How to Convert Map to JSON in Java using Gson API

on December 2, 2016

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Convert Map to JSON in Java

Simple example about, How to Convert Map to JSON in Java using Gson API.

Item.java

package com.dineshkrish.json;
public class Item {
private int itemId;
private String itemName;
private String itemDesc;
public Item(int itemId, String itemName, String itemDesc) {
this.itemId = itemId;
this.itemName = itemName;
this.itemDesc = itemDesc;
}
public int getitemId() {
return itemId;
}
public String getitemName() {
return itemName;
}
public String getitemDesc() {
return itemDesc;
}
}

MapConversion.java

package com.dineshkrish.json;
import java.util.HashMap;
import java.util.Map;
import com.google.gson.Gson;
public class MapConversion {
public static void main(String[] args) {
// Defining Gson Object
Gson gson = new Gson();
// Defining Map Object
Map<Integer, Item> itemMap = new HashMap<Integer, Item>();
// Adding elements to Map
itemMap.put(101, new Item(101, "Java", "Java Language"));
itemMap.put(102, new Item(101, "C", "C Language"));
itemMap.put(103, new Item(101, "Python", "Python Language"));
itemMap.put(104, new Item(101, "Ruby", "Ruby Language"));
itemMap.put(105, new Item(101, "Php", "PHP Language"));
// Convert Map to Json
String jsonString = gson.toJson(itemMap);
System.out.println(jsonString);
}
}

Output

{“102”:{“itemId”:101,”itemName”:”C”,”itemDesc”:”C Language”},”103″:{“itemId”:101,”itemName”:”Python”,”itemDesc”:”Python Language”},”101″:{“itemId”:101,”itemName”:”Java”,”itemDesc”:”Java Language”},”104″:{“itemId”:101,”itemName”:”Ruby”,”itemDesc”:”Ruby Language”},”105″:{“itemId”:101,”itemName”:”Php”,”itemDesc”:”PHP Language”}}