Populating an ArrayList of ArrayList

Hi,
Could anyone pls help me with this one. I'm trying with the following code to populate an ArrayList (alDataRows) which contain several ArrayLists(alCols). variable rsResultSet is the resultset from which I want to populate this arraylist and variable intNumberOfColumns is the number of columns I have in that resultset.
What's happening is that, finally, I'm getting the last record only in this arraylist. Also, if I don't do alCols.clear(), alCols is having (number of columns * number of rows) records which is erroneous.
Could somebody pls correct me.
thanks much in advance!
=====================
ArrayList alCols = new ArrayList();
ArrayList alDataRows = new ArrayList();
int intRowPos = 0;
while (rsResultSet.next())
alCols.clear();
for (int i=0; i < intNumberOfColumns ; i++)
alCols.add(i, rsResultSet.getString(i+1));
alDataRows.add(intRowPos,alCols);
intRowPos++;
//System.out.println("intRowPos = " +intRowPos);
}

Could anybody pls help me on this one?
I have the following to populate an arrylist(alDataRows) of arraylists(alCols).
ArrayList alCols = null;
ArrayList alDataRows = new ArrayList();
int intRowPos = 0;
while (rsResultSet.next())
alCols = new ArrayList();
for (int i=0; i < intNumberOfColumns ; i++)
{ alCols.add(i, rsResultSet.getString(i+1));
alDataRows.add(intRowPos,alCols);
intRowPos++;
Now how do I retrieve a particular value within it?
Is it like (String)alDataRows.get(rowindex).get(colindex).
This is not compiling.
thanks much

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Populating an arraylist

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     at com.ibm.ws.webcontainer.servlet.ServletInstanceReference.dispatch(ServletInstanceReference.java:40)
     at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.handleWebAppDispatch(WebAppRequestDispatcher.java:1044)
     at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.dispatch(WebAppRequestDispatcher.java:600)
     at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.include(WebAppRequestDispatcher.java:254)
     at com.ibm.wps.services.dispatcher.DispatcherServiceImpl.handleRequest(DispatcherServiceImpl.java:89)
     at com.ibm.wps.services.dispatcher.DispatcherServiceImpl.include(DispatcherServiceImpl.java:50)
     at com.ibm.wps.services.dispatcher.Dispatcher.include(Dispatcher.java:44)
     at com.ibm.wps.engine.templates.screens.Default.render(Default.java:91)
     at com.ibm.wps.engine.templates.ScreenTemplate.render(ScreenTemplate.java:61)
     at com.ibm.wps.engine.tags2.ScreenRenderTag.doStartTag(ScreenRenderTag.java:89)
     at org.apache.jsp._Default._jspService(Default.jsp :768)
     at com.ibm.ws.webcontainer.jsp.runtime.HttpJspBase.service(HttpJspBase.java:89)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
     at com.ibm.ws.webcontainer.jsp.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:344)
     at com.ibm.ws.webcontainer.jsp.servlet.JspServlet.serviceJspFile(JspServlet.java:683)
     at com.ibm.ws.webcontainer.jsp.servlet.JspServlet.service(JspServlet.java:781)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
     at com.ibm.ws.webcontainer.servlet.StrictServletInstance.doService(StrictServletInstance.java:110)
     at com.ibm.ws.webcontainer.servlet.StrictLifecycleServlet._service(StrictLifecycleServlet.java:174)
     at com.ibm.ws.webcontainer.servlet.IdleServletState.service(StrictLifecycleServlet.java:313)
     at com.ibm.ws.webcontainer.servlet.StrictLifecycleServlet.service(StrictLifecycleServlet.java:116)
     at com.ibm.ws.webcontainer.servlet.ServletInstance.service(ServletInstance.java:283)
     at com.ibm.ws.webcontainer.servlet.ValidServletReferenceState.dispatch(ValidServletReferenceState.java:42)
     at com.ibm.ws.webcontainer.servlet.ServletInstanceReference.dispatch(ServletInstanceReference.java:40)
     at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.handleWebAppDispatch(WebAppRequestDispatcher.java:1044)
     at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.dispatch(WebAppRequestDispatcher.java:600)
     at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.include(WebAppRequestDispatcher.java:254)
     at com.ibm.wps.services.dispatcher.DispatcherServiceImpl.handleRequest(DispatcherServiceImpl.java:89)
     at com.ibm.wps.services.dispatcher.DispatcherServiceImpl.include(DispatcherServiceImpl.java:50)
     at com.ibm.wps.services.dispatcher.Dispatcher.include(Dispatcher.java:44)
     at com.ibm.wps.engine.templates.themes.Default.render(Default.java:103)
     at com.ibm.wps.engine.templates.ThemeTemplate.render(ThemeTemplate.java:67)
     at com.ibm.wps.engine.phases.WPRenderPhase.processRendering(WPRenderPhase.java:312)
     at com.ibm.wps.engine.phases.WPRenderPhase.execute(WPRenderPhase.java:135)
     at com.ibm.wps.state.phases.AbstractRenderPhase.next(AbstractRenderPhase.java:106)
     at com.ibm.wps.engine.phases.WPAbstractRenderPhase.next(WPAbstractRenderPhase.java:93)
     at com.ibm.wps.engine.Servlet.callPortal(Servlet.java:713)
     at com.ibm.wps.engine.Servlet.doGet(Servlet.java:562)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:740)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
     at com.ibm.ws.webcontainer.servlet.StrictServletInstance.doService(StrictServletInstance.java:110)
     at com.ibm.ws.webcontainer.servlet.StrictLifecycleServlet._service(StrictLifecycleServlet.java:174)
     at com.ibm.ws.webcontainer.servlet.IdleServletState.service(StrictLifecycleServlet.java:313)
     at com.ibm.ws.webcontainer.servlet.StrictLifecycleServlet.service(StrictLifecycleServlet.java:116)
     at com.ibm.ws.webcontainer.servlet.ServletInstance.service(ServletInstance.java:283)
     at com.ibm.ws.webcontainer.servlet.ValidServletReferenceState.dispatch(ValidServletReferenceState.java:42)
     at com.ibm.ws.webcontainer.servlet.ServletInstanceReference.dispatch(ServletInstanceReference.java:40)
     at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:76)
     at com.ibm.wps.state.filter.StateCleanup.doFilter(StateCleanup.java:86)
     at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:132)
     at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:71)
     at com.ibm.wps.mappingurl.impl.URLAnalyzer.doFilter(URLAnalyzer.java:216)
     at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:132)
     at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:71)
     at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.handleWebAppDispatch(WebAppRequestDispatcher.java:1040)
     at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.dispatch(WebAppRequestDispatcher.java:600)
     at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.forward(WebAppRequestDispatcher.java:201)
     at com.ibm.ws.webcontainer.srt.WebAppInvoker.doForward(WebAppInvoker.java:125)
     at com.ibm.ws.webcontainer.srt.WebAppInvoker.handleInvocationHook(WebAppInvoker.java:286)
     at com.ibm.ws.webcontainer.cache.invocation.CachedInvocation.handleInvocation(CachedInvocation.java:71)
     at com.ibm.ws.webcontainer.cache.invocation.CacheableInvocationContext.invoke(CacheableInvocationContext.java:116)
     at com.ibm.ws.webcontainer.srp.ServletRequestProcessor.dispatchByURI(ServletRequestProcessor.java:186)
     at com.ibm.ws.webcontainer.oselistener.OSEListenerDispatcher.service(OSEListener.java:334)
     at com.ibm.ws.webcontainer.http.HttpConnection.handleRequest(HttpConnection.java:56)
     at com.ibm.ws.http.HttpConnection.readAndHandleRequest(HttpConnection.java:624)
     at com.ibm.ws.http.HttpConnection.run(HttpConnection.java:458)
     at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:912)Then I changed the <f:selectItems/> little bit like
<f:selectItems value="#selectItems.gfogBean.northAmericaList.toArray}"/>Then there was no error ,but the dropdown was null.
Again I modifed the <f:selectItems/> tag in this way:
<f:selectItems value="#{selectitems.gfogBean.northAmericaList.testBeanValue.testBeanValue.toArray}"/>then the dropdown appeared but the values were showing up twice.
Can anybody give me solution to this problem.Even a custom converter or a custom component could solve this problem.. \n
Because in my application, we are not populating the arraylists with SelectItem type.

The perInfoAll list should be declared locally in getPerInfoAll(), otherwise it grows every time you call it.
#{e.id};Remove the semicolon, unless you want to see it on the page, which doesn't seem right. Try <h:outputText value="#{e.id}"/> instead. Only certain types of children are supported inside h:column.

GA Help Needed Urgently

Hi,
I'm stuck on how exactly to define the selectParent() method (the Selection method) because I have to take out samples of size 5 (the tournament size) from the population and then order those chromosomes ( in the contenders ArrayList) in order of fitness (the lower the fitness the better). But since I'm working with ArrayLists and since I have to extract each Chromosome object from the contender Arraylist, somehow call the fitness() method on each Chromosome, and then sort in order of fitness (lowest first), then store the 2 Chromosomes with the lowest fitness into a parent ArrayList, I'm lost with how to do this. Any ideas on this please? What's the simplest way of doing it?
Here's the code I have done - the commented stuff is the stuff I have tried to code to do the sorting, but it's all useless now. I am almost in a giving up situation here - Can anyone come up with a solution for how the tournament selection sort would be done in order for my code to run - or some sort of sorting algorithm to order the fitness from lowest to highest as this is the part I am find most trouble with - the thing I don't understand is that because the fitness value of each Chromosome is not stored anywhere (like a variable or ArrayList), how am I able to order the fitnesses from every sample of 5? PLEASE HELP URGENTLY :-(
import java.util.ArrayList;
import java.util.Random;
import java.util.Collections;
import java.math.*;
import java.util.Collection;
class Population {
Database d = new Database();
Random rand = new Random();
ArrayList population = new ArrayList();
ArrayList parents = new ArrayList();
ArrayList contenders = new ArrayList();
public void initialPopulation() {
    double[] reuters = {
        8.0, 9.0, 12.5, 11.5, 6, 7, 4, 2, 3, 4, 3, 5, 5.5};
    Share s1 = new Share(reuters);
    d.addShare(s1);
    for (int i = 0; i < 10; i++) {
      Chromosome c = new Chromosome(rand);
      c.setDatabase(d);
      population.add(c);
      System.out.println("Chromosome Weights are: " + c);
      System.out.println("Chromosome Fitness Value is: " + c.fitness(0));
      System.out.println();
    System.out.println(population.size());
    System.out.println(population.toString());
    System.out.println();
//     System.out.println(d);
public ArrayList selectParents(int tournamentSize) {
    // Get as many chromosomes as specified by tournament size
    for (int i = 0; i < tournamentSize; i++) {
      contenders.add(i, population.get(i));
    // Sort the sub-population in order of fitness *****Having Huge Problems Here***
/* double[] fitnessVals = new double[5];
    double[] temp = new double[5];
    ArrayList tempArrayList = new ArrayList();
    for (int i = 0; i < (contenders.size()); i++) {
      Chromosome temp1 = (Chromosome)contenders.get(i);
      fitnessVals[i] = temp1.fitness(0); }
System.out.println((fitnessVals[0]) +","+ (fitnessVals[1]));
   for (int i = 0; i < (contenders.size()); i++) {
    if (fitnessVals[i] > fitnessVals[i+1])
      temp[i] = fitnessVals[i + 1];
      fitnessVals[i + 1] = fitnessVals;
fitnessVals[i] = temp[i];
tempArrayList.add(contenders.get(i + 1));
contenders.set(i+1, contenders.get(i));
contenders.set(i, tempArrayList.get(i));
else {}
// Collections.max((Collection)contenders.get(0));
// System.out.println(contenders.toString());
/* public void sortInOrderOfFitness(Comparable ArrayList ) {
for (int i = 0; i < contenders.size(); i++) {
Collections.sort(contenders);
System.out.println(contenders); ****Up to Here is Where I'm Lost***
// Return the best two
parents.add(contenders.get(0));
parents.add(contenders.get(1));
System.out.println(parents.toString());
System.out.println(contenders.toString());
return parents;
public static void main(String args[]) {
Population p = new Population();
p.initialPopulation();
p.selectParents(5);
import java.util.ArrayList;
import java.util.Random;
class Chromosome
{ int[] bit = new int[12];
Database db;
Chromosome(Random rand)
{ for (int i = 0; i < 12; i++)
{ bit[i] = rand.nextInt(6); }
public String toString()
{ String res = "";
for (int i = 0; i < 12; i++)
{ res = res + bit[i] + ","; }
return res;
public void setDatabase(Database d)
{ db = d; }
public double fitness(int share)
{ double prediction = 0;
int divisor = 0;
Share sh = db.getShare(share);
for (int i = 0; i < 12; i++)
{ prediction = prediction + bit[i]*sh.getPrice(i);
divisor = divisor + bit[i];
if (divisor != 0)
{ prediction = prediction/divisor; }
else
{ prediction = 0; }
System.out.println("Prediction Value is: " + prediction);
double actualPrice = sh.getPrice(12);
return Math.abs(prediction - actualPrice);
import java.util.ArrayList;
import java.util.Random;
class Database
{ ArrayList sharedata = new ArrayList();
public void addShare(Share s)
{ sharedata.add(s); }
public Share getShare(int i)
{ return (Share) sharedata.get(i); }
class Share
{ double[] prices = new double[13];
Share(double[] p)
{ prices = p; }
double getPrice(int i)
{ return prices[i]; }

No you're not I'm still hereI was making a point that it's rude to flag your
questions as urgent. As you can see, a lot of the
people who answer questions tend to ignore such
posts.
I didn't realise this until now since you've pointed it out - I saw other posts with 'urgent' and felt mine really was urgent which is why I did this.
>
, any ideas??Yes, throw that commented method away and read up on
how to use Java's collections API to properly sort a
list/collection of objects:
http://java.sun.com/docs/books/tutorial/collections/in
terfaces/order.html
Good luck.I'm going to have a good look at this now. Hopefully I'll be able to get somewhere.

Data table vanishing on reload

Hi,
I have in the jsp a table populated by arraylist. The bean used is request scope and cannot be kept as session scope. When I view the page for the first time the list comes properly. But subsequent operation on the same page the list doesnt appears. On subsequent opertaion I dont repopulate because I think jsf should do the same for me.
Could anyone help me on this?
Regards,
KP

I have seen similar behavior when nested collections are used to populate nested datatables and the bean had a scope of request. Outside those nested cases, I did not experience the behavior you are describing with request bean. I think it is a bug. Use session scope as a workaround. Unfortunately you will need to manually remove from session scope in case needed for performance reasons, ...etc

PLEASE HELP ME. THIS PROGRAM IS KILLING ME.

Hi. I am getting so sick of this program. I have been trying to do it for the past couple of weeks and I am getting nowhere. I really wish someone can help me on it ... like totaly help me on it. I am getting so frustrated. I would appreciate all the help.
This is the program:
In Belageusia, a plorg has these properties:
Data:
     A plorg has a name
     A plorg has a contentment index (CI), which is an integer between 0 and 100
The population of plorgs in Belagersia is further subdivided into three mutually exclusive classes: Plebeians, Equidians, and Elitians.
A Plorg?s stature is completely determined by their contentment index and witht that designation comes certain burdens and/or advantages.
Plebeians have a contentment index in [0, 24].
Each new Plebeian is welcomed with a contentment index of 2 and burdened with a debt of $10.00
Plebeians never manage to break even, so they have no taxes imposed upon them. Furthermore, since they can never get out debt, they cannot accumulate any wealth.
Equidians have a contentment index in [25, 75]
Each new Equidian is welcomed with a contentment index of 50 and burdened with taxes of $20.00
Equidians have taxes imposed upon them. Furthermore, since they do manage to break even, they have no debt. However, since they only manager to break even, they do not accumulate any wealth.
Elitians have a contentment index in [76, 100]
Each new Elitian is welcomed with a contentment index of 87 and burdened with taxes of $20.00, but also provided with a ?silver spoon? of $30.00 in accumulated wealth.
Elitians manage to expand upon their wealth, sot hey have taxes imposed upon them. Furthermore, since they are accumulating wealth, they have no debt.
At each interim time epoch the population of Belageusia retracts with a death rate randomly selected between 0% and 10%. If a plorg survives the purge, they have an opportunity to move one class higher and/or one class lower. However, remember that a plorg?s name is final. It never changes.
For Plebeians this is transition is determined by randomly selecting a CI in [0, 49]. If this new CI is les than 25 then the plorg remains a Plebeian, with this newly assigned CI, and their debt increases 3.7%. If this new CI is in [25, 49], the Plebeian ascends to a Equidian, with this newly assigned CI, their debt is forgiven, but taxes of $20 are assessed.
For Equidians this is determined by randomly selecting a CI in [0,100].
If this new CI is in [25, 75] then the plorg remains a Equidian, with this newly assigned CI, but their taxes are increased 6.1%.
If this new CI is in [0, 24] then the plorg becomes a Plebeian, with this newly assigned CI, their taxes are forgiven, but they are burdened with a debt of $10.00.
If this new CI is in [76, 100] then the plorg becomes a Plebeian, with this newly assigned CI, but their taxes are increased 6.1%. However, they are bewtowed a wealth of $30.00.
For Eletians this is determined by randomly selecting a CI in [51, 100]. If this new CI is greater than 76 then the plorg remains an Eletian, with this newly assigned CI, their taxes increase 6.1% and their wealth increases 4.9%. If this new CI is in [51, 75], then this plorg becomes an Equidian, with this newly assigned CI, their wealth is eliminated, and their taxes are increased 6.1%.
At each time epoch, the population of Belageusia at a birth rate randomly selected between 0% and 10%. A randomly chosen number between 0-100 determines each newly born plorg?s stature. If this random number is in the range 0-24, create a new Plebeian. In the range 25-75, create a new Equidian, and if in the range 76-100, create a new Elitian.
We are supposed to output the population characteristics of Belageusia, after 1000 time epochs.
This is the code that I wrote down but got no where with:
import javax.swing.*;
import java.util.*;
import java.text.*;
public class Belageusiaplorg
     public static void main (String[] args)
          ArrayList Plebs = new ArrayList(350);
          ArrayList Equids = new ArrayList(600);
          ArrayList Elits = new ArrayList(350);
          ArrayList Holding = new ArrayList(600);
          for (int i=0; i<25; i++)
               Plebs.add(new plebian());
          for (int i=0; i<50; i++)
               Equids.add(new equidian());
          for (int i=0; i<25; i++)
               Elits.add(new Elitian());
          long population = Plebs.size() + Equids..size() + Elits.size();
          System.out.println("Current Belageusia Population is "+population);
          System.out.println("Current Plebeians Population is "+Plebs.size);
          System.out.println("Current Equidians Population is "+Equids.size);
          System.out.println("Current Elitians Population is "+Elits.size);
          Random generator = new Random();
          int x = generator.nextInt(11);
          for (int j=0; j=plebs.size(); j++)
               System.out.println(Plebs.g(j));
          long Equids_size = Equids.size();
          long Elits_size = Elits.size();
          for(int j=1; j<Plebs.size(); j++)
               Plebian e = (Plebian) Plebs.get(j);
               int new_ci = generator.nextInt(50);
               if (new_ci < 25)
                    e.setCI(new_ci);
                    e.raiseDebt();
               else
                    Plebs.rename(j);
                    Equids.add(new Equidian(e.getName().newCI));
                    j++;
          for(int j=0; j < Equids.size; j++)
               Equidian e = (Equidian) Equids.get(j);
               int newCI = generator.nextInt(101);
               if(new_ci < 25)
                    Equids.remove(j);
                    Plebs.add(nwe Plebian(e.getName().new_ci));
                    Equids_size --;
                    j++;
               else
               if (new_ci > 75)
                    Equids.remove(j);
                    Elitian f = new Elitian(e.getName(),new_ci,e.getTaxes());
                    Elits.add(f);
                    Equids_size --;
                    j--;
               else
                    e.setCI(new_CI);
                    e.raiseTaxes();
          for (int j=0; j<Elits.size; j++)
               Elitian e = (Elitian) Elits.get(j);
               int ci = e.getCI();
               int r = generator.nextINT(50);
               int new_ci = 51+r;
               if(new_ci > 75)
                    e.setCI(new_ci);
                    e.raisetaxes();
                    e.raisewealth();
               else
                    Elitians.remove(j);
                    Equidian g = new Equidian(e.getName(), new_ci);
                    g.raisetaxes();
                    Equids.add(g);
                    Elits_size --;
                    j--;
          if(deathrate != 0)
               int multiple = 100/deathrate;
               int count 1;
               for (int j=0; j=Plebs.size(); j++)
                    if(count % multiple == 0)
                         Plebs.remove(j);
                         j--;
                    count++;
class Plorg
     private final String name;
     private int CI;
     private static long nextID = 1;
     public Plorg()
          name = "Plorg" + nextID;
          nextID++;
     public Plorg(int CI)
          name = "Plorg" + nextID;
          nextID++;
          this.CI = CI;
     public Plorg (String name, int CI)
          this.name = name;
          this.CI = CI;
     public void setCI(int new_CI)
          CI = new_CI;
     public String getName()
          return name;
     public int getCI()
          return CI;
     public Plorg Plebs()
     public Plorg Equids()
     public Plorg Elits()

Sounds a lot like a homework question to me. Still it was interesting enough to try out. I have not tried to change your code, just made one of my own. Here is my solution. I have made the Plorg class an inner class of the Belageusia. This is just so I dont have to put up two java files. You could easily split it into two though.
import java.util.Random;
import java.util.ArrayList;
import java.util.Iterator;
* @author Jonathan Knight
public class Belageusia
    /** Random number generator - Seeded with the current time. */
    private static Random random = new Random(System.currentTimeMillis());
    /** A list of all of the Plorgs */
    private ArrayList population = new ArrayList();
    /** A list of all of the Plebians. */
    private ArrayList plebians = new ArrayList();
    /** A list of all of the Equidians. */
    private ArrayList equidians = new ArrayList();
    /** A list of all of the Elitians. */
    private ArrayList elitians = new ArrayList();
    /** A count of the Epochs that have passed */
    private int epochs = 0;
     * Main method.
     * Create a new world of Belageusia and run it for 1000 epochs.
    public static void main(String[] args)
        Belageusia world;
        world = new Belageusia();
        for (int i = 0; i < 1000; i++)
            world.epoch();
        System.out.println("The Belageusia population after 1000 epochs");
        world.printPopulation();
     * Create a new World of Belageusia and create some Plorgs to live there.
     * The world will be created with 25 Plebians, 50 Equidians and 25 Elitians.
    public Belageusia()
        for (int i = 0; i < 25; i++)
            plebians.add(Plorg.createPlebian());
        for (int i = 0; i < 50; i++)
            equidians.add(Plorg.createEquidian());
        for (int i = 0; i < 25; i++)
            elitians.add(Plorg.createElitian());
     * Print the current population to System.out
    public void printPopulation()
        int total;
        int plebianCount;
        int equidianCount;
        int elitianCount;
        plebianCount = plebians.size();
        equidianCount = equidians.size();
        elitianCount = elitians.size();
        total = plebianCount + equidianCount + elitianCount;
        System.out.println("Current Belageusia population is " + total);
        System.out.println("Current Plebian population is " + plebianCount);
        System.out.println("Current Equidian population is " + equidianCount);
        System.out.println("Current Elitian population is " + elitianCount);
     * At each interim time epoch the population of Belageusia retracts with a death rate
     * randomly selected between 0% and 10%. If a plorg survives the purge, they have an
     * opportunity to move one class higher and/or one class lower. However, remember that
     * a plorgs name is final. It never changes.
     * For Plebeians this transition is determined by randomly selecting a CI in [0, 49].
     * If this new CI is les than 25 then the plorg remains a Plebeian, with this newly assigned CI,
     * and their debt increases 3.7%. If this new CI is in [25, 49], the Plebeian ascends to a
     * Equidian, with this newly assigned CI, their debt is forgiven, but taxes of $20 are assessed.
     * For Equidians this is determined by randomly selecting a CI in [0,100].
     * If this new CI is in [25, 75] then the plorg remains a Equidian, with this newly assigned CI,
     * but their taxes are increased 6.1%.
     * If this new CI is in [0, 24] then the plorg becomes a Plebeian, with this newly assigned CI,
     * their taxes are forgiven, but they are burdened with a debt of $10.00.
     * If this new CI is in [76, 100] then the plorg becomes a Plebeian, with this newly assigned CI,
     * but their taxes are increased 6.1%. However, they are bewtowed a wealth of $30.00.
     * For Eletians this is determined by randomly selecting a CI in [51, 100].
     * If this new CI is greater than 76 then the plorg remains an Eletian, with this newly assigned CI,
     * their taxes increase 6.1% and their wealth increases 4.9%. If this new CI is in [51, 75],
     * then this plorg becomes an Equidian, with this newly assigned CI, their wealth is eliminated,
     * and their taxes are increased 6.1%.
     * At each time epoch, the population of Belageusia at a birth rate randomly selected between 0% and 10%.
     * A randomly chosen number between 0-100 determines each newly born plorg?s stature.
     * If this random number is in the range 0-24, create a new Plebeian. In the range 25-75, create a new Equidian,
     * and if in the range 76-100, create a new Elitian.
    public void epoch()
        ArrayList newPlebians = new ArrayList();
        ArrayList newEquidians = new ArrayList();
        ArrayList newEletians = new ArrayList();
        Iterator it;
        Plorg plorg;
        int deathRate;
        double deathCount;
        int birthRate;
        double birthCount;
        int population;
        int subClass;
        int newCI;
        int kill;
        epochs++;
        System.out.println("Epoch = " + epochs);
        printPopulation();
        population = plebians.size() + equidians.size() + elitians.size();
        // The death rate is random 0 to 10%
        deathRate = random.nextInt(11);
        // work out the death count. population is cast to a double to avoid rounding errors
        deathCount = (double)population * deathRate / 100;
        // round up the result. We do this as once the population falls below 10
        // we would never kill anything
        deathCount = Math.ceil(deathCount);
        // We now work out the birth rate based on the population before we kill
        // anything otherwise the population tends to go down and down
        // The birth rate is random 0 to 10%
        birthRate = random.nextInt(11);
        // work out the birth count. population is cast to a double to avoid rounding errors
        birthCount = Math.ceil((double)population * birthRate / 100);
        // As with the deathCount round up the result.
        // We do this as once the population falls too low we would never create any more
        birthCount = Math.ceil(birthCount);
        System.out.println("About to kill " + deathRate + "% which is " + deathCount + " Plorgs out of " + population);
        for(int i=0; i<deathCount; i++)
            // get a random number between 0 and 2
            kill = random.nextInt(population);
            population--;
            // kill the specified Plorg
            if( kill < plebians.size() )
                // kill a random Plebian
                plebians.remove( random.nextInt(plebians.size()) );
            else if( kill < plebians.size() + equidians.size() )
                // kill a random Equidian
                equidians.remove( random.nextInt(equidians.size()) );
            else
                // kill a random Elitian
                elitians.remove( random.nextInt(elitians.size()) );
        System.out.println("Transitioning Plebians");
        // Transition period for Plebians
        it = plebians.iterator();
        while ( it.hasNext() )
            plorg = (Plorg) it.next();
            // select a new CI from 0 to 49 at random
            newCI = random.nextInt(50);
            plorg.setCI(newCI);
            if( newCI < 25 )
                // Oh dear, this one stays as a Plebian; increase its dept by 3.7%
                plorg.setDept( plorg.getDept() * 1.037 );
            else
                // Congratulations this one is now an Equidian
                newEquidians.add(plorg);
                // remove from the Plebian list.
                // NOTE we must do the remove via the Iterator
                it.remove();
                plorg.setDept(0);
                plorg.setTaxes(20);
        System.out.println("Transitioning Equidians");
        // Transition period for Equidians
        it = equidians.iterator();
        while ( it.hasNext() )
            plorg = (Plorg) it.next();
            // select a new CI from 0 to 100 at random
            newCI = random.nextInt(101);
            plorg.setCI(newCI);
            if( newCI < 25 )
                // Oh dear, this one becomes a Plebian
                newPlebians.add(plorg);
                // remove from the Equidian list.
                // NOTE we must do the remove via the Iterator
                it.remove();
                plorg.setDept( 10 );
                plorg.setTaxes(0);
            else if( newCI < 25 )
                // This one stays as an Equidian; increase its taxes by 6.1%
                plorg.setTaxes( plorg.getTaxes() * 1.061 );
            else
                // Congratulations this one is now an Eletian
                newEletians.add(plorg);
                // remove from the Equidian list.
                // NOTE we must do the remove via the Iterator
                it.remove();
                plorg.setWealth(30);
                // Increase its taxes by 6.1%
                plorg.setTaxes( plorg.getTaxes() * 1.061 );
        System.out.println("Transitioning Elitians");
        // Transition period for Eletians
        it = plebians.iterator();
        while ( it.hasNext() )
            plorg = (Plorg) it.next();
            // Always increase taxes by 6.1%
            plorg.setTaxes( plorg.getTaxes() * 1.061 );
            // select a new CI from 51 to 100 at random
            newCI = 51 + random.nextInt(50);
            plorg.setCI(newCI);
            if( newCI > 76 )
                // This one stays as an Eletian; increase its wealth by 4.9%
                plorg.setWealth( plorg.getWealth() * 1.049 );
            else
                // Oh dear, this one becomes an Equidian
                newEquidians.add(plorg);
                // remove from the Plebian list.
                // NOTE we must do the remove via the Iterator
                it.remove();
                // emove its wealth
                plorg.setWealth(0);
        // now assign the Plorgs that are transitioning
        plebians.addAll(newPlebians);
        equidians.addAll(newEquidians);
        elitians.addAll(newEletians);
        System.out.println("Creating " + birthRate + "% new Plorgs from " + population + " which is " + birthCount);
        //create the new Plorgs
        for (int i = 0; i < birthCount; i++)
            // get a random number between 0 and 100
            subClass = random.nextInt(101);
            // create the specified Plorg
            if( subClass <= 24 )
                plorg = Plorg.createPlebian();
                plebians.add(plorg);
            else if( subClass >= 25 && subClass <= 75 )
                plorg = Plorg.createEquidian();
                equidians.add(plorg);
            else
                plorg = Plorg.createElitian();
                elitians.add(plorg);
    public static class Plorg
        /** Identifier used to generate unique names */
        private static int id = 0;
        /** The Plorgs name */
        private final String name;
        /** The level of wealth for this Plorg */
        private double wealth = 0;
        /** The level of dept for this Plorg */
        private double dept = 0;
        /** The level of taxes for this Plorg */
        private double taxes = 0;
        /** This Plorgs contentment index */
        private int ci = 0;
        /** Create a new Plorg with the given CI.
         * This is a private constructor. The only way for a program to
         * create new Plorgs is by calling either createPlebian(),
         * createEquidian() or createElitian().
         * @param ci
        private Plorg(int ci)
            // Generate a unique name and iincrement the ID
            this.name = "Plorg" + id++;
            // assign the CI
            this.ci = ci;
         * Create a new Plebian.
         * Plebeians have a contentment index in [0, 24].
         * Each new Plebeian is welcomed with a contentment index of 2 and burdened
         * with a debt of $10.00. Plebeians never manage to break even, so they have
         * no taxes imposed upon them. Furthermore, since they can never get out debt,
         * they cannot accumulate any wealth.
         * @return a new Plebian.
        public static Plorg createPlebian()
            Plorg plebian;
            plebian = new Plorg(2);
            plebian.setDept(10);
            return plebian;
         * Create a new Equidian
         * Equidians have a contentment index in [25, 75].
         * Each new Equidian is welcomed with a contentment index of 50 and burdened
         * with taxes of $20.00. Equidians have taxes imposed upon them. Furthermore,
         * since they do manage to break even, they have no debt. However, since they
         * only manager to break even, they do not accumulate any wealth.
         * @return a new Equidian.
        public static Plorg createEquidian()
            Plorg equidian;
            equidian = new Plorg(50);
            equidian.setTaxes(20);
            return equidian;
         * Create a new Elitian.
         * Elitians have a contentment index in [76, 100].
         * Each new Elitian is welcomed with a contentment index of 87 and burdened
         * with taxes of $20.00, but also provided with a ?silver spoon? of $30.00 in
         * accumulated wealth. Elitians manage to expand upon their wealth, so they
         * have taxes imposed upon them. Furthermore, since they are accumulating
         * wealth, they have no debt.
         * @return a new Elitian.
        public static Plorg createElitian()
            Plorg equidian;
            equidian = new Plorg(87);
            equidian.setWealth(30);
            equidian.setTaxes(20);
            return equidian;
         * Returns this Plorgs name.
        public String getName()
            return name;
         * Returns the CI of this Plorg.
        public int getCI()
            return ci;
         * Set the new Contentment index for this Plorg
         * @param ci
        public void setCI(int ci)
            this.ci = ci;
         * Returns the Dept of this Plorg
         * @return
        public double getDept()
            return dept;
         * Set the dept of this Plorg.
         * @param dept - the new dept for the Plorg.
        public void setDept(double dept)
            this.dept = dept;
         * Returns the wealth of this Plorg.
        public double getWealth()
            return wealth;
         * Sets the wealth of this Plorg.
         * @param wealth - the new wealth of this Plorg.
        public void setWealth(double wealth)
            this.wealth = wealth;
         * Returns the taxes of this Plorg.
        public double getTaxes()
            return taxes;
         * Set the taxes of this Plorg.
         * @param taxes - the new taxes for this Plorg.
        public void setTaxes(double taxes)
            this.taxes = taxes;
         * Check for equality. If the object specified is a Plorg with the same name as this
         * Plorg they are deemed to be equal.
         * @param o - The object to check
        public boolean equals(Object o)
            if ( this == o ) return true;
            if ( !(o instanceof Plorg) ) return false;
            final Plorg plorg = (Plorg) o;
            if ( name != null ? !name.equals(plorg.name) : plorg.name != null ) return false;
            return true;
         * Create a Hash Code for this Plorg
        public int hashCode()
            return (name != null ? name.hashCode() : 0);
}

Please decode this error..

i've a page that displays records from the database..i'm using mvc model...
the records are fetched by a model and returned to a servlet and that ResultSet is added to session as an attribute.. in the jsp file i try to retrieve that ResulSet :
ResultSet rs = (ResultSet)session.getAttribute("e_rs");
next i display those records
while(rs.next()) {
i get an exception in while(rs.next()) the exception information is below....
javax.servlet.ServletException: Operation not allowed after ResultSet closed
     org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:843)
     org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:776)
     org.apache.jsp.transactions_jsp._jspService(transactions_jsp.java:167)
     org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
     org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:334)
     org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
     org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
     com.example.web.order_history.doGet(order_history.java:29)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

The error message is :
Operation not allowed after ResultSet closed
which means that the code in the JSP page is trying to access a ResultSet object which has already been closed.
Instead of accessing the ResultSet in the JSP page I strongly encourage you to store the ResultSet in an ArrayList of a particular JavaBean object and then access that ArrayList in the JSP page.
You will be populating the ArrayList of JavaBean objects, in the same loop that you use to iterate over the ResultSet inside the JDBC layer while accessing individual records from the result set.
Make use of jsp:useBean tag to access the ArrayList in the JSP, and then use JSTL c:forEach tag to iterate over the resultset. JSTL 1.1 is the new way of writing JSP compared to scriptlets which make the code messy and complicated in JSPs.
Especially if you are using MVC which strongly discourages database or business logic directly in JSP pages.

Java Identifer Expected Error

Hi - I'm getting an error saying that an identifier is expected for the line d.addShare(s1);
I don't see why I need an identifier here - I've looked in all the classes to see if its linked to them but I can't find anything wrong. Maybe it will be clear to you- I've copied and pasted all my classes here (they are not very big). Been trying to debug this for ages but to no avail.
class Population {
Database d = new Database();
Random rand = new Random();
ArrayList population = new ArrayList();
ArrayList parents = new ArrayList();
ArrayList contenders = new ArrayList();
double[] reuters = {
8.0, 9.0, 12.5, 11.5, 6, 7, 4, 2, 3, 4, 3, 5, 5.5};
Share s1 = new Share(reuters);
d.addShare(s1); // Error: Identifier expected
public void initialPopulation() {
for (int i = 0; i < 10; i++) {
Chromosome c = new Chromosome(rand);
c.setDatabase(d);
population.add(c);
System.out.println("Chromosome Weights are: " + c);
System.out.println("Chromosome Fitness Value is: " + c.fitness(0));
//System.out.println();
System.out.println(population.size());
System.out.println(population.toString());
System.out.println();
System.out.println(d);
public ArrayList selectParents(int tournamentSize) {
// Get as many chromosomes as specified by tournament size
for (int i = 0; i < (tournamentSize); i++) {
contenders.add(i, population.get(i));
// Sort the sub-population in order of fitness
// contenders.sort;
// Return the best two
parents.add(contenders.get(0));
parents.add(contenders.get(1));
//System.out.println(parents.toString());
//System.out.println(contenders.toString());
return parents;
public static void main(String args[]) {
Population p = new Population();
p.initialPopulation();
p.selectParents(5);
import java.util.ArrayList;
class Database
{ ArrayList sharedata = new ArrayList();
public void addShare(Share s)
{ sharedata.add(s); }
public Share getShare(int i)
{ return (Share) sharedata.get(i); }
import java.util.ArrayList;
import java.util.Random;
class Chromosome
{ int[] bit = new int[12];
Database db;
Chromosome(Random rand)
{ for (int i = 0; i < 12; i++)
{ bit[i] = rand.nextInt(6); }
public String toString()
{ String res = "";
for (int i = 0; i < 12; i++)
{ res = res + bit[i] + ","; }
return res;
public void setDatabase(Database d)
{ db = d; }
public double fitness(int share)
{ double prediction = 0;
int divisor = 0;
Share sh = db.getShare(share);
for (int i = 0; i < 12; i++)
{ prediction = prediction + bit[i]*sh.getPrice(i);
divisor = divisor + bit;
if (divisor != 0)
{ prediction = prediction/divisor; }
else
{ prediction = 0; }
System.out.println("Prediction Value is: " + prediction);
double actualPrice = sh.getPrice(12);
return Math.abs(prediction - actualPrice);
class Share
{ double[] prices = new double[13];
Share(double[] p)
{ prices = p; }
double getPrice(int i)
{ return prices[i]; }
Thanks

Thanks for that - I'm now stuck on how exactly to define the selectParent() method because I have to take out samples of size 5 (the tournament size) from the population and then order those chromosomes ( in the contenders ArrayList) in order of fitness (the lower the fitness the better). But since I'm working with ArrayLists and since I have to extract each Chromosome object from the contender Arraylist, somehow call the fitness() method on each Chromosome, and then sort in order of fitness (lowest first), I'm kind of lost with how to do this. Any ideas on this? What's the simplest way of doing it? Thanks

Populating an ArrayList of ArrayList

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