C#

public sealed class MySingleton
{
  private static MySingleton instance;
  private int i;
  private MySingleton()
  {
    i = 1;
  }
  public static MySingleton Instance // Often private, though
  {
    get
    {
      if (instance == null)
        lock (typeof(MySingleton))
          if (instance == null)
            instance = new MySingleton();
      return instance;
    }
  }
  public static int SomeMethod()
  {
    return Instance.i; // Use Instance, not instance to make sure it's init'd.
  }
}