WCF服务-实例化一个类

Question

I'm creating a WCF service (.NET 4.0/c#)... I added a new class to the project and I'm trying to instantiate it like so:

  MyNewClass inst = new MyNewClass();

... but I'm getting the famous, "Object reference not set an instance of an object" message at that line.

What could I be doing wrong?

EDIT:

Here's the class:

using System;
using bla, bla, blah...

public class MyNewClass
{
  private string cnn1 = ConfigurationManager.ConnectionStrings["connection_string_1"].ConnectionString;
  private string cnn2 = ConfigurationManager.ConnectionStrings["connection_string_2"].ConnectionString;

  public string Conn(string s)
  {
    string cnn = string.Empty;

    switch (s)
    {
      case "Server1":
        cnn = cnn1;
        break;
      case "Server2":
        cnn = cnn2;
        break;
    }

    return cnn;

  }

}

Answer 1

You should pass in a configuration object rather than calling the ConfigurationManager. That would allow you to use the class indenpendent of an appconfig / webconfig.

For instance, perhaps

public MyClass(string conn1, string conn2)
{...}

Or at least check for null before accessing a property,

For instance, change this to be in the contructor

private string cnn1;

public MyClass()
{
    if (ConfigurationManager.ConnectionStrings["connection_string_1"] != null)
    cnn1 = ConfigurationManager.ConnectionStrings["connection_string_1"].ConnectionString;
}