How do you use a generic type as return value and a generic type as a parameter?

Question

I try to create an abstract class with generics. The business logic is to translate a text from one language to another. There must be a Translator class for each l

Answer 1

Just add it where you define your Generics :

public abstract class Translator <T extends OriginalText, V> {            
    public abstract <V extends LanguageTranslation> V translate(T originalText);
}

Btw, this is confusing because the V definition is overriden in your method. Why not doing this :

public abstract class Translator <T extends OriginalText, V extends LanguageTranslation> {            
    public abstract V translate(T originalText);
}

EDIT: explaining why you have a warning on V

It's exactly the same as :

public abstract class Translator <T extends OriginalText, V> {            
    public abstract <K extends LanguageTranslation> K translate(T originalText);
}

Now inside the method you have 3 generics :

• K of runtime determined subtype of LanguageTranslation
• T of runtime determined subtype of OriginalText
• V runtime determined subtype of Object (default constraint)