listiterator

I'm currently trying to learn how to implement my own ListIterators. I have most of it implemented and ready to go, except I'm confused by the previous() method. By standard convention, can I get an explanation of how previous() is usually interpreted. i.e.: >cursor< dog cat fish bird frog snake According to Oracles Java Platform 7 API: E previous() Returns the previous element in the list and moves the cursor position backwards. This method may be called repeatedly to iterate through the list backwards, or intermixed with calls to next() to go back and forth. (Note that alternating calls to

I'm trying to remove an object from a list using the list iterator. I've gone through the other solutions on the website and none have alleviated the error "Exception in thread "main" java.util.ConcurrentModificationException" here is my code that is not executing : void PatronReturn(String bookName) { // get to beginning while(listIterator.hasPrevious()) { listIterator.previous(); } while(listIterator.hasNext()){ Book b = listIterator.next(); if (listIterator.next().getBookTitle().equals(bookName)) { //listIterator.next(); //listIterator.remove(); books.remove(b); //listIterator.next(); /

Option 1: Make a list which implements Comparable and sort it using collections.sort(List l) every time you add a value. Option 2: Make a TreeSet (which keeps itself sorted all the time). Which one will be faster? I am asking this because List gives me the option of ListIterator which I need in my case, since it lets me add an element while iterating. The most important differences: Criterion | List with Collections.sort | TreeSet ----------------+----------------------------+--------- cost of adding | O(n log n) | O(log n) equal sort keys | permitted | eliminated as duplicates iteration |

I was using iterator for ArrayList as : List<String> al = new ArrayList<>(); // ----- Logic for adding elements----- Iterator it = al.iterator(); // logic to retrieve elements---- Then it tried to work on ListIterator, like this . ListIterator li = al.listIterator(); while(li.hasNext()) { System.out.print(li.next()+" "); } It Worked ... I tried this for backward retrieval ListIterator li = al.listIterator(); while(li.hasPrevious()) { System.out.print(li.previous()+" "); } But its not working. The below code is working. ListIterator<String> li = al.listIterator(al.size()); while(li.hasPrevious(

Lets have a look at this example: public class ListIteratorTest { public static void main(String[] args) { List<String> list = new ArrayList<>(); list.add("element1"); list.add("element2"); list.add("element3"); list.add("element4"); ListIterator<String> iterator = list.listIterator(); } } And now, this works fine: // prints elements out, and then appropriately removes one after another while (iterator.hasNext()){ System.out.println(iterator.next()); iterator.remove(); } while this throws an IllegalStateException: // throws IllegalStateException, why? iterator.forEachRemaining(n -> { System

I have the following code which throws ConcurrentModificationException because I am using two different iterators on the same list and one of them is modifying the list. So, the second iterator throws the exception when reading the list because some other iterator has modified the list. List<Integer> list = new ArrayList<>(); populate(list);//A method that adds integers to list ListIterator<Integer> iterator1 = list.listIterator(); ListIterator<Integer> iterator2 = list.listIterator(); while (iterator1.hasNext()) { if(iterator1.next() < 5) iterator1.remove(); } while (iterator2.hasNext()){ if

Possible Duplicate: Java: adding elements to a collection during iteration My problem is that I want to expand a list with new elements while iterating over it and I want the iterator to continue with the elements that I just added. From my understanding the ListIterator.add() adds an element before the current element in the list, not after it. Is it possible to achieve this in some other way? You can't modify a Collection while iterating over it using an Iterator , except for Iterator.remove() . However, if you use the listIterator() method, which returns a ListIterator , and iterate over