http://msdn.microsoft.com/en-us/library/ms998558.aspx
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
using System;
public sealed class Singleton
{
private static volatile Singleton instance;
private static object syncRoot = new Object();
private Singleton() {}
public static Singleton Instance
{
get
{
if (instance == null)
{
lock (syncRoot)
{
if (instance == null)
instance = new Singleton();
}
}
return instance;
}
}
}
public sealed class Singleton
{
private static volatile Singleton instance;
private static object syncRoot = new Object();
private Singleton() {}
public static Singleton Instance
{
get
{
if (instance == null)
{
lock (syncRoot)
{
if (instance == null)
instance = new Singleton();
}
}
return instance;
}
}
}