- Does the `java.util.UUID` is unique in each file?

For example:

* We have file **IDFile1.java**, generating here a random id, using `UUID.randomUUID().toString()`.
* And we have file2 with name **IDFile2.java**, which generates another id.

Will this two file IDs collide with each other?

- Is there any way to "turn back" used ID, generated from `java.util.UUID`, that will mean, this ID could be used again?