Answers for "generate json to java"

build json object in java

String jsonString = new JSONObject()
                  .put("JSON1", "Hello World!")
                  .put("JSON2", "Hello my World!")
                  .put("JSON3", new JSONObject().put("key1", "value1"))
                  .toString();

System.out.println(jsonString);

json to java object

String json = "...";
ObjectMapper m = new ObjectMapper();
Set<Product> products = m.readValue(json, new TypeReference<Set<Product>>() {});