How can we parse a nested JSON object in Java?

The JSON is a lightweight, text-based and language-independent data exchange format. The JSON can represent two structured types like objects and arrays. A JSONArray can parse text from a String to produce a vector-like object. We can parse a nested JSON object using the getString(index) method of JSONArray. This is a convenience method for the getJSONString(index).getString() method and it returns a string value at the specified position.

Syntax

String getString(int index)

Example

import java.util.*;
import org.json.*;
public class NestedJSONObjectTest {
   public static void main(String args[]) {
      String jsonDataString = "{userInfo : [{username:abc123}, {username:xyz123},{username:pqr123},   {username:mno123},{username:jkl123}]}";
      JSONObject jsonObject = new JSONObject(jsonDataString);
      List<String> list = new ArrayList<String>();
      JSONArray jsonArray = jsonObject.getJSONArray("userInfo");
      for(int i = 0 ; i < jsonArray.length(); i++) {
         list.add(jsonArray.getJSONObject(i).getString("username"));
         System.out.println(jsonArray.getJSONObject(i).getString("username")); // display usernames
      }
   }
}

Output

abc123
xyz123
pqr123
mno123
jkl123