Tags: Gson , JSON

Following code snippet shows how you can convert Java object to JSON string and vice versa.

Source code (Item.java)

public class Item {

    private Long id;
    private String name;
    private Double price;

    public Item() {
    }
    
    public Item(String name, Double price) {
        this.name = name;
        this.price = price;
    }
    
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }
    
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Double getPrice() {
        return price;
    }

    public void setPrice(Double price) {
        this.price = price;
    }
    
    @Override
    public String toString() {
        return "Item{" + "name=" + name + ", price=" + price + '}';
    }
}

Source code (ObjectToJSON.java)

import com.google.gson.Gson;
import com.javaquery.bean.Item;
import java.util.Arrays;
import java.util.List;

/**
 * Convert Java object to json using gson.
 * @author javaQuery
 * @date 24th March, 2017
 * @Github: https://github.com/javaquery/Examples
 */
public class ObjectToJSON {
    public static void main(String[] args) {
        /* Java object */
        Item iPhone = new Item("iPhone 7", 100.12);
        Item blackBerry = new Item("Black Berry", 50.12);
        List<Item> items = Arrays.asList(iPhone, blackBerry);
        
        Gson gson = new Gson();
        
        /* Convert single Object to JSON */
        String jsonObjectString = gson.toJson(iPhone);
        System.out.println(jsonObjectString);
        
        /* Convert List of Object to JSON */
        String jsonArrayString = gson.toJson(items);
        System.out.println(jsonArrayString);
    }
}

Output

{"name":"iPhone 7","price":100.12}
[{"name":"iPhone 7","price":100.12},{"name":"Black Berry","price":50.12}]

Source code (JSONToObject.java)

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import com.javaquery.bean.Item;
import java.lang.reflect.Type;
import java.util.List;

/**
 * Convert json string to java object using gson.
 * @author javaQuery
 * @date 24th March, 2017
 * @Github: https://github.com/javaquery/Examples
 */
public class JSONToObject {
    public static void main(String[] args) {
        String jsonObjectString = "{\"name\":\"iPhone 7\",\"price\":100.12}";
        String jsonArrayString = "[{\"name\":\"iPhone 7\",\"price\":100.12},{\"name\":\"Black Berry\",\"price\":50.12}]";
        
        Gson gson = new Gson();
        
        /* Convert JSONObject String to Object */
        Item item = gson.fromJson(jsonObjectString, Item.class);
        System.out.println(item);
        
        /* Convert JSONArray String to Object */
        Type type = new TypeToken<List<Item>>(){}.getType();
        List<Item> items = gson.fromJson(jsonArrayString, type);
        System.out.println(items);
    }
}

Output

Item{name=iPhone 7, price=100.12}
[Item{name=iPhone 7, price=100.12}, Item{name=Black Berry, price=50.12}]

Tags: Gson , JSON