JSONはGsonを使用してJsonの文字列に変換

Userクラス:

package creater_gson;

import java.util.ArrayList;
import java.util.HashMap;

/*
 *      Class 
 * 
 * */
public class User {
	public int id;
	public String Name;
	public int age;
	public String email;
}

Testクラス:

package creater_gson;

import com.google.gson.Gson;

/*
 *  Java Class    Gson   Json    
 *               
 * 
 * */
public class UserTest {
	public static void main(String [] args){
	Gson gson = new Gson();
	User user = new User();
	
	user.id = 1;
	user.Name = "   ";
	user.age = 22;
	user.email = "[email protected]";
		
	System.out.println("  JSON  ：" + gson.toJson(user));
	
    }
}