The Java unit test: public void testAnimation() throws JsonParseException, JsonMappingException, IOException { ObjectMapper mapper = new ObjectMapper(); Animation animation = mapper.readValue(new File("data/entityTest.json"), Animation.class); } The JSON: { "frames" : [ { "ref" : "data/bullet.jpg" } ], "duration" : 1 } The error: org.codehaus.jackson.map.exc.UnrecognizedPropertyException: Unrecognized field "frames" (Class org.newdawn.slick.Animation), not marked as ignorable