Sorting A List Error?
Jun 12, 2014
I am reading a file and sorting a list, and I cannot figure out why I am getting an error on line 15 that contains the following code
Collections.sort(sortedContributorList, new Contributor());
This is the error I keep getting:
The method sort(List<T>, Comparator<? super T>) in the type Collections is not applicable for the arguments (LinkedList<Contributor>, Contributor)
import java.util.*;
import java.io.*;
public class myhashTable {
public static LinkedList<Contributor> sortedContributorList = new LinkedList<Contributor>();
public myhashTable(){
[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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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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Sep 13, 2014
package progProject5;
// Implementation of single linked list.
public class SingleLinkedList<E> {
private Node<E> head = null;
private int size = 0;
// Methods
[Code] ......
I am in learning process and I know its very basic question but I got stucked at addAfter() where I need to insert the node after the given node.
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Jan 24, 2015
I am using netbeans and have an error that reads "incompatible types: String cannot be converted to List<String>"
List<List<String>> fileDArr;
fileDArr = new ArrayList<>();
Scanner tempStringScanner;
try {
for (int i = 0; i < FileDirectory.length; i++) {
[code] .....
I don't understand why I am receiving the error. I thought that .next() returned a String?
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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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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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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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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?
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Dec 30, 2014
I receive a java.lang.NumberFormatException: For input string: ""DepDelayMinutes"" error when trying to filter a list and then assign the results to a new list.
I have edited the code so it is an int that throws the exception so it isn't the presence of a string that is causing the error - java.lang.NumberFormatException: For input string: ""0914"" .
I believe the issue is because of the two sets of double quotes but I do not understand how they came about. The original dataset does not have any quotes whatsoever.
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.function.Predicate;
import java.util.stream.Collectors;
public class FilterObjects extends Thread{
[Code]...
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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 ?
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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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Feb 14, 2015
I saved the content of an ArrayList<SomeClass> to a file
I write each serialised object to the file by adding to each an id that is created with list.indexOf(object) (and saved before each object)
So I can repopulated the list with SomeClass objects in the same order as they were and once I reload the file, I do list.add(id,object)...
Well my list is populated upside down, I mean the first object is the last and the other way around, If i remove the id when I do the add(object)...
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Mar 26, 2014
I am trying to sort an ArrayList of objects with the comparator as I want to sort based on a certain value for each object. I understand I would need to override compareTo() in the objects class, is there any way I can get around also needing to override for all subclasses of the object?
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Oct 16, 2014
So we have to ask the user to put in a string of letters, and bring those letters in as cars to where there is a storage area and an assembly area, and we have to sort them from there into the assembly area with the smallest (A) at the head. I think I set up my code pretty well, but when I run it, no matter what I put in it returns CBAo. Say I input KATE, it should return TKEA but instead CBAo or if I input JANICE it should return NJIECA but it just returns EDCBAo. Here's my code:
import java.util.Scanner;
import java.util.Stack;
public class carStacksDessart
{
public static void main(String[] args) {
Stack<Integer> storage = new Stack();
[Code] ....
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Nov 30, 2014
I'm trying to create a method that takes a map and sorts it alphabetically. I think I have the logic correct but I'm getting errors when I run it:
private static void sortMapAlphabetically(
Map<String, String> termsAndDefinitions) {
Map<String, String> tempMap = new Map2<String, String>();
[Code].....
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Nov 26, 2014
I have to sort out my ArrayList but cannot make it work. Here is
Java Code:
Collections.sort(this.users);
User poor = this.users.get(0);
User ritch = this.users.get((this.users.size()-1));
System.out.println("Poorest user has" + poor.getUsername() + poor.getBalance() );
System.out.println("Ritches user has " + ritch.getUsername() + poor.getBalance() + "
"); mh_sh_highlight_all('java');
The Collections.sort(this.users); does not work.
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Jun 21, 2006
i am doing a code using JSTL to fire a query. everything come fine except the resule is not sorted as desired. i am putting the code below--
String sort_order=(String)request.getAttribute("sort_order");
request.setAttribute("sort_order",sort_order);
<sql:query var="viewQueryj" sql= "select USER_ID, PERMISSION_ID, USER_NAME from administrator order by ?">
<sql:param value="${sort_order}"/>
</sql:query>
now the resule is always sorted by USER_ID. if i want to sort it using USER_NAME i pass parameter from controller to this page in sort_oredr variable which comes fine but the result doesn't sort by name, only by id. if i hardcode USER_NAME in query then the result is as desired.
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Sep 16, 2014
I need to sort a 2D array to look like this : [URL] ....
Here is the code that I have.
File 1:
import java.text.DecimalFormat;
public class Assignment1 {
public static void main(String[] args) {
String[][] rainArray
= {
{"January", "3.03"},
[Code] ....
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Nov 18, 2014
The following code is supposed to generate random integers and sort array1 and array2 using two different sorting methods. array1 is to be sorted with a "selection sort" method and array2 is to be sorted with the built-in Arrays.sort() method. However, array1 is the one that has a problem. It does not appear to output any values at all for array size of 4000 or more, such as array1[10000]. The assignment is to generate random integers, sort and benchmark the speeds at which array1 and array2 can generate and sort ints at array1[1000] array2[1000] array1[10000] array2[10000] array1[100000] array2[100000]
/**
*
* The following is a sorting and benchmarking program to sort
* array1 and array2 with 1,000 , 10,000 and 100,000 array sizes.
* array1 uses selection sort from section 7.4 of the book
* and array2 uses the built in Arrays.sort() method.
[code]....
I cannot post the output because the amount of data seems to have crashed the two previous posts I made on this topic due to the size of the problem.
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Jan 2, 2015
I have a code that is meant to read a file and organize all the names from least to greatest salaries. It also allows the user to enter a name to find from the file, and the program finds the name and displays it. I have two errors, and I will show the error in my code
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Feb 23, 2014
I'm very new to Java and ran into a problem. My results are not in order and I'm not sure what I'm doing wrong.
My results come out like this instead of being in order from lowest to highest: "77 99 44 55 22 88 11 0 66 33"
Here's what I have:
class ArrayIns {
private long[] a; // ref to array a
private int nElems; // number of data items
//--------------------------------------------------------------
public ArrayIns(int max) // constructor
{
a = new long[max]; // create the array
nElems = 0; // no items yet
[Code] .....
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Apr 22, 2015
I'm getting this error:
The operator < is undefined for the argument type(s) java.util.ArrayList<FacebookUser>, java.util.ArrayList<FacebookUser>
For this:
class FriendsComparator implements Comparator<FacebookUser>
{
@Override
public int compare(FacebookUser o1, FacebookUser o2)
{
int returnValue = 0;
if (o1.friends < o2.friends)
returnValue = -1;
[Code] ....
Same as for the second if condition. How can I fix this exactly? What I'm doing is trying to sort Facebook users by the most to least amount of friends.
Here's the Driver:
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.util.Scanner;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
[Code] .....
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Sep 17, 2014
I'm trying to sort 10 inputted numbers (double precision) using the Array.sort() method. I can get the 10 numbers inputted, but the output is ten 0.0s; now (and this how I know I am learning some things) I'm fairly certain that the variable number is not storing the numbers inputted by the user otherwise I wild be seeing the program work correctly.
So my question is why isn't number storing the inputs?
import javax.swing.JOptionPane;
import java.util.Arrays;
public class KrisFrench3 {
public static void main(String[] args) {
double[] number = new double[10];
for(int i = 1; i <= i; i++) {
[Code] .....
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Jul 1, 2014
Write a method called isSorted that accepts an array of real numbers as a parameter and returns true if the list is in sorted (nondecreasing) order and false otherwise. For example, if arrays named list1 and list2 store {16.1, 12.3,22.2, 14.4} and {1.5, 4.3, 7.0, 19.5, 25.1, 46.2} respectively, the calls is Sorted(list1) and isSorted(list2)should return false and true respectively. Assume the array has at least one element. A one-element array is considered
to be sorted. public class thirfd {
public static void main(String[] args) {
double[] arr1 = {16.1, 12.3,22.2, 14.4};
double[] arr2 = {1.5, 0.3, 7.0, 19.5, 25.1, 46.2};
isSorted(arr2);
System.out.println(isSorted(arr2));
[code]...
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Jan 9, 2015
I'm trying to troubleshoot on some existing code that is causing some confusion for me. The code is a snippet from a navigation display that displays Sections of an image. Each section is actually a total of 75 pages and I have an image that is being returned with over 3000 pages. Depending on other images being returned, I won't always know how many total pages or total sections will be returned.
The issue is that when the section numbers are being returned on the screen (strSectionURL = "Section "+ strSectionNumber; ) they are not in numeric order on the display. For example, instead of being 1 - 10 as they are returned (the XML response shows me the section numbers are being retrieved in numerical order), they come back "Section 4, Section 1, Section 10, etc when the URLs are displayed.
Why do they not show in numerical order on the navigation display?
Copy of the class:
NavDisplay.txt
String strInvocationId = null;
String strStatusString = ImageDisplayHelperBean.IMG_STAT_ERROR;
StringBuffer sbfStatus = new StringBuffer();
String strStatus = null;
String strCSSClass = "IMAGE_ERROR";
String strSectionURL = null;
[Code] ....
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