CODEWITHSUNDEEP
javaiterator
Eko
Eko

Reputation: 1557

Rewind iterator

I'm making a game using Libgdx. In my main loop, I use an iterator to iterate through all the elements of my world. My World class look like this :

public class World implements Iterable<GameElement>
{
    ...
    public Iterator<GameElement> iterator()
    {
        return listGameElements.iterator();
    }
}

But when I profile my application, there is a lot of allocations coming from the line listGameElements.iterator() (this line is called at every game loop, so a lot of times in a second).

I wanted to put my iterator as an private attribute of my class, but the iterator can be used only one time. Is there a way to rewind an iterator, to avoid making more allocations?

Upvotes: 1

Views: 2042

Answers (1)

Al&#233;cio Carvalho
Al&#233;cio Carvalho

Reputation: 13657

You can do it based on the ListIterator it allows you to go in both directions.

Example of usage:

aList.add("1");
aList.add("2");
aList.add("3");
aList.add("4");
aList.add("5");

ListIterator listIterator = aList.listIterator();

System.out.println("moving forward");
while(listIterator.hasNext()) {
  System.out.println(listIterator.next());
}

System.out.println("moving backward");
while(listIterator.hasPrevious()) {
  System.out.println(listIterator.previous());
}

Upvotes: 4

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