Collections 3

import java.util.ArrayList;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.ListIterator;

public class Main {
    public static void main(String[] args) {
        ArrayList<String> arrayList = new ArrayList<>();
        LinkedList<String> linkedList = new LinkedList<>();

        for (int i = 0; i < 10; i++) {
            arrayList.add("num_" + i);
            linkedList.add("num_" + i);
        }

        System.out.println("First step:");
        System.out.print("\tArray List: \n\t\t");
        printElements(arrayList.iterator());
        System.out.print("\tLinked List: \n\t\t");
        printElements(linkedList.iterator());

        ListIterator arrayIterator = arrayList.listIterator();
        ListIterator linkedIterator = linkedList.listIterator();

        while (linkedIterator.hasNext()) {
            if (arrayIterator.hasNext()) {
                linkedIterator.add(arrayIterator.next());
            }
            linkedIterator.next();
        }

        System.out.println("Second step:");
        System.out.print("\tArray List: \n\t\t");
        printElements(arrayList.iterator());
        System.out.print("\tLinked List: \n\t\t");
        printElements(linkedList.iterator());

        arrayIterator = arrayList.listIterator();
        while (linkedIterator.hasPrevious()) {
            linkedIterator.previous();
            if (arrayIterator.hasNext()) {
                linkedIterator.add(arrayIterator.next());
            }
            linkedIterator.previous();
            linkedIterator.previous();
        }

        System.out.println("Third step:");
        System.out.print("\tArray List: \n\t\t");
        printElements(arrayList.iterator());
        System.out.print("\tLinked List: \n\t\t");
        printElements(linkedList.iterator());
    }

    public static void printElements(Iterator iterator) {
        while (iterator.hasNext()) {
            System.out.print(iterator.next() + " ");
        }
        System.out.println();
    }
}