Iterating Through Linked Lists
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 .
View Replies
ADVERTISEMENT
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.
View Replies
View Related
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.
View Replies
View Related
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] ....
View Replies
View Related
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.*;
public class ListNode<T extends Comparable> {
ListNode<T> nextNode;
T data;
public ListNode(T item)
[Code] .....
View Replies
View Related
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]));
}
}
View Replies
View Related
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]....
SUMMARY: Whenever I set the head of a Linked List to a new node, it changes the head of all my linked lists to point to the same new node
View Replies
View Related
Oct 29, 2014
Basically, the program is to be able to read information from a file like this;
11111 63.5
22222 59.9
33333 82.4
44444 73.1
55555 77.3
66666 99.5
77777 68.7
88888 53.2
99999 66.8
where the first number is student number and the second is their grade. I need to read this information from a .txt file and dynamically create a new node containing that student's number and mark, and insert it in the correct position in the linked list (in descending order based on grade). So I get that each Node needs to contain two data types, an Int for Student # and a Double for their grade, and I'm pretty sure I've done it correctly with my StudentNode class which can be found in the source code linked above.
But what I don't get it using that class to create Nodes in my main class and then sort them based on their Double grade value WHILE they are being sorted. I just don't understand where to actually put the methods and such that does these things. Apparently I'm supposed to have three classes.
One named StudentNode which is just the node info, which I have done.
The second is called StudentList which is apparently supposed to contain the head of LinkedList and the methods I need? I'm not sure how it ties into StudentNode though.
The third and final is just the main class which I'll use to test it.
Then after all that I need to print out the median mark through a recursive method that isn't allowed to use any loops or call and functions/methods that use loops. The function should return the node in the list which contains the median mark. Secondly, in order to find the median, you need to know how many items in total are in the list. Your recursive function must calculate that number (also recursively); you may not keep track of this count elsewhere your program. Your recursive solution should only examine each node only once, and the depth of the recursion should be equal to the number of nodes in the list.
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.
View Replies
View Related
Oct 25, 2014
I'm not sure if my understanding of PriorityQueues is correct, so I'm trying to check if my reasoning is valid. I'm supposed to compare the Big-O for arrays and linked lists for the following instructions:
Insert 100 objects having the priorities 1, 2, 3, ... , 99, 100
Big-O for Array: __________
Big-O for Linked List: ___________
Insert 100 objects having the priorities 100, 99, 98, ... , 2, 1
Big-O for Array: __________
Big-O for Linked List(Assume no tail reference): ___________
If my understanding is correct, priority queues take in items randomly with no particular order, but they are removed according to the priority of each element. If what I've said is true, wouldn't that mean that inserting any number of objects would be O(1) for both linked lists and arrays? If the PriorityQueue has no particular order, then wouldnt each add() simply insert something to the next array index/linked list node?
View Replies
View Related
May 6, 2015
I am trying to implement product method below which returns the set representing the Cartesian product of the current set and a given set (the Cartesian product contains all ordered pairs (a, b) where a belongs to the current set, and b belongs to the given set). The product should be a ListSet <Tuple<E>> object where each ordered pair is a Tuple element. (I have a Tuple class which implements an ordered tuple)
What am I trying to do in the product method : Make 2 for loop and inside the for loop make an array of <E> then set the 2 elements of the tuple then again set tuple and add it to arrayList. how to set 2 elements of the tuple and set tuple ??
public class ListSet<E> implements Iterable<E>{
SinglyLinkedList<E> sl;
public ListSet(){
sl = new SinglyLinkedList<E>();
[code]....
View Replies
View Related
Nov 2, 2014
How to go through each link item in both lists, and directly link them into the new list in order without using insert()
class Link {
public long dData; // data item
public Link next; // next link in list
// -------------------------------------------------------------
public Link(long dd) // constructor
{ dData = dd; }
// -------------------------------------------------------------
public void displayLink() // display this link
{ System.out.print(dData + " "); }
} // end class Link
[Code] ......
View Replies
View Related
Mar 11, 2015
I am trying to generate table rows from LinkedHashmap sent from servlet. But whenever i execute i get empty or null map. I tried running the servlet alone to check whether the data is existing in linkedhashmap and it does. But only when i pass it to the jsp page i guess i am receiving an empty map.
Below is the code
Jsp Code:
<%@ page language="java"
contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
[code]....
View Replies
View Related
Aug 24, 2014
Today I installed jdk1.8.0_20 on my computer and typed a simple example code in MyEclipse 6.0 IDE, the code listed below:
import java.util.List;
public class Test5
{
public static void main(String[] args)
{
List<String> features = Arrays.asList("Lambdas", "Default Method", "Stream API", "Date and Time API");
features.forEach(n -> System.out.println(n));
}
}
the MyEclipse Editor shows some errors like "Arrays can not be resolved" and "n can not be resolved".
I did use jdk 8 in the build path, but it seems like the jdk 8 did not function properly.
View Replies
View Related
Jul 2, 2014
I have a a hashmap in request attribute which is available to jsp file where i have a dropdown. Hashmap kay= value of this dropdown. As and when I select CLT i want to perform some opertation depending on value associated with that key in hashmap.
View Replies
View Related
Apr 23, 2014
I currently have the code set up to iterate through objects and keep track of them but how do I do the same and draw the objects on the panel window? I'm confused on what to do and how to start it.
Here's the code I have so far, the 'Car' which I want to draw extends to another class which extends to GameObject. I currently have a 'draw()' method under the 'Car' class but nothing in the 'draw()' method yet. From what I understand i'm suppose to have a 'draw()' method under 'GameObjects' class also?
public class MapView extends JPanel implements IObserver, ActionListener{
JPanel myPanel;
private Timer timer = new Timer(5, this);
int x = 0;
int moveX = 2;
public MapView(){
super.setBorder(BorderFactory.createTitledBorder("Map:"));
[code]....
Mostly I don't understand how to go through the iterator again to paint the objects. Wouldn't I need to put another iterator under 'paintComponent()' or can it be done under 'update()' ?
how to get some shapes from the GameObjects onto my panel.
View Replies
View Related
Apr 18, 2015
my code is ignoring the checkbox option when Iterating in loop like this:
<tbody>
<c:forEach items="${users}" var="user">
<tr>
<td><input type="checkbox" name="deleteFromList" value="${user.id}"/><input type="submit" value="Delete" name="action" ></td>
</tr>
</c:forEach>
</tbody>
The output of value="${user.id}" is retrieved from a DB, it looks like this:
Id Nombre usuario Email Fecha de registro Acción
1 isaac2 @2 1986-01-01 *Delete(input) *Here there is check box
2 isaac3 @3 1988-01-01 *Delete(input) *Here there is check box
Then depending of which check box I selected then the row by the side should be selected by id and deleted.But what happens is that doesnt matter which check box I select, always the first row is deleted. I understand that at the first iteration of the loop it just take the first id, it doest attach the id I have choosen to the row it belongs to
View Replies
View Related
May 20, 2015
I have to create a method to find the current month with the input being a number of milliseconds using System.currentTimeMillis(). Now I was able to solve the problem with the following extremely cumbersome method:
public static int monthLeap(long ms) {
int result = 0;
int jan = 31, mar = 31, may = 31, jul = 31, aug = 31, oct = 31, dec = 31;
int apr = 30, jun = 30, sep = 30, nov = 30;
int feb = 28;
int febLeap = 29;
[Code] ....
I first go through a loop that goes through all the years and subtracting the number of days of a normal year or a leap year in milliseconds from the total milliseconds. At the end I should have a rest value of milliseconds that represents the amount of milliseconds that have passed already this year. Out of this number I then find the month we are currently in.
My problem is that the above method is way to large and I get a checkstyle warning: "NPath Complexity is 12,288 (max allowed is 80)".
I know that this can somehow be solved with a for loop iterating through the time and counting up months until there is no more month left. My problem though is the different lengths of the months. If each month was the same I could just subtract the amount of days in each month from the rest value.
(Since I already got it down to <= 12 months, I shouldnt bother with the extra days to find the month. Yet if I want to find the month when the date is the first or last day of the month it is important to be very precise) ....
View Replies
View Related
Apr 22, 2015
I have a list of 100,000 + names and I need to append to that list another 100,000 names. Each name must be unique. Currently I iterate through the entire list to be sure the name does not exist. As you can imagine this is very slow. I am new to Java and I am maintaining a 15+ year old product. Is there a better way to check for an existing name?
View Replies
View Related
Jul 5, 2014
Suppose i have given a List<Intervals> list; I am iterating over list and inserting each element from list into BST, if time require to insert into BST is logn then what is the total time require to insert all the elements into tree ?
logn or nlogn ?
View Replies
View Related
Aug 6, 2014
public void myFunc(MyNode n, ArrayList<MyNode> path) {
boolean hasChildren = false;
path.add(n);
int index = path.indexOf(n);
ArrayList<MyNode> statefulPath = new ArrayList<MyNode>();
[Code] ....
I have similar code that I stepped through in a debugger. After running the code I found that it built the desired tree, in this case a root node H with left child L and right child P. I want list of lists to contain all paths from root to leaf. I expected [H, L] and [H, P]. I discovered that statefulPath is not stateful; after a recursive stack frame pops, statefulPath still contains n! But that stack frame just popped! I expected to see statefulPath be [H] in the debugger and it was [H, L]! So I later have a list [H,L,P] which I don't want. How do I make the statefulPath list I want for my algorithm?
View Replies
View Related
Mar 25, 2015
List list1 = query1.list();
List list2 = query2.list();
for (Iterator itr = list1.iterator(); itr.hasNext();) {
Object[] row = (Object[]) itr.next();
}
View Replies
View Related
Jun 1, 2014
I have big problem with mergesort in Java. I can't figure out why it do not works. I need write it on lists using Comparable. Here is piece of code:
Java Code:
class MergeSort{
Comparator _comparator;
List lista = new ArrayList<>();
List list_temp = new ArrayList<>();
MergeSort(Comparator comparator){
[Code] ....
I have tried everything, still no results. It's return list with random placed numbers.
View Replies
View Related
Dec 6, 2014
What is going on here in the main class is a zoo that requires information to be read from and saved to a .txt file. I have made three arrayLists for each .txt file, I am getting errors for illegal start to an expression
import java.io.*;
import java.util.*;
public class ColumbusZoo
{
public static void addHelper(ArrayList<DomesticAnimal> a){
Scanner s = new Scanner(System.in);
System.out.println("What species");
[code].....
View Replies
View Related
Apr 1, 2014
I am working on a assignment that has to do with array lists, it mainly has to do with adding new elements, telling then where it is it located, if the memory block is empty , ect. so far i have been having problems with my indexOf method which should display the array cell number that a input element E is in, and if it is not in there it should display a -1.
public class MyArrayList<E>
{
private E[] data_store = (E[])new Object[2];
private int sizeofa = 0;
private void resize()// makes the array list bigger if need {
E[] bigspacemaker = (E[])new Object[data_store.length * 2];
for(int x = 0 ; x< sizeofa ; x++)
[Code] ....
Error message:
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 512
at MyArrayList.indexOf(MyArrayList.java:28)
at MyArrayListDemo1.main(MyArrayListDemo1.java:26)
View Replies
View Related
Feb 5, 2014
A Employee Class where i want to sort there lists one by there salary and one by there name individually as per the requirement ? How we do it?
View Replies
View Related
Mar 18, 2014
I am familiar with Java but new to JSP. I have a Java Servlet app where user actions are recorded in a SQL Server database amd I now need to quickly put together a JSP front end application to view user actions. I want two drop down boxes to filter the results that will be displayed in a list box. What I need is the first drop down list box to show unique user names that have logged in. I can interrogate the database with the following SQL;
"SELECT DISTINCT(USER_ID) FROM AUDIT_MESSAGE"
Then when a user is selected from the first drop down list box (perhaps some sort of on change event) a second drop down list box shows the logins times of the selected user. Again I can interrogate the database with the following SQL;
SELECT SESSION_ID, EventTIME FROM dbo.AUDIT_MESSAGE
WHERE OPERATION = 'loginResponse' AND RESULTS = 'OK'
AND USER_ID = 'firstdropdownlistselection'
Then finally when a login time is selected in the second drop down list box all events for the selected user while logged in with that login time are displayed in the list box.
View Replies
View Related
