將 Map 型別的資料轉換為 JSON String

    Group group = new Group();  
    group.setId(1);  
    group.setName("Ke");  
      
    User user1 = new User();  
    user1.setId(2);  
    user1.setName("Liu");  

    User user2 = new User();  
    user2.setId(3);  
    user2.setName("Yue");  
    group.getList().add(user1);  
    group.getList().add(user2);  
      
    Map<Integer, Object> map = new HashMap<Integer,Object>();  
    map.put(1, "No.1");  
    map.put(2, "No.2");  
    map.put(3, group.getList());  
      
    String jsonString = JSON.toJSONString(map);  
    System.out.println(jsonString);  

輸出

{1:"No.1",2:"No.2",3:[{"id":2,"name":"Liu"},{"id":3,"name":"Yue"}]}