Interfaces

An interface definition can be parameterized by using the following syntax:

<interface> -> [<InterfaceModifiers>] interface <idn>
               ["[" <params> "]"] [<where>]
	       [<ExtendsInterfaces>] <InterfaceBody>

<params> -> <idn> [, <idn>]*

<where> -> where <constraint> [, <constraint>]*

<constraint> -> <idn>  [<whereDecl> ";"]* 

<whereDecl> -> <methodSig> | <constructorSig>

<methodSig> -> [ static ] <ResultType>
	       <MethodDeclarator> [<Throws>]

<constructorSig> -> <ConstructorDeclarator> [<Throws>]

The params clause lists one or more formal parameter names, each of which stands for a type in the parameterized definition. The where clause lists constraints on the parameters. Each constraint identifies the parameter being constrained; the idn in the constraint must be one of those listed in the params. It then identifies the methods/constructors that that parameter must have. For a method it gives the name, and the types of its arguments and results; it also indicates whether the method is static or not. For a constructor, it lists the types of the arguments. The type names introduced in the params clause can be used as types in the remainder of the interface, including the ExtendsInterfaces clause.