterface<t extends naturalnumberinterface<t>> extends data<t> public class naturalnumber implements naturalnumberinterface<naturalnumber> 

this way work.