java.lang.reflect

Interface WildcardType

public interface WildcardType extends Type

Represents a wildcard type expression, where the type variable is unnamed. The simplest example of this is ?, which represents any unbounded type. Another example is ? extends Number, which specifies any type which is a subclass of Number (Number is the upper bound).

? super String gives the type a less common lower bound, which means that the type must be either a String or one of its superclasses. This can be useful in working with collections. You may want a method to add instances of a class to a collection with a more generic type (e.g. adding Strings to a list of Objects), but don't want to allow users to pass in a collection with a more specific type.

Since: 1.5

Method Summary
Type[]getLowerBounds()

Returns an array of Types, which specify the lower bounds of this type.

Type[]getUpperBounds()

Returns an array of Types, which specify the upper bounds of this type.

Method Detail

getLowerBounds

public Type[] getLowerBounds()

Returns an array of Types, which specify the lower bounds of this type. The default lower bound is null, which causes this method to return an empty array.

In generating the array of Types, each ParameterizedType or TypeVariable is created, (see the documentation for these classes for details of this process), if necessary, while all other types are simply resolved.

Returns: an array of Type objects, representing the wildcard type's lower bounds.

Throws: TypeNotPresentException if any of the types referred to by the lower bounds of this type do not actually exist. MalformedParameterizedTypeException if any of the types refer to a type which can not be instantiated.

getUpperBounds

public Type[] getUpperBounds()

Returns an array of Types, which specify the upper bounds of this type. The default upper bound is Object, which causes this method to return an array, containing just the Type instance for Object.

In generating the array of Types, each ParameterizedType or TypeVariable is created, (see the documentation for these classes for details of this process), if necessary, while all other types are simply resolved.

Returns: an array of Type objects, representing the wildcard type's upper bounds.

Throws: TypeNotPresentException if any of the types referred to by the upper bounds of this type do not actually exist. MalformedParameterizedTypeException if any of the types refer to a type which can not be instantiated.