René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"State checking for extending abstract classes","articleBody":"Currently, reusing state refinements from an abstract superclass in a concrete class is not fully implemented, and gives an error like the one below.\n\u003cimg width=\"1718\" height=\"850\" alt=\"Image\" src=\"https://github.com/user-attachments/assets/1cd0d7af-57e3-4b45-8e36-7fa4f4be5504\" /\u003e\n\nExample for abstract class `java.net.URLConnection`:\n```java\n@ExternalRefinementsFor(\"java.net.URLConnection\")\n@StateSet({\"setup\", \"connected\"})\npublic interface URLConnectionRefinements {\n \n    @StateRefinement(to=\"setup(this)\")\n    public void URLConnection(URL url);\n\n    @StateRefinement(from=\"setup(this)\")\n    public void setDoInput(boolean doinput);\n\n    @StateRefinement(from=\"setup(this)\", to=\"connected(this)\")\n    public void connect();\n\n    @StateRefinement(from=\"connected(this)\")\n    public Object getContent();\n \n}\n```\n\nExtended in class `URLExt`:\n```java\nclass URLExt extends URLConnection{\n\n    public URLExt(URL url){\n        super(url);\n    }\n\n    @Override\n    public void connect() throws IOException {\n        // TODO Auto-generated method stub\n        throw new UnsupportedOperationException(\"Unimplemented method 'connect'\");\n    }\n    \n}```\n\nTested in:\n```java\nclass Testurl {\n    void test() throws URISyntaxException, IOException {\n\n        URLExt u = new URLExt(new URI(\"http://example.com\").toURL());\n        u.setDoInput(false); // should not be an error but it is \n        u.getContent(); // should be an error\n\n    }\n}\n```\n\n","author":{"url":"https://github.com/CatarinaGamboa","@type":"Person","name":"CatarinaGamboa"},"datePublished":"2025-12-10T15:00:42.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/131/liquidjava/issues/131"}