Object reference not set to an instance of an object error in json

i am trying to develop json feed below format

{
    "contacts": [
        {
                "id": "c200",
                "name": "Ravi Tamada",
                "email": "ravi@gmail.com",
                "address": "xx-xx-xxxx,x - street, x - country",
                "gender" : "male",
                "phone": {
                    "mobile": "+91 0000000000",
                    "home": "00 000000",
                    "office": "00 000000"
                }
        },
        {
                "id": "c201",
                "name": "Johnny Depp",
                "email": "johnny_depp@gmail.com",
                "address": "xx-xx-xxxx,x - street, x - country",
                "gender" : "male",
                "phone": {
                    "mobile": "+91 0000000000",
                    "home": "00 000000",
                    "office": "00 000000"
                }
        },


  ]
}

using below codes 

public class Phone
{
    public string mobile { get; set; }
    public string home { get; set; }
    public string office { get; set; }
}

public class Cont
{
    public string sno { get; set; }
    public string name { get; set; }
    public string em { get; set; }
    public string address { get; set; }
    public string gender { get; set; }
    public Phone phone { get; set; }
}

public class RootObject
{
    public List<Cont> contacts { get; set; }
}

and 

var objectToSerialize = new RootObject();
      //  var aa = new Cont();
        objectToSerialize.contacts = new List<Cont> 
                          {
                             new Cont { sno = "test1", name = "index1" , address = "index1",gender="male",em="scd", phone={mobile="ff",home="ff",office="ff"}}
                           //  new Item { name = "test2", index = "index2" }
                          };

        JavaScriptSerializer serializer = new JavaScriptSerializer();
        Response.Write(serializer.Serialize(objectToSerialize));

using this code unable to get my output ,i am also getting Object reference not set to an instance ..

i have added my all code .

any one help what is wrong in my code

Jon Skeet
people
quotationmark

This is the problem, in your object initializer:

phone={mobile="ff",home="ff",office="ff"}

That's trying to set properties of an existing Phone object. In other words, it's performing:

var tmp = new Cont();
tmp.sno = "test1";
...
tmp.phone.mobile = "ff";
tmp.phone.home = "ff";
...

... without ever setting the value of tmp.phone to a non-null reference.

You either want:

phone=new Phone {mobile="ff",home="ff",office="ff"}

Or you need to change your Cont class to give it a constructor to initialize Phone:

public Cont()
{
    phone = new Phone();
}

I'd also strongly advise you to follow .NET naming conventions for your properties, and give your class a full name of Contact rather than Cont. Avoid abbreviating pointlessly.

You should be able to configure the serializer to use lower-case names in the JSON without making the .NET names ugly.

people

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