How to use java object as a key In JSON?

Question

Hi I have a Java Class like,

// code
class A{
  private int i;
  private String j;
// getters/setters
}

I want to use this object as a map key in my json, how i can do this? e.g : i want something like - {javaObject:value}

Not possible: all JSON keys are strings. If you can make a bijective mapping between your class and strings, you might be able to do it that way (use the string representation of your object as key) — Amadan, Oct 19 '16 at 08:12
And the `value` in the `{javaObject:value}` is what exactly? — Adrian Colomitchi, Oct 19 '16 at 08:12
Hi Adrian, Let say i have a hash map like:- Map map=new HashMap(); and i want it's JSON string. — Kumar-Sandeep, Oct 19 '16 at 08:14
this can be achieved using as key a complex json type... but... it is absolutely necessary? — Jordi Castilla, Oct 19 '16 at 08:14
yup it is, can you give me the format accoring to given object of A as JSON key i.e {new A():value} — Kumar-Sandeep, Oct 19 '16 at 08:29
What exactly is the output that you want when using class A as a key? — 1615903, Oct 19 '16 at 08:50

Ashutosh Jha · Answer 1 · 2016-10-19T10:53:47.957

0

In that case when you want to convert object to json, use this link. Gson can be used to do that.

edited Oct 19 '16 at 10:53

answered Oct 19 '16 at 08:47

Ashutosh Jha

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It's not working as it uses the objects tostring, also below link says that it is not possible:- http://stackoverflow.com/questions/11628698/can-we-make-object-as-key-in-map-when-using-json – Kumar-Sandeep Oct 19 '16 at 09:27

score 0 · Answer 2 · answered Oct 19 '16 at 10:05

You can bind key with any object and map the key-name with json key, use Jackson library to achieve this -

1.You can create data binding POJO like below -

  class A{

  @JsonProperty("key_name")
  private int i;
  @JsonProperty("key_name")
  private String j;
 // getters/setters

}

2.If you want Object A to be used as a key, then create a pojo like below -

 class JsonData{
 @JsonProperty("key_name")
 private A object;
 //getter //setter
 }

score 0 · Answer 3 · answered Oct 19 '16 at 12:12

Hi I've find the correct answer, actually for complex object as a map key in JSON we have to use:-

GsonBuilder gsonBuilder = new GsonBuilder();
gsonBuilder.enableComplexMapKeySerialization();
Gson mapper = gsonBuilder.create();
//Object to JSON in String
String jsonInString = mapper.toJson(myobject); //myobject=any object of class A

How to use java object as a key In JSON?

3 Answers3