EJ.03 用私有构造器或者枚举类型强化Singleton属性// Enum singleton - the preferred approachpublic enu
EJ.03 用私有构造器或者枚举类型强化Singleton属性
// Enum singleton - the preferred approachpublic enum Elvis { INSTANCE; public void leaveTheBuilding() { ... }}?
EJ.03 用私有构造器或者枚举类型强化Singleton属性
// Enum singleton - the preferred approachpublic enum Elvis { INSTANCE; public void leaveTheBuilding() { ... }}?