How to parse a JSON to Gson Tree Model in Java?

Sometimes, we may need to parse a JSON into a Gson tree model in Java. For example, we may need to parse a JSON string into a tree model when we want to manipulate the JSON data in a more easy way.

The getAsJsonObject() Method

The Gson library is used to parse a JSON String into a Tree Model. We will be using the JsonParser to parse the JSON string into a Tree Model of type JsonElement.

We will be using the getAsJsonObject() method of JsonElement for getting the element as JsonObject, and the other is getAsJsonArray(), which is a method of JsonElement that can be used to get the element as JsonArray.

In this article, we will learn how to parse a JSON to a Gson tree model in Java. But before that, add the Gson library to the project. If you are using Maven, add below to your pom.xml file:

<dependency>
   <groupId>com.google.code.gson</groupId>
   <artifactId>gson</artifactId>
   <version>2.8.9</version>
</dependency>

If you do not use Maven, you can download the jar file from here.

Steps to Parse a JSON to a Gson Tree Model

The following are the steps to parse a JSON to a Gson tree model in Java:

• Import the Gson library as above.
• Create a JSON string.
• Use the JsonParser class to read the JSON string and turn it into a JsonElement.
• Convert the JsonElement into a JsonObject using the getAsJsonObject() method.
• Use the getAsJsonArray() method to turn the JsonElement into a JsonArray.
• Finally, display the JsonObject and JsonArray to see the results.

Example

Following is the code to parse a JSON to a Gson tree model in Java:

import com.google.gson.*;

public class ParseJsonToGsonTreeModelExample {
   public static void main(String[] args) {
      // JSON string to be parsed
      String jsonString = "{"name":"Ansh","age":23,"skills":["Java","Python"]}";
      // Create a JsonParser object
      JsonParser jsonParser = new JsonParser();
      // Parse the JSON string to a JsonElement
      JsonElement jsonElement = jsonParser.parse(jsonString);
      // Get the element as a JsonObject
      JsonObject jsonObject = jsonElement.getAsJsonObject();
      // Get the element as a JsonArray
      JsonArray jsonArray = jsonObject.getAsJsonArray("skills");
      // Print the JsonObject and JsonArray
      System.out.println("JsonObject: " + jsonObject);
      System.out.println("JsonArray: " + jsonArray);
   }
}
class Person {
   private String name;
   private int age;

   public Person(String name, int age) {
      this.name = name;
      this.age = age;
   }

   public String getName() {
      return name;
   }

   public int getAge() {
      return age;
   }
}

Output

The output of the above code will be:

JsonObject: {"name":"Ansh","age":23,"skills":["Java","Python"]}
JsonArray: ["Java","Python"]