Sorting Out ArrayList
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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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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Oct 13, 2014
we have an Arraylist<Tweet>, and this class is defined as followe: public class Tweet implements Comparable<Tweet>, Serializable. now if we implement the method comparteTo, then will it be sorted automatically? I want to sort this array by any insert.
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Feb 11, 2014
I have a case in which I want to sort two types of ArrayLists (using quicksort) and the method originally coded only accepts a String ArrayList. The problem is that now I want to sort an ArrayList of type int but couldn't . . . so I decided to overload the method. Since it looks very ugly to copy and paste the same chunk of code only to change the method signature I wondered if there is a better way to make this method more dynamic and be able to take in different types of ArrayLists.
My code:
private ArrayList<String> sort(ArrayList<String> ar, int lo, int hi){
if (lo < hi){
int splitPoint = partition(ar, lo, hi);
sort(ar, lo, splitPoint);
sort(ar, splitPoint +1, hi);
[Code] .....
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Oct 14, 2014
I have a requirement to find the greatest/maximum of the given list of Calendar objects in Java.
i.e., 2013/01/26
2014/03/03
2012/02/27
2014/01/15
So the above list of calendar objects are in Arraylist. I need to get the max/greatest among these. Eventually, the answer should be 2014/03/03
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Mar 18, 2014
I have to create a method with the following header :
public static <E extends Comparable<E> > void sort ( ArrayList<E> list , int left, int right)
i also had to create a swap cells method and position of max integer method. and also had to read the preserved data file in with a scanner. I implemented the comparable interface I am having difficulty sorting my list by the area. It has to be in descending order.
Geometric Object class: since it has comparator also am interested if i need to change this?
CODE:
Driver:
public static void main(String[] args) throws IOException, ClassNotFoundException {
Circle c1 = new Circle (4, "red", false);
Circle c2 = new Circle (2, "blue", true);
Circle c3 = new Circle (10, "blue", true);
Rectangle r1 = new Rectangle (10, 6, "yellow", true);
Rectangle r2 = new Rectangle ( 5, 11, "green", true);
ArrayList <GeometricObject> list = new ArrayList();
[Code] ....
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Feb 28, 2014
I'm trying to create my own arraylist using Collection. My program doesn't do anything. Obviously, I haven't a clue.
import java.util.Collection;
import java.util.Iterator;
public class MyArrayList<T> implements java.util.Collection<T> {
private int size = 4;
private T[] mArray;
public MyArrayList(String[] args) {
[Code] ....
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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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Jul 8, 2014
I have stumbled onto a problem with ArrayLists (not sure if nested ArrayList objects would be a more accurate description) ....
As simply put as I can describe it, I have an Inventory class which creates an ArrayList of a Product superclass, which has two subclasses, PerishableProduct and ItemisedProduct.
By default, the program is meant to have a starting inventory, which is why I have added them in the constructor
public class Inventory {
private List<Product> products;
public Inventory() {
addProduct(new Product("Frying pan", 15, 20));
addProduct(new PerishableProduct("Apple", 5.8, 30, 7));
addProduct(new ItemisedProduct("Cereal", 5.8, 0));
// this is where I am having problems. Wanting to add
// objects to the ItemisedProduct's ArrayList for cereal.
}
Within the ItemisedProduct subclass is yet another ArrayList which is meant to hold serial numbers.
public class ItemisedProduct extends Product {
private ArrayList<String> serialNumbers = new ArrayList();
public ItemisedProduct(String name, double price, int qty) {
super(name, price, qty)
[Code] .....
My problem is that I do not know how to populate the serialNumbers ArrayList from the Inventory class' constructor. Because technically, quantity is defined by how many serial numbers are created.
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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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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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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 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 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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Nov 2, 2014
My code is not working properly. The ascending and descending numbers are not showing up. I believe what it is printing is the memory location. In this lab you will be coding a program that will make use of functions to search and sort an array. There will also be a print method, again complete with a full menu system. The Menu options are listed below in the section labeled menu.You will need to set up a hundred (100) position integer (int) array that is defined in main. You will also need an integer (int) variable called size. By doing this, you will have to pass the array and the size to each method you write.
Menu:
The menu should have the following eight options:
1. Fill the array with random numbers (1 -100)
2. Print the array
3. Sort the array in ascending sequence
4. Sort the array in descending sequence
5. Sequential search of the array for a
6. Binary search of the array for a target
7. Exit (this can be option zero if you prefer)
From these seven Options, one can see that six methods will be needed. Each of the six main functionalities above will need a function that does what they say. When printing the array, it is required to print the position number alongside the value. Please start your positions at zero, and not one. When doing the sorting methods, please use two different sorting algorithms. (ie, use a Min Max sort for ascending and an enhanced bubble for descending.)
For the Searching methods: you should ask for the target (number the user is searching for) in the dispatch method. Then pass the target to the search method. The search method should return the position it was found at (0 - Size) OR -1 if it was not found. Then have the appropriate messages print inside of the dispatch method.You could write another function that does this part if you wish to keep your dispatch method cleaner and more organized. But that is up to you.
import java.util.Arrays;
import java.util.Scanner;
import java.util.Random;
public class Lab9 {
public static void main(String[] args)
{
Scanner scan = new Scanner(System.in);
int [] values = new int [100];
[code]....
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May 8, 2014
I'm in the process of doing a module grade book project and I have a working program, however I have to sort the array of students created first of all by name and then if they are identical, by student ID. I've looked at the compareTo method on several websites and I still don't know how to implement it in my code.
My main is as follows;
public class CommandLineTest {
public static void main(String[] args){
String moduleTitle=Input.getString("Enter module title: ");
double cwPercentage=Input.getDouble("Enter coursework percentage: ");
double examPercentage=Input.getDouble("Enter exam percentage: ");
[Code] .....
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Mar 17, 2014
I am trying to find a concise way to write the sort methods for my class. I am supposed to make a program that can sort objects by a number of fields: year, rank, artist and title.
I used an idea from this thread : java - Sorting a collection of objects - Stack Overflow
And I am trying to use the custom comparator for my sort methods. However for some reason, the sortingBy variable fails to recognize any of the enum types.
Whenever I try to set the sortingBy variable equal to one of them, for example:
Java Code:
private Order sortingBy = Year; mh_sh_highlight_all('java');
I get a "Year cannot be resolved to a variable" error.
What I want to be able to do is make it so every time a specific method is called, say, for example sortTitle(), sortingBy will change to Title, then the SongComparator will sort using the case Title.
Is it possible to do this? I can't figure out how to modify SongComparator's object variables that way.
Java Code:
import java.util.Comparator;
public class SongComparator implements Comparator<Song> {
public enum Order {Year, Rank, Artist, Title}
public Order sortingBy;
[Code] .....
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Feb 3, 2015
I am trying to sort an array that I have by alphabetical order but I am having problems. Firstly the code that I have used to sort the array may not even do what I need but havn't got far enough to test it yet so go easy on me . I have read in some places when searching how to do this that I would have to create my own bubble sort in order to achieve this but I was hoping that Java had a built in sort method/function. Secondly I lack the knowledge in java to be able to assign an existing array or even a variable to the newly sorted array as I need the unsorted version with the original name and the newly sorted version as another.
code (This is not all of the code, I decided to include only what I thought was relevant):
import java.util.Arrays;
public class Sentence {
private String words[];
public Sentence(String[] words) { this.words = words; }
@Override
public String toString() {
return "Sentence{" +
"words=" + Arrays.toString(words) +
[Code] ....
Is it possible to shorten the sort function to just this?
public String sorted() {
return Arrays.sort(words);
}
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Nov 24, 2014
I am doing the sorting of multiple fields. This sorting requires to sort the emergency numbers first followed by queue time. However, the sorting is fail, which is the emergency numbers are sorted correctly only but not the queue time. I try to figure out the problem but unfortunately I cannot find where the problem is. Below are the codes for my assignment (Please take note that there is no need to check both ListInterface and LList class) :
public interface ListInterface<T> {
public boolean add(T newEntry);
public boolean add(int newPosition, T newEntry);
public T remove(int givenPosition);
public void clear();
[code]....
This is the attachment of the result that I ran earlier:
Capture.jpg
The first list is before sorting while the second list is after sorting.
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