问题
I work with DefaultMutableTreeNode, and it has methods depthFirstEnumeration(), breadthFirstEnumeration() and children() that return Enumeration of tree nodes.
I need to use the returned Enumeration multiple times, but I can't find any method like reset() in Enumeration. It seems like I only can get all the elements just once, and then call depthFirstEnumeration() again to get new Enumeration, it seems not to be a good solution.
Of course, I can get all the elements from Enumeration and convert it to any another reusable representation, but is there really a way to use Enumeration multiple times?
回答1:
No that is not possible with Enumeration. On this subject, java doc says:
An object that implements the Enumeration interface generates a series of elements, one at a time.
Notice the one at a time which means that if you want to manipulate the Enumeration as a list then you will have to convert it.
You can create a List when you first request the Enumeration. This way you could use and manipulate it however you wish.
Enumeration e = ...
ArrayList aList = Collections.list(e);
来源：https://stackoverflow.com/questions/10460534/java-use-enumeration-multiple-times