Returns a new instance of an anonymous (inner) class. The syntax is similar to
Returns a new instance of a unique (anonymous) class. The class inherits from the list of
supers, where at most one of the elements should be the base class being extended from, and the rest are interfaces.
This is roughly equivalent to:(begin (define-simple-class
field-declis as for
define-class, except that we also allow an abbreviated syntax. Each
field-decldeclares a public instance field. If
object-finitis given, it is an expression whose value becomes the initial value of the field. The
object-initis evaluated at the same time as the
objectexpression is evaluated, in a scope where all the
field-names are visible.
method-declis as for
An anonymous class is commonly used in the Java platform where a
function language would use a lambda expression.
Examples are call-back handlers, events handlers, and
In these cases Kawa lets you use a lambda expression as a short-hand
for an anonymous class. For example:
(button:addActionListener (lambda (e) (do-something)))
is equivalent to:
(button:addActionListener (object (java.awt.event.ActionListener) ((actionPerformed (e ::java.awt.event.ActionEvent))::void (do-something))))
This is possible when the required type is an interface or abstract class with a Single (exactly one) Abstract Methods. Such a class is sometimes called a SAM-type, and the conversion from a lambda expression to an anonymous class is sometimes called SAM-conversion.
Note that Kawa can also infer the parameter and return types of a method that overrides a method in a super-class.