How to convert hashmap to JSON object in Java

Question

How to convert or cast hashmap to JSON object in Java, and again convert JSON object to JSON string?

Answer 1

    import org.json.JSONObject;

    HashMap map = new HashMap<>();
    String[] list={"Grader","Participant"};
    String[] list1={"Assistant","intern"};
    map.put("TeachingAssistant",list);
    map.put("Writer",list1);
    JSONObject jsonObject = new JSONObject(map);
    System.out.printf(jsonObject.toString());

    // Result: {"TeachingAssistant":["Grader","Participant"],"Writer":["Assistant","intern"]}