Pretty-Print a JSON in Java

This post will discuss how to pretty-print a JSON in Java.

1. Using GSON Library

To enable pretty-print with Gson, you can configure the Gson instance to output Json for pretty printing. The idea is to use GsonBuilder to construct a Gson instance and then invoke its setPrettyPrinting() configuration method. This is demonstrated below:

import com.google.gson.Gson;

import com.google.gson.GsonBuilder;

import java.util.List;

class Company {

public String name;

public int employees;

public List<String> offices;

public Company(String name, int employees, List<String> offices) {

this.name = name;

this.employees = employees;

this.offices = offices;

}

public class Main

{

public static void main(String[] args)

{

String jsonString = "{\"name\":\"Google\",\"employees\":140000," +

"\"offices\":[\"Mountain View\",\"Los Angeles\",\"New York\"]}";

Gson gson = new GsonBuilder().setPrettyPrinting().create();

Company company = gson.fromJson(jsonString, Company.class);

String prettyJsonString = gson.toJson(company);

System.out.println(prettyJsonString);

}

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Output:
{ "name": "Google", "employees": 140000, "offices": [ "Mountain View", "Los Angeles", "New York" ] }

Alternatively, you can use JsonParser to parse Json into a parse tree of Json elements. The parse() or parseString() method parses the specified JSON string into a parse tree, which then can be passed to the toJson() method.

import com.google.gson.Gson;

import com.google.gson.GsonBuilder;

import com.google.gson.JsonElement;

import com.google.gson.JsonParser;

public class Main {

public static void main(String[] args) {

String jsonString = "{\"name\":\"Google\",\"employees\":140000," +

"\"offices\":[\"Mountain View\",\"Los Angeles\",\"New York\"]}";

JsonParser jsonParser = new JsonParser();

JsonElement jsonElement = jsonParser.parse(jsonString);

Gson gson = new GsonBuilder().setPrettyPrinting().create();

String prettyJsonString = gson.toJson(jsonElement);

System.out.println(prettyJsonString);

}

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Output:
{ "name": "Google", "employees": 140000, "offices": [ "Mountain View", "Los Angeles", "New York" ] }

2. Using JSON-Java Library

Alternatively, if you prefer JSON-Java Library, you can use the JSONObject.toString(indentFactor) method to get a pretty-printed JSON representation of the JSONObject. A typical invocation for this method would look like this:

import org.json.JSONException;

import org.json.JSONObject;

public class Main {

public static void main(String[] args) {

String jsonString = "{\"name\":\"Google\",\"employees\":140000," +

"\"offices\":[\"Mountain View\",\"Los Angeles\",\"New York\"]}";

try {

JSONObject json = new JSONObject(jsonString);

String prettyJsonString = json.toString(4);

System.out.println(prettyJsonString);

} catch (JSONException e) {

e.printStackTrace();

}

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Output:
{ "employees": 140000, "name": "Google", "offices": [ "Mountain View", "Los Angeles", "New York" ] }

3. Using Jackson Library

The Jackson library (com.fasterxml.jackson.databind) also provides the factory method writerWithDefaultPrettyPrinter() to serialize objects with the pretty printer for indentation. Here’s how the code would look like:

import com.fasterxml.jackson.databind.ObjectMapper;

public class Main {

public static void main(String[] args) {

String jsonString = "{\"name\":\"Google\",\"employees\":140000," +

"\"offices\":[\"Mountain View\",\"Los Angeles\",\"New York\"]}";

ObjectMapper mapper = new ObjectMapper();

String prettyJsonString = mapper.writerWithDefaultPrettyPrinter()

.writeValueAsString(jsonString);

System.out.println(prettyJsonString);

}

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Output:
{ "employees": 140000, "name": "Google", "offices": [ "Mountain View", "Los Angeles", "New York" ] }

That’s all about pretty-printing a JSON in Java.

Pretty-Print a JSON in Java

1. Using GSON Library

2. Using JSON-Java Library

3. Using Jackson Library

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