How to generate random JSON string in Java?

Question

I want to test a feature of apache kafka.So I need generate random JSON string in Java.(My production data is JSON format.)

I google it, and I found the sites:

These are not the best answer.

In ruby, the gem faker can generate fake data.

In Java, what library can generate fake data? what library can generate fake JSON string?

I had exactly the same requirement, and end up building my own library - https://github.com/mangatmodi/RandomJson However, if you want to stream data to Kafka, you could use the following rather than using a library and writing own code - https://github.com/everwatchsolutions/json-data-generator — Mangat Rai Modi, Apr 29 '19 at 22:19

Ronak Poriya · Answer 1 · 2016-10-14T05:24:22.067

Checkout this open source java library randomizer. Based on YOUR_MODEL_CLASS using annotation random data generation is possible.

Generator<YOUR_MODEL_CLASS> generator = new Generator<>(YOUR_MODEL_CLASS.class);
List<YOUR_MODEL_CLASS> fakeObj = generator.generate(NO_OF_RECORDS);
Gson gson = new Gson();
String jsonString = gson.toJson(fakeObj);

There are many inbuilt annotation available,which we can set upon instance variables defined in YOUR_MODEL_CLASS.Go through guide on library page.

Andrei Ciobanu · Answer 2 · 2020-10-12T16:10:31.657

You can use mockneat in order to do that. It's a library specialised in generating all kind of "fake" data. Check out the documentation to see what you can "fake" and how.

There is a wiki page that shows you how you can generate a Random JSON:

MockNeat mockNeat = MockNeat.threadLocal();
Gson gson = new GsonBuilder()
                        .setPrettyPrinting()
                        .create();

String json = mockNeat
                     .reflect(UserProfile.class)
                     .field("name", mockNeat.names().full())
                     .field("userName", mockNeat.users())
                     .field("email", mockNeat.emails())
                     .field("profiles",
                                mockNeat.reflect(Profile.class)
                                        .field("profileId", mockNeat.ints().range(100, 1000))
                                        .field("profileAdded", mockNeat.localDates().toUtilDate())
                                        .list(2))
                     .map(gson::toJson) /* Transforms the UserProfile class into a 'pretty' json. */
                     .val();

System.out.println(json);

And the given result is (of course, the results are different each time):

{
  "name": "Cecila Starbird",
  "userName": "moistben",
  "email": "randiexyst@hotmail.co.uk",
  "profiles": [
    {
      "profileId": 964,
      "profileAdded": "Mar 19, 1973 12:00:00 AM"
    },
    {
      "profileId": 854,
      "profileAdded": "Jun 3, 1978 12:00:00 AM"
    }
  ]
}

Later edit:

The new preferred way of generating json is the following: https://www.mockneat.com/tutorial/#json-and-xml

Disclaimer: I am the author of the library.

How to generate random JSON string in Java?

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