Doubly Linked Lists And Using Java Generics

Oct 25, 2014

I'm working with Doubly Linked Lists and using Java Generics..

My nodes looks like this:
class DNode<E> {
DNode<E> previous;
DNode<E> next;
E element;

//and all methods inside
}

My list of Nodes looks like this:
class DLL<E>{
private DNode<E> head;
private DNode<E> tail;
private int size;

[code]....

As you can see, as arguments they get "E o"...I need to write a program, which from the main function asks the users how long is the list, and after they type it's length, I ask them to start typing the elements (integers)...and this is how my main method is written, but I can't seem to make it work, specialy when I call the "insLast" method,I guess it's because the arguments i'm giving to the function...how to read the elements and write them into the list?

public static void main(String[] args) throws IOException {
DLL<Integer> lista=new DLL<Integer>();
BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
String s = stdin.readLine();
int N = Integer.parseInt(s);
s = stdin.readLine();
String[] pomniza = s.split(" ");
for (int i = 0; i < N; i++) {
lista.instLast(Integer.parseInt(pomniza[i]));
}

}

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Linked Lists In Java

Nov 27, 2014

I currently don't understand how the node's work.

private static class Node<AnyType>
{
private AnyType data;
private Node<AnyType> next;
public Node(AnyType data, Node<AnyType> next)
{
this.data = data;
this.next = next;
}
}

Why do I make private Node<AnyType> next;And why do I have an inner class of Node for a linked list?I had the same topic in C, but there it was somehow easier than in java. Because there you have pointers.

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Dec 11, 2014

I'm having some trouble with figuring out how to move along a doubly linked list for an assignment. The program is supposed to be a simple board game simulation. Here is what I have so far:

Space.java:

public class Space
{
private String name;
public Space next;
public Space previous;
public Space(String name)
{
this.name = name;

[Code]...

I seem to have been able to get all the other methods working properly, but I am pretty stuck on how to do the movePlayer. Specifically because it is passing an integer, but my objects are of type Space and Boardgame.

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Feb 12, 2015

For the program I have to create, I need to be able to work with the elements of a circular doubly linked list to do the following:

Find an element in the list (specified as an argument)
Insert an element after a specified element (specified as an argument)
Delete an element (specified as an argument)
Display the elements in the list

I can insert elements and display the elements, but I can't figure out how to search for an element, insert an element after a specified element, or delete an element.

What I am having trouble with is passing the elements in the list as arguments for searching, deleting, inserting after an element.

public class doublyLinkedList {
private Node pointer;
private Node dLL;
private int count;

[Code] .....

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Oct 26, 2014

How can I insert a new item at the middle of a BookList . I have also got a Book class represting Book objects and a inner class BookNode referencing them.

public void add(Book newBook)
{ BookNode newNode = new BookNode(newBook);
if (firstNode == null){
// no nodes in the list so add newNode at start
firstNode = newNode;
tempNode = newNode ; }

[Code] ....

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Apr 11, 2014

Im not sure why the nodes are not being deleted. Is a part of my logic wrong?

public void delete(String s) {
Node temp = find(s);
if (temp==null) {
return;
}
Node prevTemp = temp.prev;
Node nextTemp = temp.next;

[Code] .....

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Oct 30, 2014

I have a couple more (2or3) and I believe I'll be ready to go 8-)This one is about an Army and a list of warriors... for example 1,2,3,4,5,6,7,9,10 .... and the user inputs points for two sequences, for example 1, 5 and 6,10 .... That means I have to take the array from the 1st element, up to the 5th one, and swap it with the elements from 6to10....

The nest list should be:

6 7 8 9 10 1 2 3 4 5

Things to keep in mind: The list will always have at least two warriors. The intervals will never interfere, and will at least contain ONE warrior..

It says: be careful when the intervals are next to each other, and when be careful when an interval starts with the first warrior, or finishes with the last warrior.

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Doubly Linked List Check Palindrome

Oct 29, 2014

I cant figure out something in my code. I have to check whether given doubly linked list is palindrome or not. If it is palindrome it should print 1 , if not -1. My code has no errors but it always prints -1. I tried debugging but first comparisongives always false and function cant reach to else statement.

Are there any logical errors or i cant do right way of comparison?

import java.util.Scanner;
class DLLNode<E> {
protected E element;
protected DLLNode<E> pred, succ;
public DLLNode(E elem, DLLNode<E> pred, DLLNode<E> succ) {
this.element = elem;
this.pred = pred;
this.succ = succ;

[Code] ....

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Jul 15, 2014

I am trying to create doubly linked list that can hold huge numbers (i.e. 123456789) and add them together. I have seen some examples on how to do this for linked list, but none really for doubly linked list.

Here is my test driver:

public class HugeNumberDriver
{
/**
* Main method with some test code
*/
public static void main(String[] args)
{
// Create a HugeNumber that is 123456789
HugeNumber h1 = new HugeNumber();
for (int i=9; i>=1; i--)

[Code] ....

Output:

h1 is 987654321
h2 is 88888888885555555555
Exception in thread "main" java.lang.NullPointerException
at HugeNumber.<init>(HugeNumber.java:52)
at HugeNumberDriver.main(HugeNumberDriver.java:29)

As you can see the numbers are displayed incorrectly and the rest of the program does not run. I have a feeling that it has to do with my deep copy constructor or my addDigit() method

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Nov 15, 2014

I have a doubly linked list and i want to show the data in a table using java gui.

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Jun 5, 2012

Im running into some problems with the Java compiler. This is my code:

public class DoublyLinkedList<T> implements SimpleList<T> {
protected Node dummy;
protected int n;
public DoublyLinkedList(){

dummy = new Node();
dummy.next = dummy;
dummy.pre = dummy;

n = 0;

[Code] ....

I want to use a dummy node in my implementation of the Doubly Linked List, so it will be easier to code all the methods I need to write. I keep on getting a problem with line 14 and 15:

dummy.next = dummy;

dummy.pre = dummy;

// cannot find symbol variable next (compiler error)

// cannot find symbol variable pre

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Apr 27, 2014

Write a Java function Sum2List that takes two lists L1 and L2 of the same size and returns list L that contains the sum of data inside the corresponding nodes of lists L1 and L2.

ex: L1 = {1,2,3}
L2 = {4,5,6}
L = {5,7,9}

I do not know how to iterate through two different lists >>

public LinkedList Sum2List(LinkedList l1, LinkedList l2){
LinkedList l3 = new LinkedList();
ListNode Current1 = L1.getFront();
ListNode Current2 = L2.getFront();
while(Current1 != null){
l3.Add(Current1.getItem() + Current2.getItem());

[Code] .....

This my attempt to write the code , but the dr. side that we have not to use the build in methods ( getNext()...etc)
in the function .

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Mar 10, 2014

I have an XML sheet and my project is top retrieve the required elements from XML sheet. So my format of XML was like follows:

<Class>
<Employees>
<EMPLOYEE>
<ENum> Abc123</ENum>
<Ename> John<?Ename>
<EType>Mathematics</EType>

[Code] ....

I have used unmarshalling concept to retrieve the data elements... I have to check whether the elements satisfy few regulations when compared with data in Database. So, i thought of grouping the employees depending on EType. I have created a Map with linkedlist of employees. Say Map<String, LinkedList<Employe>>EmpMap=new Map<String, LinkedList<Employe>>();

I have already created a class named Employee which has all the setter and getter methods for employee.

Here am going to take Etype(Employee type) as key and linkedlist(list of employees of certain type) as value. How to iterate these linked lists and place them in my Map.

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Jul 19, 2014

Why is this method throwing a null pointer exception when I call it from main?

I'm trying to submit an integer to indicate the number of nodes in a linked list to delete and then delete them headfirst.

public boolean delete(int x){
if (x > count || head == null){
return false;
}else{ while (x>0){
head = head.getPrevious();

[Code] ....

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Feb 13, 2014

I have the following code that supposed to perfrom sorting on the linked list using method sort in order usind node concept of Linked List but seems to give inlogic results. the following code tests only the values lower than the first value but i can't manage to sort the data higher than the first entered value;

/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/

import java.util.*;
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ListNode<T> nextNode;
T data;
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[Code] .....

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Apr 16, 2014

I am creating a chained hash table that uses my own LinkedListclass to handle collisons. Here is where my issue is occuring: I start with an array of LinkedLists, my "hash table", intially set to null. When i wish to add a word, if the desired location is null, I create a new LinkedList, place it in that array index. I then create a new LinkedListNode and set the head of the new LinkedList to the new node.

My issue is occuring here: Whenever I set the head of my new LinkedList to my new LinkedListNode all of my previously created linkedlists also have their head changed to the new node.

My debugger shows that I am truly creating new linkedlists every time. I was afraid each array index was just pointing to a single array, but that is evidently not the issue. Below is all the relevant code

public class SetOfStrings {
private int arraySize;
private LinkedList[] mainArray;
private int totalCount;
//other methods here
public boolean add(String toAdd) {
int hashToAdd = hash(toAdd);

[code]....

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44444 73.1
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66666 99.5
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The third and final is just the main class which I'll use to test it.

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Here's my current in-progress code.

import java.io.FileNotFoundException;
import java.util.Scanner;
class StudentNode {
private int studentNum;
private double grade;
private StudentNode next;

[Code] .....

I'm pretty sure the StudentNode class is fine, it's the StudentList class that I'm not sure about. I'm not sure how to add nodes since there isn't a getNext() method in the StudentList class.

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public class ListSet<E> implements Iterable<E>{
SinglyLinkedList<E> sl;
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[code]....

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class Link {
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public Link next; // next link in list
// -------------------------------------------------------------
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// -------------------------------------------------------------
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[Code] ......

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Jun 5, 2015

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First, it specifies that E is a subtype of Comparable.

Second, it specifies that the elements to be compared are of the E type as well.

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Also, If the second list is different it has me enter more values that list one.

public static void main(String[] args) {
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[code]...

My output looks like this:

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2
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3
2

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