双重锁定的单例种
双重锁定的单例类
public class Singleton { private static Singleton instance; private static Object syncRoot = new Object(); private Singleton() {} public static Singleton getInstance(){ if(instance == null){ synchronized (syncRoot) { if(instance == null){ instance = new Singleton(); } } } return instance; }
线程安全下的单例类 ,双重锁定哦