How to enable pretty print JSON with Jackson

In Jackson, we can use writerWithDefaultPrettyPrinter() to pretty print the JSON strings.

Table of contents:

• 1. Setup Jackson
• 2. Compact print JSON (Default)
• 3. Pretty print JSON with Jackson
• 4. Pretty print JSON with Jackson (Globally)
• 5. Download Source Code
• 6. References

P.S Tested with Jackson 2.17.0

1. Setup Jackson

Puts jackson-databind at pom.xml.

  <dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.17.0</version>
  </dependency>

2. Compact print JSON (Default)

By default, Jackson prints JSON strings in compact format:

package com.mkyong.json.jackson.tips;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.mkyong.json.model.Person;

public class PrettyPrintJsonExample {

    public static void main(String[] args) throws JsonProcessingException {

        ObjectMapper mapper = new ObjectMapper();
        Person person = new Person("mkyong", 42);

        String json = mapper.writeValueAsString(person);
        System.out.println(json);

    }
}

Output

{"name":"mkyong","age":42}

3. Pretty print JSON with Jackson

We can use .writerWithDefaultPrettyPrinter() to manually enable the pretty print JSON strings.

	ObjectMapper mapper = new ObjectMapper();

	// enable pretty print
	mapper.writerWithDefaultPrettyPrinter().writeValueAsString(...)

package com.mkyong.json.jackson.tips;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.mkyong.json.model.Person;

public class PrettyPrintJsonExample {

    public static void main(String[] args) throws JsonProcessingException {

        ObjectMapper mapper = new ObjectMapper();
        Person person = new Person("mkyong", 42);

        String json = mapper
                .writerWithDefaultPrettyPrinter() // enable pretty print
                .writeValueAsString(person);
        System.out.println(json);

    }
}

Output

{
  "name" : "mkyong",
  "age" : 42
}

4. Pretty print JSON with Jackson (Globally)

We can enable the SerializationFeature.INDENT_OUTPUT feature in the ObjectMapper. This will enable the pretty print JSON globally.

package com.mkyong.json.jackson.tips;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.mkyong.json.model.Person;

public class PrettyPrintJsonExample {

    public static void main(String[] args) throws JsonProcessingException {

        ObjectMapper mapper = new ObjectMapper();

        // enable the pretty print globally
        mapper.enable(SerializationFeature.INDENT_OUTPUT);

        Person person = new Person("mkyong", 42);

        String json = mapper.writeValueAsString(person); // compact-print

        System.out.println(json);

    }
}

Output

{
  "name" : "mkyong",
  "age" : 42
}

5. Download Source Code

6. References

• Jackson Github
• Jackson data-binding
• Jackson Convert Java Object to / from JSON
• How to parse JSON string with Jackson