A Simple Json Utility Class Using Gson

In my current project we planned to go with Gson(Google's json manipulating library) to handle out json manipulation within our application. Hence i wrote this small utility class to ease the use of Gson within the project.

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

/**
 * This class is used as a Json utility. The base functionality comes from the Gson<br>
 * package from Google. It is made generic due to the fact that many clients may use<br>
 * this class at any given moment.
 * 
 * @author dinuka
 * @param <T>
 */
public class Jsonutil {

    /**
     * Null serialize is used because else Gson will ignore all null fields.
     */
    private static Gson gson = new GsonBuilder().serializeNulls().create();

    /**
     * Made private because all methods are static and hence do not need
     * object instantiation
     */
    private Jsonutil() {}
    /**
     * To Json Converter using Goolge's Gson Package<br>
     * this method converts a simple object to a json string<br>
     * 
     * @param obj
     * @return a json string
     */
    public static <T> String toJsonObj(T obj) {
        return gson.toJson(obj);
    }

    /**
     * Converts a collection of objects using Google's Gson Package
     * 
     * @param objCol
     * @return a json string array
     */
    public static <T> String toJsonList(List<T> objCol) {
        return gson.toJson(objCol);
    }

    /**
     * Returns the specific object given the Json String
     * @param <T>
     * @param jsonString
     * @param obj
     * @return a specific object as defined by the user calling the method
     */
    public static <T> T fromJsonToObj(String jsonString,Class<T>obj) {
        return gson.fromJson(jsonString, obj);
    }
    
    /**
     * Returns a list of specified object from the given json array
     * @param <T>
     * @param jsonString
     * @param t the type defined by the user
     * @return a list of specified objects as given in the json array
     */
    public static <T> List<T> fromJsonToList(String jsonString,Type t){ 
        return gson.fromJson(jsonString, t);
    }

}

Typical usage of the given utility class is as follow;

import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.List;

import com.google.gson.reflect.TypeToken;


public class Test {

    
    public static void main(String[] args) {    
        Person p = new Person();
        p.setFirstName("xxx");
        p.setLastName("yyy");
        
        List<Person>pList = new ArrayList<Person>();
        pList.add(p);
        
        String jsonStr = JsonUtil.toJsonList(pList);
        
        System.out.println("Person List as Json Array = "+jsonStr);
        
        Type collectionType = new TypeToken<List<Person>>(){}.getType();
        List<Person>personList =  JsonUtil.fromJsonToList(jsonStr,collectionType);
        System.out.println("Person List from json String array = "+personList);
        
        String personJsonStr = JsonUtil.toJsonObj(p);
        System.out.println("Json String from person = "+personJsonStr);
        
        Person p1 = JsonUtil.fromJsonToObj(personJsonStr, Person.class);
        System.out.println("Person from json String = "+p1);
        
    }
    
    

}

class Person{
    private String firstName;
    private String lastName;
    /**
     * @return the firstName
     */
    public String getFirstName() {
        return firstName;
    }
    /**
     * @param firstName the firstName to set
     */
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }
    /**
     * @return the lastName
     */
    public String getLastName() {
        return lastName;
    }
    /**
     * @param lastName the lastName to set
     */
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
    /* (non-Javadoc)
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        return "Person [firstName=" + firstName + ", lastName=" + lastName + "]";
    }
    
    
}

Thats it guys. If you have any queries or possible enhancements you can see, please do leave a comment.