Well, simplest answer is “there is no need to do it“. Extending an interface simply means that you are creating a subtype of interface, in other words a more specialized behavior and Collection interface is not expected to do what Cloneable and Serializable INTERFACES do.

ANOTHER reason is that not EVERYBODY will have a reason to have Cloneable collection because if it has very large data, then every unnecessary clone operation will consume a big memory. Beginners might use it without KNOWING the CONSEQUENCES.

Another reason is that Cloneable and Serializable are very specialized behavior and so should be implemented only when required. For example, many concrete classes in collection implement these interfaces. So if you want this feature. use these collection classes otherwise use their alternative classes.

Well, simplest answer is “there is no need to do it“. Extending an interface simply means that you are creating a subtype of interface, in other words a more specialized behavior and Collection interface is not expected to do what Cloneable and Serializable interfaces do.

Another reason is that not everybody will have a reason to have Cloneable collection because if it has very large data, then every unnecessary clone operation will consume a big memory. Beginners might use it without knowing the consequences.

Another reason is that Cloneable and Serializable are very specialized behavior and so should be implemented only when required. For example, many concrete classes in collection implement these interfaces. So if you want this feature. use these collection classes otherwise use their alternative classes.