Double Circular Linked List - Implementing Iterator
Oct 14, 2014
My homework is a Double Circular Link list and when i write implements Iterator it gives me a an error when I compile it the same for my subset method...
ERRORS :DoublyCircularList.java:55: error: DoublyCircularList.iterator is not abstract and does not override abstract method remove() in Iterator public class iterator implements Iterator<T>
^
Note: DoublyCircularList.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
1 error
import java.util.Iterator;
public class DoublyCircularList<T extends Comparable<T>> extends LinkedList<T>implements Iterable<T>
{
Node<T> first;
int size;
public DoublyCircularList(){
first = null;
size = 0;
[code]....
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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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Apr 6, 2014
I am creating a josephus java program with a circular linked list.This is what the methods are suppose to do
a. size(): Returns the number of items in the list.
b. isEmpty(): Returns true if the list is empty and false otherwise
c. advance(): Moves the cursor from the current position to the next item. If the cursor is at the end (tail) of this list, calling advance() should make the cursor refer to the first element in the list. If the list is empty, this operation should have no effect.
d. getCurrent(): Return the String value in the node referenced by the cursor unless the CircularLL is empty in which case write an error message to System.err.
e. add(String data): Adds a new item to the list by creating a newNode and linking it to the end of the circular linked list. The last node should point to the new node and then you should make lastNodeInserted point to new node as well.) Please note that a circular linked list is always circular. The last node should point to the beginning node. When there is only one node in a CircularLL, its next should point to itself. This method updates currNode when the first node is added, and always updates lastNodeInserted and numNodes. Take care when adding the first node this is a special case and should be handled differently.
f. remove(): If the list is empty, write an error message to System.err indicating that an attempt was made to remove from an empty queue and return null. Assuming the list is't empty, this method removes the node currently referenced by the cursor, reassigns the cursor to point to the next node in the list, and returns the String value stored in that node. To keep the list linked, you'll need to locate the previous node to the one youre removing and connect its next to the node which follows the one youre removing. Create a local Node variable (prev) to find it. Consider and handle the special case when there is only one node and youre removing it. And make sure to update lastNodeInserted whenever you remove the node that it is pointing to.
g. toString(): This should return a String representation of the circular linked list, with the first value displayed being the data of the first node added (not the data in the last node).
public class CircularLL {
private class Node {
String data;
Node next;
public Node(String data) {
this.data = data;
this.next = null;
[code].....
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May 3, 2014
I have a problem with a linked list iterator, my problem is implementing the iterator.remove method given the following code:
package mapsql.util;
import java.util.Iterator;
public class LinkedList<T> implements List<T> {
private class Node implements Position<T> {
T element;
Node next, prev;
public Node(T element) {
this.element = element;
[Code] ....
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Oct 27, 2014
So I'm trying to build a queue, first in first out, (so add to the head remove from the end) using a linked list for use in another program, I'm having a problem dequeueing where the program seems to run indefinitely without giving an answer, so my suspicion is its caught in a while loop but how and why I can't figure out.
public class CircularQueuelist {
private Node head = null;
private int size = 0;
private class Node
{
int data;
Node next;
[Code] ....
My logic seems sound, I basically look for when the second node over from the current one I'm on is a reference to the head, and then skip the one in front of it using setting currents. next link to current.next = head, severing the link to the last node.
This is what my driver looks like, I enqueue items 1-10 and then use the iterator to make sure it worked out fine and check size, its when I dequeue that I run into a problem, the program runs indefinitely.
public class Queuetest {
public static void main(String[]args)
{
CircularQueuelist test = new CircularQueuelist();
for (int count = 0; count < 10; count ++)
[Code] ....
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Apr 17, 2015
I am trying to implement a singly linked list. My singly linked list, where I implemented a class named linkedlist, that I defined (this implementation of linkedlist is not the java class linkedlist, it is my own version of linkedlist):
Java Code:
public class SinglyLinkedList<E> implements LinkedList<E> {
public class Node<E> {
public Node<E> next;
public E element;
public Node(E element) {
this.element = element;
}
public Node (E element, Node<E> next) {
[code]...
But when I go to my main method to add into my SinglyLinkedList, it doesn't add anything.
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Sep 11, 2014
I've been stuck for the last couple hours trying to understand why the "printInReverse" method is getting into an infinite loop. I was supposed to make a double linked list that you can insert numbers and it orders both ascending and descending; in this case, descending is the "printInReverse" method, which takes the already ordered lists and prints it reversed, like if it was descending, and that's where the problem lives. Here follows the whole code:
import java.util.Scanner;
public class MyList {
private Scanner userInput;
private Integer selectedOption;
private MyListElement firstElement = null;
private boolean exitRequested = false;
[Code] .....
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Sep 12, 2014
I have the following double linked list and I'm supposed to order it descending (reverse) using the printInReverse() method; since the list orders itself ascending when the numbers are added, how could I order it descending in this method? Here's the code without implementing descending/reversing methods:
package test;
import java.util.Scanner;
public class MyList {
private Scanner userInput;
private Integer selectedOption;
private MyListElement firstElement = null;
private boolean exitRequested = false;
[Code] ....
I tried to declare a previousElement variable but I didn't figure out how I'd do that.
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May 25, 2014
I am currently making a double linked list class in my compsci class. i was absent for a few days and i need to make an add method for the class. when i go to compile test code i made i get a null pointer error on line 36. This is the node class i wrote and the double linked list class i wrote.
node class
public class Node{
// Two references and Data
Node prev;
Node next;
String data;
public Node(){
prev = null;
next = null;
[Code] ....
This is the class i need working with ( in the doublelinkedlist class)
public void add(Node n){
if(isEmpty()){
first = n;
return;
}
Node temp = first;
while(temp != null){
temp = temp.getNext();
}
temp.setNext(n);
temp.setPrev(temp);
}
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Sep 12, 2014
I wrote displayAscending() and displayDescending() methods to this double linked list and it is not working at all. Logically it seems fine to me. I positioned the head in the beginning in the ascending method; created a variable named data1 as an auxiliar variable so it can store the values that are going to be moved; and moved the values. Same thing for the descending method but instead of the head I put the tail and move left the list, instead of right.
import java.util.*;
class node {
int data;
node left;
node right;
node(int d, node l, node r) {
data = d;
[Code]...
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Nov 5, 2014
List<Integer> list = new ArrayList<Integer>();
for (int i = 0; i < 5; i++) {
list.add(i * 3);
}
ListIterator<Integer> listItr = list.listIterator();
System.out.println("Traversing in a forward direction");
[Code] ....
Output:--
Traversing in a forward direction
0 3 6 9 12
Traversing in a backward direction
12 9 6 3 0 425
Why 425 is not showing when we are traversing in a forward direction.
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Feb 14, 2014
I have some class called sorted to sort the linked list through the nodes of the list. and other class to test this ability, i made object of the sort class called "list1" and insert the values to the linked list.
If i make other object called "list2" and want to merge those two lists by using method merge in sort class. And wrote code of
list1.merge(list2);
How can the merge method in sort class know the values of list1 that called it as this object is created in other class.
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Oct 5, 2013
So we have an assignment regarding a linked list implementation of a given list interface.
In my list interface, the method contains(T anEntry) is defined.
In the LList implementation, contains is already implemented as part of getting the core methods in.
Now I am being tasked with the following:
Provide a second implementation of the method contains2(T anEntry) that calls a private recursive method
Private boolean contains (T anEntry, Node startNode) that returns whether the list that starts at startNode contains the entry anEntry.
I've written the private recursive method already. That's not an issue (at least not right now).
But what I don't understand is how startNode is supposed to be populated when this private contains method is called from the public contains2 method? contains2 only takes one parameter: anEntry. the private method takes two parameters: anEntry and startNode. How am i supposed to provide startNode when I am calling contains2?
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Oct 6, 2014
I have this ListInterface class that has operations for my linked list and a LList class. The Llist and ListInterface classes are perfect. My job is to create a driver, or a demo class that showcases these operations. That being said, heres the driver so far:
import java.util.*;
public abstract class DriverWilson implements ListInterface
{
public static void main(String[] args)
{
LList a = new LList();
[code]....
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Mar 21, 2014
What I'm supposed to do is make a method to insert a set of Tiles to the list,i.e.,a detour(make sure that the inserted detouris compatible with thecurrent path so that the resultingpathdoesnot have any gaps). But I'm confused on how to go about doing it. I was thinking of maybe just adding 1 to the current Node.
import java.io.File;
import java.io.FileNotFoundException;
import java.util.List;
import java.util.Scanner;
public class Path {
static Tile startTile;
[code].....
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Jan 30, 2014
I'm trying to implement an Office class that contains an inner class: WorkerNode. The WorkerNode class has a name attribute (String) and WorkerNode attributes for boss, peer and subordinate. The attributes of Office are manager and current which are WorkerNode references. The manager refers to the entry point of the structure and current is the current node in the structure. For simplicity, i'm going to try to limit it to 3 levels and assume that the names are unique. I've put together a Office class that containing main and provided the code I've worked on so far.
public class Office {
public static void main(String[] args) {
String name=Input.getString("input the manager's name: ");
Office office=new Office(name);
int option;
[code]....
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Apr 20, 2014
I have made a node class and im trying to implement a sorting method. I must use a selection sort but with specific instructions: "Your method should not need to use the new operator since it is just moving nodes from one list to another( not creating new nodes)
this is my current implementation ..but i am instantiating new object..
public class NodeInt
{
private int data;
private NodeInt next = null;
public NodeInt(){}
//precondition:
//postcondition:
public NodeInt(int data, NodeInt next)
{
this.data = data;
this.next = next;
[code]....
edit: this is the part that worked but i had it commented out so i have the previous and current declared above but didnt copy.
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Apr 30, 2014
Ok here I have a code that generates 1 million random values then converts them to a string then hashcode. I then insert into a linked list and then I want to run through each hash and find it in the linked list timing each run then averaging out the time at the end.
It works great for smaller amounts of numbers it is searching for (fine under 50 thousand searches for the for loop starting at line 24 LinkedListTest.java) but when I try to do the full million searches it gives me "a Exception in thread "main" java.lang.StackOverflowError" at line 158 in List.java. Maybe im getting tired but I cannot figure out why.
// class to represent one node in a list
class ListNode< T >
{
// package access members; List can access these directly
T data; // data for this node
ListNode< T > nextNode; // reference to the next node in the list
[code]....
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May 1, 2014
public void add(int d){
listNode l = new listNode (d, null);
l.next = first;
first= l;
}
public list Sum2List (list l1, list l2){
//variables
int sum;
[Code] .....
But I have a problem in my first listNode where it ll be pointing to null, thus in the sum2List method the program checks the while condition into false and doesn't go through the loop.
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Jan 31, 2015
if one address point on another address. so set and get methods will be less efficient then an array, but add or remove will be more efficient by a linked list ? a linked list also inherit from queue so if i add an elemnt via "addFirst" function . where its adding the element ? to the right most or left most ?
if i have for example :
here [ ] --> [ ] --> [ ] --> [ ] -->[ ] or here
linked list its FIFO so the head will be the right most ?
Edit : its confused me a little bit but i understood now .so it will be at the left most. its actually ordered . not like the stack which is LIFO.
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Oct 30, 2014
I searched a lot but can't seem to understand the sorting of a SLLNode... I noticed a method called Bubble Sort, I understand how it works, but can't think of a way to implement it to my code..
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Dec 30, 2014
Is there a particular implementation of a linked list you are referring to in your question?
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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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Oct 17, 2014
i tried everything but its giving me errors. i tried the for loop but its giving me something else.
this is what i have to do Write a recursive method that prints out the data elements of a linked list in reverse order.
Your method should take in as a parameter the head reference to a linked list. Then, write a recursive method that returns a count of the number of elements greater than a given threshold. You may assume that the data elements in the linked lists are ints. The parameters of your method are a reference to the linked list and a int value representing the threshold.
public class recursion3
{
public static void main(String [] args) {
char a [] = {'A', 'B','C','D','E'};
System.out.println(a);
}
public static String reverseString(String s) {
if (s.length() <= 1) {
[code]....
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Feb 17, 2015
I'm trying to print the contents of my linked list. I'm using nodes and within those nodes it hold String data. So i want to print out the data within the nodes. Whenever i do
System.out.println(node1.data),
it prints perfectly. But i'm trying to use a method where it would loop through the list and print out the data for every node in it. when i run my print method i get results such as
Node@15db9742
Node@6d06d69c
Node@7852e922.
Here is my print method i created
Java Code:
public void print(){
Node<E> current = head;
while (current.next != null){
System.out.println(current.data);
current = current.next;
}
} mh_sh_highlight_all('java');
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Apr 12, 2014
I am creating a recursive method to reverse a linked list in java. It works the first time when I call it, but I want it to work where I call it a second time and it reverses it to the original state. How can I get that to work with this implementation?
public void reverseList() {
System.out.printf("%-16s%-3s%n", "Name", "Score");
System.out.println("--------------- -----");
reverseList(first);
} public void reverseList(Node aNode) {
if (aNode != null) {
reverseList(aNode.next);
System.out.printf("%-15s%6s%n" , aNode.name , aNode.score);
}
}
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