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javagenericsbounded-wildcard
IVR Avenger
IVR Avenger

Reputation: 15494

Bounded type as method parameter?

I am trying to enforce a particular subclass type on an abstract method, like so:

public abstract class Searcher {    
  public abstract SearchResult search(<T extends SearchInput> searchInput);
}

This is to ensure that subclasses of Searcher have to extend a corresponding subclass of SearchInput. I know I can use a bounded type for the method's return type, but I can't seem to get it to work as a method argument. Is this possible in Java?

Upvotes: 0

Views: 375

Answers (1)

Giorgi Tsiklauri
Giorgi Tsiklauri

Reputation: 11120

Have a look at Java documentation on Generic Methods:

The syntax for a generic method includes a list of type parameters, inside angle brackets, which appears before the method's return type.

You need:

public abstract class Searcher {
    public abstract <T extends SearchInput> SearchResult search(T searchInput);
}

Point is, that generic type declaration must happen before the signature part.

Upvotes: 1

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