Is there a writable iterator in Java?

问题

In C+ one can use iterators for writing to a sequence. Simplest example would be:

vector<int> v;
for (vector<int>::iterator it = v.begin(); it!=v.end(); ++it) {
    *it = 42;
}

I need something more complicated - keep iterator as a class member for a later use. But I don't know how to get this behavior from Java iterators.

Are there writable iterators in Java at all?
If not then what replaces them?

回答1:

The ListIterator (which you can obtain by List#listIterator()) has add() and set() methods which allows you to respectively insert and replace the item at the currently iterated index. That's as far the only "writable iterator" as I can think of in Java.

_{Not sure though if that is the exact replacement of the given C++ code since I don't know C++.}

回答2:

As arrays can be accessed directly and quickly by their index, you don't really need an iterator object. Wouldn't it be enought to save the index of the array in that class member? This would permit to read and write the value of the array.

PS: You could use an ArrayList, which is an automatically growing set of arrays and use the ListIterator as Balus described in order to use the iterator-object-approach.

回答3:

Looks more like you want a List (or maybe some other collection, like Set) or an array.

Also, you could just make your contents mutable. It looks silly for integers, but continuing your example

for (MutableInteger i : CollectionOfMInts) i.setTo(42);

来源：https://stackoverflow.com/questions/2802571/is-there-a-writable-iterator-in-java

标签

java

arrays

iterator

mutable