How to pretty print JsonNode to JSON string using Jackson

In this short article, you will learn how to pretty-print a JsonNode object to a JSON string using the Jackson library.

Pretty print JsonNode using toPrettyString()

The simplest and straightforward way to pretty print JsonNode is using the toPrettyString() method, as shown below:

try {
    // JSON string
    String json = "{\"name\":\"John Doe\",\"email\":\"john.doe@example.com\"," +
            "\"roles\":[\"Member\",\"Admin\"],\"admin\":true,\"city\"" +
            ":\"New York City\",\"country\":\"United States\"}";

    // create object mapper instance
    ObjectMapper mapper = new ObjectMapper();

    // convert JSON string to `JsonNode`
    JsonNode node = mapper.readTree(json);

    // `JsonNode` to JSON string
    String prettyString = node.toPrettyString();

    // print pretty JSON string
    System.out.println(prettyString);

} catch (Exception ex) {
    ex.printStackTrace();
}

The above example code will output the following pretty print JSON:

{
  "name" : "John Doe",
  "email" : "john.doe@example.com",
  "roles" : [ "Member", "Admin" ],
  "admin" : true,
  "city" : "New York City",
  "country" : "United States"
}

Pretty print JsonNode using writerWithDefaultPrettyPrinter()

Another way of pretty printing JsonNode is to use the ObjectMapper class writerWithDefaultPrettyPrinter() method:

try {
    // JSON string
    String json = "{\"name\":\"John Doe\",\"email\":\"john.doe@example.com\"," +
            "\"roles\":[\"Member\",\"Admin\"],\"admin\":true,\"city\"" +
            ":\"New York City\",\"country\":\"United States\"}";

    // create object mapper instance
    ObjectMapper mapper = new ObjectMapper();

    // convert JSON string to `JsonNode`
    JsonNode node = mapper.readTree(json);

    // `JsonNode` to JSON string
    String prettyString = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(node);

    // print pretty JSON string
    System.out.println(prettyString);

} catch (Exception ex) {
    ex.printStackTrace();
}

Here is the output of the above example code:

{
  "name" : "John Doe",
  "email" : "john.doe@example.com",
  "roles" : [ "Member", "Admin" ],
  "admin" : true,
  "city" : "New York City",
  "country" : "United States"
}

Read the guide Working with Tree Model Nodes in Jackson for more JsonNode examples.

For more Jackson examples, check out the How to read and write JSON using Jackson in Java tutorial.

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