Singleton design pattern
S ingleton pattern is a design solution where an application wants to have one and only one instance of any class.It saves memory because object is not created with each request. Only single instance is reused again and again. But how to make any class singleton is not so easy task, because there are several way in which singleton can break. Steps: 1. Make constructor private, so not directly instantiated class 2. Make a static method which produce existing instance if one available else new 3. Override clone() method. One cannot create a cloned object which also violates singleton pattern. 4. If Singleton is class is serializable then once it serialized again deserialized it, but it will not return singleton object.
