Java: why can’t iterate over an iterator?

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Most likely the reason for this is because iterators are not reusable; you need to get a fresh Iterator from the Iterable collection each time you want to iterate over the elements. However, as a quick fix:

private static <T> Iterable<T> iterable(final Iterator<T> it){
     return new Iterable<T>(){ public Iterator<T> iterator(){ return it; } };
}

//....
{
     // ...
     // Now we can use:
     for ( X x : iterable(it) ){
        // do something with x
     }
     // ...
}
//....

That said, the best thing to do is simply pass around the Iterable<T> interface instead of Iterator<T>

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