List Iterator : Iterator « Collections Data Structure « Java

List Iterator

List Iterator

public class ListIterator {
  private Link current; 

  private Link previous;

  private LinkList ourList;

  public ListIterator(LinkList list) {
    ourList = list;
  //   start at 'first'
  public void reset() {
    current = ourList.getFirst();
    previous = null;

  public boolean atEnd() {
    return ( == null);

  //   go to next link
  public void nextLink() {
    previous = current;
    current =;

  public Link getCurrent() {
    return current;

  public void insertAfter(long dd) {
    Link newLink = new Link(dd);

    if (ourList.isEmpty()) {
      current = newLink;
    } else // not empty
    { =; = newLink;
      nextLink(); // point to new link

  public void insertBefore(long data) {
    Link newLink = new Link(data);
    if (previous == null) { = ourList.getFirst();
    }// not beginning
    else { =; = newLink;
      current = newLink;

  //   delete item at current
  public long deleteCurrent() {
    long value = current.dData;
    //     beginning of list
    if (previous == null) {
    }// not beginning
    else { =;
      if (atEnd())
        current =;
    return value;

  public static void main(String[] args) throws IOException {
    LinkList theList = new LinkList(); 
    ListIterator iter1 = theList.getIterator(); 
    long value;


    if (!theList.isEmpty())
      System.out.println("List is empty");

class LinkList {
  private Link first;

  public LinkList() {
    first = null;

  public Link getFirst() {
    return first;

  public void setFirst(Link f) {
    first = f;

  public boolean isEmpty() {
    return first == null;

  public ListIterator getIterator() {
    return new ListIterator(this); 

  public void displayList() {

    Link current = first;

    while (current != null) {
      current =; 


class Link {
  public long dData; 

  public Link next; 

  public Link(long dd) {
    dData = dd;

  public void displayLink() {
    System.out.print(dData + " ");


Related examples in the same category

1.Listing the Elements of a Collection
2.De-mystify the Iterator interface, showing how to write a simple Iterator for an Array of Objects
3.Iterate over Set
4.Demonstrate iterators.
5.Use the for-each for loop to cycle through a collection.
6.Iterate a Collection and remove an item (Exception, wrong version)
7.Use an Iterator and remove the item with Iterator.remove()
8.An Iterator wrapper for an Enumeration.
9.EmptyIterator is an iterator which is empty.
10.Implements an java.util.Iterator over any array
11.Treat an Iterator as an Iterable
12.Iterator class for sparse values in an array.
13.Iterator class for values contained in an array range.
14.Array Iterator
15.Cyclic Iteration
16.Create singleton Iterator
17.Empty Iterator
18.An Iterator that wraps a number of Iterators
19.An Iterator to iterate over the elements of an array
20.Sorted Iterator
21.Iterator Union of Iterators
22.Iterator Utils
23.Linked Iterator
24.Prefetch Iterator
25.Protects an given iterator by preventing calls to remove().
26.An Iterator that returns the elements of a specified array, or other iterators etc.
27.An Iterator wrapper for an Object[], allow us to deal with all array like structures in a consistent manner.
28.An array iterator
29.Adapt iterator to iterable
30.Static utility methods, classes, and abstract classes for iteration.
31.Iterator Collection
32.Convert Iterable to List
33.A singleton null object Iterator implementation.