2 dimensional ArrayList sorting.

Hello,
let me first tell you a bit about my scenario, I am creating an auction program running over RMI, my server passes my client an arraylist of auctions (ListOfAuctions), and these auctions are represented by an arraylist themselves (description, start time, current price, etc)
Where I'm struggling, is I have to be able to sort the top level auctions arraylist (ListOfAuctions), based on an integer element within the individual auctions.
The element I need to sort by is in the same position in the Auction array each time.
Any ideas would be much appreciated, i'm pretty terrible with sort algorithms!
Auction is like so:
element [0] (String)
element [1] (String)
element [2] (Integer)
element [3](Integer)
time Left [4] (Integer) <-- I need to sort 'ListOfAuctions' by this.
element [5] (Integer)
etc.
ListOfAuction is simply an arraylist of the above. I'm too deep rooted into arraylists to use hashtables now so please, no suggestions for using those.
Thanks in Advance
Andy.

I'm committed to this way though, unfortunately..You should tell the one responsible for your project
that by not creating an Auction class and
using java.util.Collection's built-in sort
algorithms, you are creating something that will end
up taking more time to maintain (and even to finish!)
than just doing it the OO-approach and rewriting it
now!Exactly. The way you're trying to do it, you'll have to not only write the code to compare the auctions, but also implement your own sorting algorithm. If you ever need to add another attribute to your auctions, you'll have to make big changes to your sorting algorithm, as well as all the code that handles those lists. If you had an Auction class, adding another attribute wouldn't affect the sorting at all! (unless they were going to be sorted according to that attribute also). It also wouldn't affect any of the code that handles that list of Auctions, since the data associated with auctions is abstracted away, and you don't have to touch it!

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If someone could point to a relevent example, or just show me
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Joe S.

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Hi everyone,
I have a problem I need to sort an ArrayList, that contains other
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ArrayList row=new Arraylist;
ArrayList col=new ArrayList;
col.add(aString);
col.add(anAge);
col.add(aDate);
row.add(col);
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You probably would want to use the following class
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Collections.sort( detailsArrayListLeft, SORT_BY_SEQUENCE );
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Formatting a two-dimensional list...

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Here's a simple sparse grid:
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final int x;
final int y;
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public int hashcode() {
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public class SparseGrid {
private Map<Pair, Integer> grid = new HashMap<Pair, Integer>();
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How can I Sort Enumeration

Hi Guys,
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Sorry typing mistake 'I can' = 'I cannot'
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Tom101 wrote:
I'm having some real trouble trying to replicate this problem. As the program stands at the moment, it reads in a text file and places words into an array list along with an int. The program then copies the strings from the array list into an array, sorts them (using arrays.sort), and then sends them to the output. Now if I enter strings manually to the array it works perfectly. and if I modify my current code so it doesn't include arrays.sort it works perfectly when reading them from a file. Is arrays.sort doing something to it, that triggers JOptionPane to work incorrectly? If you want I can post the method up, however without the rest of the program it wont work the same.Perhaps you could create a new program that goes through the above steps, all of them, and nothing more, and also post the smallest text file to demonstrate the problem. It really should be compilable though, not just a naked method.
This program could be quite simple. The pseudocode could look something like this:
begin
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   sort arraylist
   convert arraylist to array
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endEdited by: petes1234 on Dec 19, 2007 5:57 AM

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after i sort the array...i want to read it at it's original order too...
that mean's i want to have 2 set of array.....1 with the original order...1 with the sorted order..
how do i do that?
let's say i have a container class Club with an array of Names(type String), and a client class...
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thank you.

that mean's i want to have 2 set of array.....1 with
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Message was edited by:
maxfarrar

You can do a two-dimensional ArrayList? That syntax
you wrote didn't work.
I tried doing:
private ArrayList<ArrayList><Integer>> map;
Your syntax is just wrong -- or, this forum software has bug in handling angle brackets.
ArrayList<ArrayList<Integer>>...The closing angle bracket after the second 'ArrayList' is the one generated by the bug. Basically, it should be T<T<T2>> without spaces. Oh, for that matter:
Arraylist<ArrayList<Integer>>

Best efficiently way to transform a large rows ResultSet to Vector

Best efficiently way to transform a large rows ResultSet to a 2-dimensional ArrayList or Vector in a minute ?
If you can help me solve this problem , I 'll give you my duke .

Why don't you use info objects? For example your table is having col1(number),col2(text/varchar),col3(text/varchar), create an info object like this,
class MytableInfo implements java.io.Serializable {
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private String col2;
private String col3;
public MytableInfo(int col1,String col2,String col3) {
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Sudha

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Hello All,
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, but it worked when I just added the set object. Why is this and is there a better way to do all this?
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Please remember the code button/tags.

Need help Sorting an Arraylist of type Object by Name

Hey guys this is my first time posting on this forum so hopefully i do it the right way. My problem is that i am having difficulties sorting an Array list of my type object that i created. My class has fields for Name, ID, Hrs and Hrs worked. I need to sort this Array list in descending order according to name. Name is the last name only. I have used a bubble sort like this:
public static void BubbleSort(TStudent[] x){
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before many time to sort an array of my class TStudent according to GPA. This time though i tried using an Array list instead of just a simple array and i can't figure out how i would modify that to perform the same task. Then i googled it and read about the Collections.sort function. The only problem there is that i know i have to make my own comparator but i can't figure out how to do that either. All of the examples of writing a comparator i could find were just using either String's or just simple Arrays of strings. I couldn't find a good example of using an Array list of an Object.
Anyways sorry for the long explanation and any help anyone could give me would be greatly appreciated. Thanks guys
Edited by: Brian13 on Oct 19, 2007 10:38 PM

ok still having problems I have this line of code to try and all Arrays.sort
Arrays.sort(Employee, TEmployee.FirstNameComparator);Then in my class TEmployee i have
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};Here is the rundown of what i have for this. I have 2 classes. One is called TEmployee and that class holds fields for Name, ID, Hrs Worked, Hourly Rate. Then i have another class called myCompany that holds an ArrayList of type TEmployee. Then i have my main program in a Jframe.
So maybe i am putting them in the wrong spots. The code in TEmployee thats make the comparator is fine. However when i try to call Arrays.sort from class myCompany i get this
cannot find symbol
symbol: method sort (java.util.Array list<TEmployee>.java.util.Comparator
location: class java.util.Arrays
I have to put the comparator in TEmployee right because thats where my fields for Name are? Do i call the arrays.sort from my main program or do i call that from the class myCompany where my ArrayList of TEmployees are stored?
Again guys thanks for any help you could give me and if you need any code to see what else is going on just let me know.

Can I sort an ArrayList basd on a data member?

Hello everyone.
Currently my program stores a lot of objects in an ArrayList.
Each of these objects has the following data members:
public class ClassEntity
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     private String idFieldName;
     //ENGLISH VERSION
     private String englishClassName;
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}I have the following data structure:
List<ClassEntity> classEntityList = new ArrayList<ClassEntity>();Now is there a way to order the Objects inside the ArrayList so they are in alphabetical order based on the englishFieldName data member?
I currently iterate through the List and write it to a file and the List is out of order so the writing to file is out of order.
I saw collections has a .sort() method, but I'm not sure how I would tell the .sort() to sort based on englishFieldName. In C++ I would overload the < operator I'm still new to data structures in Java though.
Thanks!

Implement the Comparable Interface in your class, as my example in this posting shows:
http://forum.java.sun.com/thread.jspa?forumID=31&threadID=598401

Problems with sort, search and write objects o an ArrayList

Hi
Lets say that i have two subclasses (the program is not finished so in the end it can be up to 34 classes) of an abstract superclass. I also got one class which basicly is a register in which i've created an ArrayList of the type <abstractClass>. This means that i store the two subclasses in the arrayList. no problems so far i think (at least eclipse doesn't mind).
1. now, i want to be able to sort the arrayList aswell as search thorugh it. I've tried Collections.sort(arrayList) but it doesn't work. So i have no idea how to solve that.
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it runs but it returns +"false"+ even if i create an object with the exact same properties.
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Any ideas?
Thank you!
Anton

lavalampan wrote:
Hi
Lets say that i have two subclasses (the program is not finished so in the end it can be up to 34 classes) of an abstract superclass. I also got one class which basicly is a register in which i've created an ArrayList of the type <abstractClass>. This means that i store the two subclasses in the arrayList. no problems so far i think (at least eclipse doesn't mind).
1. now, i want to be able to sort the arrayList aswell as search thorugh it. I've tried Collections.sort(arrayList) but it doesn't work. So i have no idea how to solve that. Create a custom comparator.
>
2.The search-method i made doesn't work as good as i hoped for either. I ask the user to first decide what to search for (choose subclass) and then input the same properties as the subclass we search for. I create a new object of the subclass with these inputs and try arrayList.contains(subClassObject)
it runs but it returns +"false"+ even if i create an object with the exact same properties.Implement hashCode and equals.
>
3. If i want to write this arrayList to a txtFile so i can import it another time. Which is the best method? first i just thought i'd convert the arrayList to string and then print every single object to a textfile as strings. that worked but i have no good idea how to import that into the same arrayList later. Then i found ObjectOutputStream and import using inputStream.nextObject(). But that doesn't work :(Depends on what your requirement is, but yes, Serialization might work for you. Your classes should in that case implement Serializable.
Kaj

Need help sorting an ArrayList of strings by an in common substring

I'm trying to sort a .csv file, which I read into an ArrayList as strings. I would like to sort by the IP address within the string. Can someone please help me figure out the best way to sort these strings by a common substring each has, which is an IP address.
I'm pretty sure that I need to use Collections some how, but I don't know where to begin with them besides trying to look online for help. I had no luck finding any good examples, so I came here as a last resort.
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You need to write your own Comparator class. In the compare() method you substring out the two IP addresses, compare them and return appropriate value. Then you call Collections.sort() and pass your list and comparator.

2 dimensional ArrayList sorting.

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