Break singleton pattern

What are the different ways we can break a singleton pattern in Java?

• Use reflection to access the private constructor and instantiate the class as many times as you want.(can prevent using early initialization)

• Serialization. If you do not implement readResolve then reading a singleton with

          ObjectInputStream.readObject() will return a new instance of this singleton.

• Clone() :Preferred way is not to implement Cloneable interface.