Difference between Close() and Dispose() Method

The basic difference between Close() and Dispose() is, when a Close() method is called, any managed resource can be temporarily closed and can be opened once again. It means that, with the same object the resource can be reopened or used. Where as Dispose() method permanently removes any resource ((un)managed) from memory for cleanup and the resource no longer exists for any further processing.

Example showing difference between Close() and Dispose() Method:


using System;
using System.Data;
using System.Data.SqlClient;
public class Test
{
private string connString = "Data Source=COMP3;Initial Catalog=Northwind;User Id=sa;Password=pass";
private SqlConnection connection;
public Test()
{
connection = new SqlConnection(connString);
}
private static void Main()
{
Test t = new Test();
t.ConnectionStatus();
Console.ReadLine();
}
public void ConnectionStatus()
{
try
{
if(connection.State == ConnectionState.Closed)
{
connection.Open();
Console.WriteLine("Connection opened..");
}

if(connection.State == ConnectionState.Open)
{
connection.Close();
Console.WriteLine("Connection closed..");
}
// connection.Dispose();

if(connection.State == ConnectionState.Closed)
{
connection.Open();
Console.WriteLine("Connection again opened..");
}
}
catch(SqlException ex)
{
Console.WriteLine(ex.Message+"\n"+ex.StackTrace);
}
catch(Exception ey)
{
Console.WriteLine(ey.Message+"\n"+ey.StackTrace);
}
finally
{
Console.WriteLine("Connection closed and disposed..");
connection.Dispose();
}
}
}

In the above example if you uncomment the "connection.Dispose()" method and execute, you will get an exception as, "The ConnectionString property has not been initialized.".This is the difference between Close() and Dispose().