Iterator & Enumeration

[Shyam Hai]

what is the difference between

Iterator & Enumeration..

Please........

[Muhammad Khojaye]

Ragavendran Sivaji Rao wrote:
what is the difference between

Iterator & Enumeration..

Please........

In Java 5 and above you have use foreach loop on anything that implements Iterable:

for (Object o : list) {
do(o);
}

You can iterate over an Enumeration even it does not implement Iterable.

Iterable is a factory method for Iterator. Enumeration is similar to Iterator, and only maintains state for a single enumeration. So, be careful trying to wrap an Enumeration as an Iterable. If someone passes me an Iterable, I will assume that I can repeatedly call iterator on it, creating as many Iterators as I want, and iterating independently on each. A wrapped Enumeration will not fulfill this contract; don't let your wrapped Enumeration escape from your own code.
Enumeration is like an Iterator, not an Iterable. A Collection is Iterable. An Iterator is not.

[Campbell Ritchie]

Have you read the API documentation for Enumeration and Iterator?

[Rob Spoor]

There are two major differences between the Enumeration and Iterator interfaces:
- Iterator has a remove() method
- the names of the methods in Iterator are a lot shorter

For the rest, they are quite the same, also in use: while there are more elements, get the next element and handle it. In code:

while (iterator.hasNext()) // or enumeration.hasMoreElements()
{
    Object object = iterator.next(); // or enumeration.nextElement()
    ...
    if (someCondition)
    {
        iterator.remove(); // no equivalent in Enumeration
    }
}