java - Create generic Interface restricted to own class -

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i create generic interface 2 classes i'm not sure how specify generics right way.

public class thinga implements thing {     public thinga createcopy(thinga original); }  public class thingb implements thing {     public thingb createcopy(thingb original); }

i tried this.

public interface thing<v extends thing<v>> {     public v createcopy(v original);  }

but i'm still able things this, shouldn't allowed.

public class thingb implements thing<thinga> {     public thinga createcopy(thinga original); }

there no this key-word generics (nor methods parameters , return values declaration) , cannot want.

in other words interface permit ensure methods in class use consistent types, not reference class type itself.


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