Pretty printing JSON from Jackson 2.2's ObjectMapper

You can enable pretty-printing by setting the SerializationFeature.INDENT_OUTPUT on your ObjectMapper like so:

mapper.enable(SerializationFeature.INDENT_OUTPUT);

According to mkyong, the magic incantation is defaultPrintingWriter to pretty print JSON:

Newer versions:

System.out.println(mapper.writerWithDefaultPrettyPrinter().writeValueAsString(jsonInstance));

Older versions:

System.out.println(mapper.defaultPrettyPrintingWriter().writeValueAsString(jsonInstance));

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Seems I jumped the gun a tad quickly. You could try gson, whose constructor supports pretty-printing:

Gson gson = new GsonBuilder().setPrettyPrinting().create();
String jsonOutput = gson.toJson(someObject);

Hope this helps...

The jackson API has changed:

new ObjectMapper()
.writer()
.withDefaultPrettyPrinter()
.writeValueAsString(new HashMap<String, Object>());