PrettyPrint JSON with Jackson

Question

I am using jackson 2.8.4 and try to pretty-print (i.e. format nicely with indentation) some JSON that I have got in a one-line String called json.

I tried

ObjectMapper mapper = new ObjectMapper();
mapper.enable(SerializationFeature.INDENT_OUTPUT);
json = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(json);

and

ObjectMapper mapper = new ObjectMapper();
mapper.enable(SerializationFeature.INDENT_OUTPUT);
json = mapper.writeValueAsString(json);

but the JSON String json still is just one line.

EDIT:

Before:

{"artifacts":[{"general":{"name":"jersey-client-2.26.jar","path":"doartifac/spielwiese-group-cache/org/glassfish/jersey/core/jersey-client/2.26/jersey-client-2.26.jar","pkg_type":"Maven","sha256":"3e44b7db8691eb0b2a6751eda888150b9ba1092a5805f11e4727fd4904407a41","component_id":"org.glassfish.jersey.core:jersey-client:2.26"},"issues":[],"licenses":[{"name":"CDDL-1.0","full_name":"Common Development and Distribution License (CDDL)\n            1.0","more_info_url":["http://www.opensource.org/licenses/cddl1.php","https://spdx.org/licenses/CDDL-1.0","https://spdx.org/licenses/CDDL-1.0.html","http://www.opensource.org/licenses/cddl1"],"components":["gav://org.glassfish.jersey.core:jersey-client:2.26"]},{"name":"GPL-2.0","full_name":"The GNU General Public License Version 2","more_info_url":["http://www.opensource.org/licenses/GPL-2.0","http://www.opensource.org/licenses/gpl-2.0.php","https://spdx.org/licenses/GPL-2.0","https://spdx.org/licenses/GPL-2.0.html","http://www.gnu.org/licenses/old-licenses/gpl-2.0-standalone.html"],"components":["gav://org.glassfish.jersey.core:jersey-client:2.26"]}]}]}

After:

"{\"artifacts\":[{\"general\":{\"name\":\"jersey-client-2.26.jar\",\"path\":\"doartifac/spielwiese-group-cache/org/glassfish/jersey/core/jersey-client/2.26/jersey-client-2.26.jar\",\"pkg_type\":\"Maven\",\"sha256\":\"3e44b7db8691eb0b2a6751eda888150b9ba1092a5805f11e4727fd4904407a41\",\"component_id\":\"org.glassfish.jersey.core:jersey-client:2.26\"},\"issues\":[],\"licenses\":[{\"name\":\"CDDL-1.0\",\"full_name\":\"Common Development and Distribution License (CDDL)\\n            1.0\",\"more_info_url\":[\"http://www.opensource.org/licenses/cddl1.php\",\"https://spdx.org/licenses/CDDL-1.0\",\"https://spdx.org/licenses/CDDL-1.0.html\",\"http://www.opensource.org/licenses/cddl1\"],\"components\":[\"gav://org.glassfish.jersey.core:jersey-client:2.26\"]},{\"name\":\"GPL-2.0\",\"full_name\":\"The GNU General Public License Version 2\",\"more_info_url\":[\"http://www.opensource.org/licenses/GPL-2.0\",\"http://www.opensource.org/licenses/gpl-2.0.php\",\"https://spdx.org/licenses/GPL-2.0\",\"https://spdx.org/licenses/GPL-2.0.html\",\"http://www.gnu.org/licenses/old-licenses/gpl-2.0-standalone.html\"],\"components\":[\"gav://org.glassfish.jersey.core:jersey-client:2.26\"]}]}]}"

@ernest_k Sorry, took the version from the `jersey-media-json-jackson`, now corrected. — J Fabian Meier, Nov 30 '18 at 15:55
Would be great if you could show your input and output strings — OneCricketeer, Nov 30 '18 at 15:56
What are you using to view that output? It's likely that the problem is elsewhere. The second snippet has always worked for me. — ernest_k, Nov 30 '18 at 15:56
Are you trying format already existing json string using that code? — Ulad, Nov 30 '18 at 16:02
@ernest_k That's what I tried. I am trying to get a nicely formatted json String from that ugly line of json. — J Fabian Meier, Nov 30 '18 at 16:05
@JFMeier I've just tried this with your input and it pretty-prints: `System.out.println(mapper.writerWithDefaultPrettyPrinter().writeValueAsString(mapper.readValue(json, Object.class)));` — ernest_k, Nov 30 '18 at 16:10

Ulad · Answer 1 · 2018-11-30T16:17:56.057

5

try to check this one: Convert JSON String to Pretty Print JSON output using Jackson

You need first read existing JSON to Object, then serialize it. Because now you are just serializing string.

UPD: You need to doo something like this:

ObjectMapper mapper = new ObjectMapper();
mapper.enable(SerializationFeature.INDENT_OUTPUT);

String json = "here your ugly json";
Object jsonObject = mapper.readValue(json, Object.class);

String prettyFormatted = mapper.writeValueAsString(jsonObject);

edited Nov 30 '18 at 16:17

answered Nov 30 '18 at 16:03

Ulad

1,083
8
17

This is were I got my code from. But unfortunately, it does not do what I hoped it would. – J Fabian Meier Nov 30 '18 at 16:06
@JFMeier I updated my answer, take a look, it should work – Ulad Nov 30 '18 at 16:18

PrettyPrint JSON with Jackson

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