Design Mode Study Note 2-singleton Mode

Intention : For some purpose (such as performance considerations and logic requirements), only N instances of the same class can be created.

Application: Abstract Factory classes and object pools in factory Mode

Namespace Designpattern. Singleton
{
// Single thread
Public   Class Singlethread
{
Private   Static Singlethread instance;

Private Singlethread ()
{
}

Public   Static Singlethread instance
{
Get
{
If (Instance =   Null )
{
Instance= NewSinglethread ();
}
Return Instance;
}
}

// The. NET static Object Instantiation mechanism is implemented with the following code line. This method is simple, but cannot be initialized in the constructor. Of course, you can call a custom method for initialization.
// Public static readonly singlethread instance = new singlethread ();
}

// Multithreading
Public   Class Multithread
{
Private   Static   Volatile Multithread instance;
Private   Static   Object OBJ =   New   Object ();

Private Multithread ()
{
}

Public   Static Multithread instance
{
Get
{
If (Instance =   Null )
{
Lock (OBJ)
{
If (Instance =   Null )
{
Instance= NewMultithread ();
}
}
}
Return Instance;
}
}
}
}