getClass and type reification?

[Tapio Niemela]

I'm reading "Java generics and collections" by Maurice Naftalin & Philip Wadler. I'm having trouble understanding the following sentence on page 101. "The restrictions on class tokens lead to useful property. Wherever a type of the form Class<T> appears, the type T should be a reifiable type"

However I'm allowed to do following:

		String x="x";
		Class<? extends String>xlass=x.getClass();//yes..

where <? extends String>isn't reifiable type (as parameterized types with bound are not reifiable) , so either the quoted sentence isn't true or I have misunderstood something

Also I'm not allowed to do following

		String x="x";
		Class<String>xlass=x.getClass();//no..

where <String> actually is reifiable type. So, please help me to understand the sentence..

[Stephan van Hulst]

Would you please quote the context for those that don't have the book?

[Rob Spoor]

That example doesn't make it exactly clear because the reference type and object type match. Consider this better example:

Object x = "";
Class<? extends Object> cls1 = x.getClass(); // OK, because whatever class the object actually is of, it is or extends Object
Class<Object> cls2 = x.getClass(); // not OK because the class is Class<String>, not Class<Object>