关于volatile变量

mousepc

今天看到了一个单例模式代码：

public class Singleton{private volatile static Singleton uniqueInstance;private Singleton(){}public static Singleton getInstance(){if (uniqueInstance == null){synchronized (Singleton.class){if (uniqueInstance == null){uniqueInstance = new Singleton();}}}return uniqueInstance;}} 看到了一个关键字：volatile，由于自己不理解，上网查了一下。
http://www.ibm.com/developerworks/cn/java/j-jtp06197.html
http://blog.21ic.com/user1/2949/archives/2007/35599.html