How to get data from the above webservice method an android

Question

[WebMethod]

public string Grade()

{

DataTable dt = new DataTable();

dt = ConnectionClass.Selectcommand("select ProductName,PurchasePrice from Product");

resultC res = new resultC { result = dt };

string json = JsonConvert.SerializeObject(res);

return json;

}

 

How to get data from the above webservice method an android using Soap Method. please, help me