设计模式之单例模式

好的设计模式分享//单例模式//饿汉（开发常用）class A {private static A a = new A();private A() {}public static A getInstance() {return a;}}//懒汉（笔试常用）class A {private static A a = null;private A() {}public static synchronized A getInstance() {if (a == null)a = new A();return a;}}