Concrete class as generic param

Is there any difference between those definitions?

 public class开发者_JS百科 Foo<String> {}
 public class Foo{}

UPDATED Can first one have any real usage?

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Yes, the first is equivalent to Foo<T> but with the type parameter named String (which is not java.lang.String) instead of T. So you aren't actually using a concrete class as the type parameter (that isn't legal... try changing the declaration to class Foo<java.lang.String>).