Format List<Map<String,String>> using jackson

Question

I want to map an object to json to look like this:

 {"MyClass" : 
      [
        {"key" : "value"},
        {"key" : "value"}
      ]}

However my code is giving me:

{"MyClass" : {
      "list" : {
        "key" : "value",
        "key" : "value"
      }

And my code is like this:

public class MyClass {

    private List<Map<String,String>> list;

    //getters & setters......
  }

And:

Map<String, String> map1 = new HashMap<String,String>();
map1.put("key", "value");

Map<String,String> map2 = new HashMap<String,String>();
map2.put("key","value");

List<Map<String,String> list = new ArrayList<Map<String,String>();
list.add(map1);
list.add(map2);

And I am using ObjectMapper to map the values. What can I do to get the layout I want?

the code seems to work, what's the problem? the names don't match? — shahaf
– shahaf, Commented Apr 12, 2018 at 15:15
it works but not the same format I want. For example, I don't want the name of the list printed — user3871995
– user3871995, Commented Apr 12, 2018 at 15:18
this is the name of the variable, you can change it to different name or use @JsonProperty notation as my example below — shahaf
– shahaf, Commented Apr 12, 2018 at 15:25

shahaf · Accepted Answer · 2018-04-12 15:23:15Z

1

using your code

class MyClass  {

    @JsonProperty("MyClass")
    public List<Map<String,String>> list;

    public static void main(String[] args) throws JsonProcessingException {
        Map<String, String> map1 = new HashMap<String,String>();
        map1.put("key", "value");

        Map<String,String> map2 = new HashMap<String,String>();
        map2.put("key","value");

        List<Map<String,String>> list = new ArrayList<Map<String,String>>();
        list.add(map1);
        list.add(map2);

        MyClass d = new MyClass();
        d.list = list;

        ObjectMapper objectMapper = new ObjectMapper();

        String json = objectMapper.writeValueAsString(d);
        System.out.println(json);
    }
}

output

{"MyClass":[{"key":"value"},{"key":"value"}]}

I used @JsonProperty to change the name but you can also change the name of the var from list to whatever

Note: this is just draft implementation... don't use public class vars, and such...

edited Apr 12, 2018 at 15:23

answered Apr 12, 2018 at 15:17

shahaf

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2 Comments

user3871995 Over a year ago

I'm not getting that layout on mine, I'm using prettyprinter to print, could that make a difference?

shahaf Over a year ago

@user3871995 pretty print effect only the display format not the structure, what do you get when running my example code?

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