java SE复习笔记37

单例模式：懒汉式(可能存在线程安全问题)
public class TestSingleton{
public static void main(String[] args){

}
}
class Singleton{
private static Singleton instance = null;
private Singleton(){}
public static Singleton getInstance(){
if(instance == null)
instance = new Singleton();
return instance;
}
}