java - Implementing class embedded in an interface -

assume have interface class embedded in (the purpose being interface must provide 'type'. interface has methods using 'type'. so, in file s.java, have

public interface s {     public class stype     {     }      public abstract void f( stype );  } 

i want implement interface, , try this, in file ss.java:

public final class ss implements s {     public class stype extends java.util.hashset<integer>     {     }      public void f( stype )     {         // ...     } } 

however, when try compile these files ("javac s.java ss.java"), usual error message "ss not abstract , not override abstract method f(stype) in s" indicating "f()" in concrete class not proper implementation of "f()" in interface. why?

try with:

public final class ss implements s{       public class stype extends java.util.hashset<integer>     {     }      public void f(s.stype a) {         // ..     } } 

edit:

perhaps, need this:

public interface s<stype> {     public void f( stype );  }  public final class ss implements s<hashset<integer>> {      public void f(hashset<integer> ){         // ...     } }