How do I pretty-print existing JSON data with Java?

Question

I have a compact JSON string, and I want to format it nicely in Java without having to deserialize it first -- e.g. just like jsonlint.org does it. Are there any libraries out there that provides this?

A similar solution for XML would also be nice.

JSONObject has a `toString(int)` where you provide spacing for pretty printing. — Buhake Sindi, May 31 '11 at 09:14
@The Elite Gentleman: I would need to deserialize the JSON data to get a JSONObject, wouldn't I? — neu242, May 31 '11 at 10:26
@neu242, no, JSONObject is a JSON data already. Why do you want to do that? — Buhake Sindi, May 31 '11 at 10:29
I would look at Nashorn (part of a java installation). http://stackoverflow.com/questions/4105795/pretty-print-json-in-java#29094958 — jarry_dk, Jan 19 '17 at 10:11

Heath Borders · Answer 1 · 2014-10-28T13:10:57.203

90

int spacesToIndentEachLevel = 2;
new JSONObject(jsonString).toString(spacesToIndentEachLevel);

Using org.json.JSONObject (built in to JavaEE and Android)

edited Oct 28 '14 at 13:10

answered Oct 18 '14 at 17:57

Heath Borders

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What library does this use? As is it is not a very helpful answer. – Andrew Oct 28 '14 at 09:47
@Andrew Backer, this is not a library. As Heath Borders said, it is built into the Android libraries. I've tested this and it works perfectly without any libraries. – tambykojak Nov 25 '14 at 08:11
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Hm... I'm not developing for Android, and I don't deploy to a java EE container... hence the need for clarification. Thanks for adding that :) So for someone like me, distributing a java app targeting SE, it would be a library such as `org.json:json:20090211`? – Andrew Nov 26 '14 at 09:29
for those of us using Android, this is very useful and not really clear in the quick view of the docs. Didn't expect it to be built in. – manroe Jun 05 '15 at 22:40
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**`org.json.JSONObject` is not built into JavaEE**. The `JSON-P` library for `JsonObject` is `javax.json.JsonObject`. – Buhake Sindi Jul 11 '16 at 08:07
greattttt, this is very useful – dadan Oct 19 '17 at 03:15
The dependency with group ID of `org.json` and artifact ID of `json` in the Maven POM file or in your Gradle also supports prettifying JSON data by passing in the indent level in the `toString(int)` method. – tom_mai78101 May 15 '20 at 18:50
This is really useful in Spring Boot. – Arjun Sunil Kumar May 22 '20 at 14:23
this is very useful. but one problem. if data is large, all data not showing in. Any suggestion – Aminul Haque Aome Jun 10 '21 at 10:37

score 21 · Answer 2 · answered Jul 23 '17 at 13:24

Use gson. https://www.mkyong.com/java/how-to-enable-pretty-print-json-output-gson/

Gson gson = new GsonBuilder().setPrettyPrinting().create();
String json = gson.toJson(my_bean);

output

{
  "name": "mkyong",
  "age": 35,
  "position": "Founder",
  "salary": 10000,
  "skills": [
    "java",
    "python",
    "shell"
  ]
}

score 12 · Answer 3 · answered Aug 22 '17 at 15:36

12

Another way to use gson:

String json_String_to_print = ...
Gson gson = new GsonBuilder().setPrettyPrinting().create();
JsonParser jp = new JsonParser();
return gson.toJson(jp.parse(json_String_to_print));

It can be used when you don't have the bean as in susemi99's post.

answered Aug 22 '17 at 15:36

vcycyv

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Instantiating `JsonParser` is now deprecated. Use the static method `JsonParser.parseString(json_String_to_print)` instead. – kousen Oct 09 '19 at 22:31
This is the right answer let's up vote it !! – Dan Ortega Dec 17 '19 at 22:41
this must be accepted answer! – aligur Jul 29 '20 at 12:49

score 10 · Answer 4 · edited May 19 '14 at 23:54

10

In one line:

String niceFormattedJson = JsonWriter.formatJson(jsonString)

or

System.out.println(JsonWriter.formatJson(jsonString.toString()));

The json-io libray (https://github.com/jdereg/json-io) is a small (75K) library with no other dependencies than the JDK.

In addition to pretty-printing JSON, you can serialize Java objects (entire Java object graphs with cycles) to JSON, as well as read them in.

edited May 19 '14 at 23:54

Davoud Taghawi-Nejad

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answered Feb 24 '14 at 15:24

John DeRegnaucourt

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Used this little library, with some modifications to the output format. Thanks for letting me know about it. – Andrew Oct 28 '14 at 10:40
Not only was this the first solution to work on my environment, it finally confirmed that I know how to use Gradle to properly pull in thrid-party libraries! A good day, Thanks! – Shadoninja Dec 26 '15 at 21:00
I hoped that this tiny library would reformat an existing JSON string without deserializing it first but looking at the source code proved me wrong. This formatJson(..) method internally deserializes the JSON string and then serializes it back to a formatted JSON string. – Sven Döring Oct 08 '19 at 14:20

score 9 · Answer 5 · edited Jul 11 '16 at 08:06

9

If you are using jackson you can easily achieve this with configuring a SerializationFeature in your ObjectMapper:

com.fasterxml.jackson.databind.ObjectMapper mapper = new ObjectMapper();

mapper.configure(SerializationFeature.INDENT_OUTPUT, true);

mapper.writeValueAsString(<yourObject>);

Thats it.

edited Jul 11 '16 at 08:06

Buhake Sindi

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answered Feb 19 '14 at 16:00

Lars Rückemann

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score 4 · Accepted Answer · edited Sep 17 '13 at 15:17

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I think for pretty-printing something, it's very helpful to know its structure.

To get the structure you have to parse it. Because of this, I don't think it gets much easier than first parsing the JSON string you have and then using the pretty-printing method toString mentioned in the comments above.

Of course you can do similar with any JSON library you like.

edited Sep 17 '13 at 15:17

Alois Mahdal

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answered May 31 '11 at 09:45

Waldheinz

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Links are broken. – Valentyn Kolesnikov Oct 18 '19 at 04:37

score 2 · Answer 7 · answered Aug 18 '16 at 08:09

I fount a very simple solution:

<dependency>
    <groupId>com.cedarsoftware</groupId>
    <artifactId>json-io</artifactId>
    <version>4.5.0</version>
</dependency>

Java code:

import com.cedarsoftware.util.io.JsonWriter;
//...
String jsonString = "json_string_plain_text";
System.out.println(JsonWriter.formatJson(jsonString));

Valentyn Kolesnikov · Answer 8 · 2021-03-16T17:45:01.657

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Underscore-java library has methods U.formatJson(json) and U.formatXml(xml).

edited Mar 16 '21 at 17:45

answered Aug 17 '19 at 10:04

Valentyn Kolesnikov

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How do I pretty-print existing JSON data with Java?

8 Answers8

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