Java Reference
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Note Type parameters cannot have lower bounds. Angelika Langer explains the
rationale for this restriction in her “Java Generics FAQs” (see ht-
TypeParameters.html#FAQ107 ).
Type Parameter Scope
This scope includes the formal type parameter list of which the type parameter is
a member. For example, the scope of S in SortedShapesList<S extends
Shape&Comparable<S>> isallof SortedShapesList andtheformaltypepara-
meter list.
anestedtype'sformaltypeparameterlist.Forexample, Listing3-54 masksanenclosing
class's T type parameter.
Listing 3-54. Masking a type variable
class EnclosingClass<T>
static class EnclosedClass<T extends Comparable<T>>
EnclosingClass 's T type parameter is masked by EnclosedClass 's T type
parameter, which specifies an upper bound where only those types that implement the
Comparable interfacecanbepassedto EnclosedClass .Referencing T fromwith-
in EnclosedClass referstothebounded T andnottheunbounded T passedto En-
closingClass .
For example, you might specify EnclosedClass<U extends Compar-
able<U>> . Although U is not as meaningful a name as T , this situation justifies this
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