8 WAYS OF CREATING INSTANCE

1. Simple with new keyword

Example1-:

public class Person

{

    public string Name;

}

Person P = new Person();

           P.Name="Deepak";

Example3-: Interface having reference of class

class Program

    {

        

       static void Main(string[] args)

        {

            IHuman P = new Person();

            P.getName();

        }

 

    }

interface IHuman

{

    void getName();

}

public class Person :IHuman

{

  

   public void getName()

   {

       Console.WriteLine("Deepak");

       Console.ReadKey();

   }

}

Example3-: Base Class having reference of derived class.

class Program

    {

        

       static void Main(string[] args)

        {

            DAD D;

            D=new Son1();

            D.getName();

            D = new Son2();

            D.getName();

            Console.ReadKey();

        }

 

    }

 public class DAD

 {

     public virtual void  getName()

     {

         Console.WriteLine("FATHER");

        

     }

 }

public class Son1 :DAD

{

  

   public override void getName()

   {

       Console.WriteLine("SON1");

      

   }

}

public class Son2:DAD

{

    public override void getName()

    {

        Console.WriteLine("SON2");

       

    }

}

2. Activator Class-:

Contains methods to create types of objects locally or remotely, or obtain references to existing remote objects. This class cannot be inherited. 

Example1-:

using System;

using System.Reflection;

using System.Text;

public class SomeType

{

    public void DoSomething(int x)

    {

        Console.WriteLine("100 / {0} = {1}", x, 100 / x);

    }

}

public class Example

{

    static void Main()

    {

        // Create an instance of the StringBuilder type using  

        // Activator.CreateInstance.

        Object o = Activator.CreateInstance(typeof(StringBuilder));

        // Append a string into the StringBuilder object and display the  

        // StringBuilder.

        StringBuilder sb = (StringBuilder) o;

        sb.Append("Hello, there.");

        Console.WriteLine(sb);

        // Create an instance of the SomeType class that is defined in this  

        // assembly.

        System.Runtime.Remoting.ObjectHandle oh =

            Activator.CreateInstanceFrom(Assembly.GetEntryAssembly().CodeBase,

                                         typeof(SomeType).FullName);

        // Call an instance method defined by the SomeType type using this object.

        SomeType st = (SomeType) oh.Unwrap();

        st.DoSomething(5);

    }

}

Example2-:

    Type T = System.Web.Compilation.BuildManager.GetCompiledType

                         ("//DynamicCompilation//Default2.aspx");

    object obj=  Activator.CreateInstance(T);

    MethodInfo m = T.GetMethod("function");

    object ret=m.Invoke(obj, null);

    Response.Write(ret.ToString());

3. Using assembly class -:Assembly.CreateInstance

Locates the specified type from this assembly and creates an instance of it using the system activator, using case-sensitive search.

Example-:

 System.Reflection.Assembly ptr =

System.Reflection.Assembly.LoadFrom("ClassLibrary1.dll");

  // get type of class test from just loaded assembly

  Type calcType = ptr.GetType("MyClass2");

    //get the method from above type

     MethodInfo m = calcType.GetMethod("AddNumb");

      //create instance of cass

       object calcInstance = ptr.CreateInstance("MyClass2");

     //invoke the method

    object str=m.Invoke(calcInstance,null);

       MessageBox.Show(str.ToString())

4. Object.MemberwiseClone Method

The MemberwiseClone method creates a shallow copy by creating a new object, and then copying the nonstatic fields of the current object to the new object. If a field is a value type, a bit-by-bit copy of the field is performed. If a field is a reference type, the reference is copied but the referred object is not; therefore, the original object and its clone refer to the same object.

Example-:

    class Program

    {

        static void Main(string[] args)

        {

            Person P = new Person();

            P.Name = "Deepak";

            Person D = P.CreateDuplicateInsatnce();

            Console.WriteLine(D.Name);

         

        }

    }

public class Person

{

   

    public string Name;

   

    public Person CreateDuplicateInsatnce()

    {

       return (Person)this.MemberwiseClone();

    }

}

 

5. Serialize and Deserialize

In simple words, we can say an object conversion in text stream is serialization and text stream creation in object of a classis called deserialization

Example-:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Runtime.Serialization.Formatters.Binary;

using System.Runtime.Serialization;

using System.IO;

    class Program

    {

        

       static void Main(string[] args)

        {

            Serialize();

            Deserialize();

        }

        static void Serialize()

        {

           Person P = new Person();

           P.Name="Deepak";

           FileStream fs = new FileStream("DataFile.dat", FileMode.Create);

           BinaryFormatter formatter = new BinaryFormatter();

           formatter.Serialize(fs, P);

           fs.Close();

        }

        static void Deserialize()

        {

            Person D = null;

            FileStream fs = new FileStream("DataFile.dat", FileMode.Open);

            BinaryFormatter formatter = new BinaryFormatter();

            D = (Person)formatter.Deserialize(fs);

            fs.Close();

            Console.WriteLine(D.Name);

            Console.ReadKey();

        }

    }

 [Serializable]

public class Person

{

    public string Name;

    public Person CreateDuplicateInsatnce()

    {

       return (Person)this.MemberwiseClone();

    }

}

6. Server.CreateObject(ASP WAY)-:

The CreateObject method creates an instance of an object. 

Example-:

<%

Set adrot=Server.CreateObject("MSWC.AdRotator")

%>

7.  ChannelFactory(WCF Way)-:

Using the ChannelFactory<T> class to make calls to your WCF services is an easier alternative to the laborious process of generating proxies via the SvcUtil tool every time a service contract changes. As its name suggests, ChannelFactory is a factory for creating service communication channels at runtime and creates object .

Example-:

 

[ServiceContract]public interface IService1{

    [OperationContract]
    string GetData(int value);

    [OperationContract]
    CompositeType GetDataUsingDataContract(CompositeType composite);

    // TODO: Add your service operations here}

BasicHttpBinding myBinding = new BasicHttpBinding();EndpointAddress myEndpoint = new EndpointAddress("http://localhost:3047/Service1.svc");ChannelFactory<IService1> myChannelFactory = new ChannelFactory<IService1>(myBinding, myEndpoint);

IService1 instance = myChannelFactory.CreateChannel();
// Call Service with new objectConsole.WriteLine(instance.GetData(10));

myChannelFactory.Close();

 8. AppDomain.CreateInstanceAndUnwrap

Creates a new instance of the specified type. Parameters specify the assembly where the type is defined, and the name of the type.
Example-:

using System;
using System.Reflection;

public class Worker : MarshalByRefObject
{
    public void PrintDomain() 
    { 
        Console.WriteLine("Object is executing in AppDomain \"{0}\"",
            AppDomain.CurrentDomain.FriendlyName); 
    }
}

class Example
{
    public static void Main()
    {
        // Create an ordinary instance in the current AppDomain
        Worker localWorker = new Worker();
        localWorker.PrintDomain();

        // Create a new application domain, create an instance 
        // of Worker in the application domain, and execute code 
        // there.
        AppDomain ad = AppDomain.CreateDomain("New domain");
        Worker remoteWorker = (Worker) ad.CreateInstanceAndUnwrap(
            Assembly.GetExecutingAssembly().FullName,
            "Worker");
        remoteWorker.PrintDomain();
    }
}