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Thread: Linked list help simple little problem i need help with

  1. #1
    Junior Member
    Join Date
    Feb 2013
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    Default Linked list help simple little problem i need help with

    okay so heres my code

    import java.util.Iterator;
    import java.util.NoSuchElementException;

    public class LinkedList<Item> implements Iterable<Item> {

    private Node head;
    private Node last;
    private int size; //number of Nodes

    /*
    * head refers to the first node; head.previous is always null. last refers
    * to the last node; last.next is always null.
    */
    private class Node {

    private Item item = null;
    private Node next = null;
    }

    public LinkedList() {
    head = null;
    last = null;
    size = 0;
    }

    //Add to the end of the list
    public boolean add(Item item) {

    Node n = new Node(); //create a new Node object
    n.item = item; // store the data in this object
    n.next = null; // this node will be placed at the end of the linked list


    if (last == null) { //Adding to an empty LinkedList
    head = last = n;
    } else { //Adding to the end of a LinkedList with at least one element
    last.next = n; //the current last node points to our new node
    last = n; //last now points to the node we added
    }
    size++; //increase the size of the list
    return true;
    }

    public int size() {
    return size;
    }


    public boolean remove(Item item) {
    boolean found = false;

    if (head != null) { //if head = null, then the list is empty - return false

    if (head.item.equals(item)) {// 1st Node contains the item
    head = head.next; //remove the 1st Node
    size--; //revise the size of the list
    if (size == 0) //Did we remove the only item in the list?
    {
    last = null; // then set last to null
    }
    found = true; //we found the item in the LinkedList
    } else {

    Node current = head.next;
    Node previous = head;
    while (current != null && !found) { // current == null means we're at the end of the list
    if (current.item.equals(item)) { // we found a match
    previous.next = current.next; //remove the current node
    size--;
    found = true;
    if (current == last) // we're removing the last item
    {
    last = previous; //set last to previous
    }
    } else { //we didn't find the item, so go to the next Node in the LinkedList
    previous = current;
    current = current.next;
    }
    }//end while
    } //end else
    }

    return found;
    }

    public Iterator<Item> iterator() {

    return new LinkedListIterator();
    }

    private class LinkedListIterator implements Iterator<Item> {

    private Node current = head;

    public boolean hasNext() {

    return current != null;
    }

    public Item next() {
    if (!hasNext()) {
    throw new NoSuchElementException();
    }
    Item item = current.item; //get current key data
    current = current.next;
    return item;
    }


    public void remove() {


    }
    }
    //hw part

    NEED HELP BELOW HERE!

    public boolean removeLast() {
    boolean found = false;

    if (size!=0){
    Node current = head.next;
    Node previous = head;
    while (current != null && !found) { // current == null means we're at the end of the list
    previous.next= current.next;
    size--;
    found = true;
    if (current == last) // we're removing the last item
    {
    last = previous; //set last to previous
    }
    }
    previous = current;
    current = current.next;
    }
    return found;

    }



    public static void main(String[] args) {
    LinkedList<String> ll = new LinkedList<String>();


    ll.add("a");
    ll.add("b");
    ll.add("c");
    ll.add("d");
    ll.add("e");
    ll.add("f");
    ll.add("g");
    ll.add("h");
    ll.add("i");
    ll.add("j");
    ll.add("k");
    ll.add("l");
    System.out.println();
    System.out.println("size = " + ll.size());

    for (String e : ll) {
    System.out.println(e);
    }
    System.out.println();

    if (ll.removeLast()) {
    for (String e : ll) {
    System.out.println(e);
    }
    }
    System.out.println();

    if (ll.removeLast()) {
    for (String e : ll) {
    System.out.println(e);
    }
    }
    System.out.println();

    if (ll.removeLast()) {
    for (String e : ll) {
    System.out.println(e);
    }
    }


    }
    }





    and heres the out put i get

    run:

    size = 12
    a
    b
    c
    d
    e
    f
    g
    h
    i
    j
    k
    l

    a
    c
    d
    e
    f
    g
    h
    i
    j
    k
    l

    a
    d
    e
    f
    g
    h
    i
    j
    k
    l

    a
    e
    f
    g
    h
    i
    j
    k
    l




    My problem is how do i get the code to remove it backwords starting with L then J then j and so forth please help thank you !

  2. The Following User Says Thank You to perezbrandon92 For This Useful Post:

    thomas10 (June 7th, 2013)


  3. #2
    Super Moderator pbrockway2's Avatar
    Join Date
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    Default Re: Linked list help simple little problem i need help with

    double post. closing

  4. The Following User Says Thank You to pbrockway2 For This Useful Post:

    thomas10 (June 7th, 2013)

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