wicket-user-guide/src/main/asciidoc/resources/resources_12.adoc

Since interface _IResource_ is marked as functional interface, a custom resource can also be implemented with a simple lambda expression that consumes a _IResource.Attributes_ parameter:

[source,java]
----
IResource helloWorldRes = (attributes) -> 
     attributes.getResponse().write("Hello world!");
----

Lambda expressions come in handy also with _ResourceReference_ factory methods _of_ that accept a resource supplier as argument. Let's say we want to mount the resource of the previous example. Using lambdas the code looks like this:

[source,java]
----
@Override
public void init() {
  super.init();

  IResource helloWorldRes = (attributes) -> 
     attributes.getResponse().write("Hello world!");
     
  ResourceReference resRef = ResourceReference.of("helloworld", () -> helloWorldRes);        

  mountResource("/helloworld", resRef);
}
----

As first argument for factory methods we can specify the name of the resource reference or a key for it (an instance of _ResourceReference.Key_)