URGENT: Sorting a vector of object by an element

Hi,

I have been stuck on this part of my program for ages and I really need some help urgently as I need to submit my coursework. I need to create a comparator for the serialnumber of each questionnaire that is stored in a vector. Here is the coding:

import java.beans.XMLDecoder;
import java.beans.XMLEncoder;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Scanner;
import java.util.Vector;

class MainInput {
public static void main(String[] args) throws IOException {
Scanner scanner = new Scanner(System.in);

int numberofquestions = 0;
int rangeno;
int serialnumber;
int age;
int answer;
int actualquestionno;
int rangeforquestion;
char sex;
String option;
String postcode;
int[] allanswers;

Vector<QuestionnaireFields> loaded = null;
XMLDecoder decoder = null;
try {
decoder = new XMLDecoder(new BufferedInputStream(
new FileInputStream("QuestionnaireData.xml")));
loaded = (Vector<QuestionnaireFields>) decoder.readObject();
} catch (Exception e) {
loaded = new Vector<QuestionnaireFields>();
} finally {
if (decoder != null) {
decoder.close();
}
}

int[] fixedformat = CheckingStructureSetting.loading();

if (fixedformat == null) {

while (true) {
System.out.print("Enter number of questions: ");
numberofquestions = scanner.nextInt();

if (numberofquestions < 1 | numberofquestions > 10) {
System.out
.print("Invalid Range. Choose between 1 and 10: ");
} else {
break;
}

}

fixedformat = new int[numberofquestions];

for (int count = 0; count < numberofquestions; count++) {

while (true) {
System.out.print("Enter Range for Question " + (count + 1)+ (": "));
rangeno = scanner.nextInt();

if (rangeno < 2 | rangeno > 10) {
System.out
.println("Invalid Range. Choose between 2 and 10: ");
} else {
fixedformat[count] = rangeno;
break;
}

}
}

CheckingStructureSetting.storing(fixedformat);
}

allanswers = new int[fixedformat.length];

do {
QuestionnaireFields questionnaireobject = new QuestionnaireFields();

System.out.print("Questionnaire Number: ");
serialnumber = scanner.nextInt();
questionnaireobject.setSerialNumber(serialnumber);

System.out.print("Age: ");
age = scanner.nextInt();
questionnaireobject.setAge(age);

System.out.print("Sex <[M] for male, [F] for female>: ");
sex = scanner.next().charAt(0);
questionnaireobject.setSex(sex);

System.out.print("Postcode: ");
postcode = scanner.next();
questionnaireobject.setPostcode(postcode);

for (int count = 0; count < fixedformat.length; count++) {

while (true) {
System.out.print("Response to Question " + (count + 1) + ": ");
answer = scanner.nextInt();
if (answer < 1 | answer > fixedformat[count]) {
System.out
.print("Invalid answer! Out of range!! Please enter another answer: ");
} else {
allanswers[count] = answer;
break;
}
}
}

questionnaireobject.setAnswers(allanswers);

loaded.add(questionnaireobject);

System.out.print("Do you want to enter another questionnaire? [Y] Yes or [N] No: ");
option = scanner.next();

} while (!option.equalsIgnoreCase("N"));

XMLEncoder encoder = new XMLEncoder(new BufferedOutputStream(
new FileOutputStream("QuestionnaireData.xml")));
encoder.writeObject(loaded);
encoder.close();

}
}

I have another class to create each questionnaire

public class QuestionnaireFields{
private int serialnumber;
private char sex;
private int age;
private String postcode;
private int[] allanswers;

public void setSerialNumber(int serialnumber) {
this.serialnumber = serialnumber;
}

public int getSerialNumber() {
return serialnumber;
}

public void setSex(char sex) {
this.sex = sex;
}

public char getSex() {
return sex;
}

public void setAge(int age) {
this.age = age;
}

public int getAge() {
return age;
}

public void setPostcode(String postcode) {
this.postcode = postcode;
}

public String getPostcode() {
return postcode;
}

public void setAnswers(int[] settinganswers) {
this.allanswers = settinganswers;
}

public int[] getAnswers() {
return allanswers;
}


}

Any help is very much appreciated but please give me an answer how I can use the comparator for a vector of objects now as I need to submit the coursework tomorrow: ie: no time to search!! Aargghh!!

Code:

---

import java.util.*;

public class ComparatorTest {
    public static void main(String[] args) {
        Vector<DataStore> v = new Vector<DataStore>();
        populateVector(v);
        print(v, "Unsorted:");
        Collections.sort(v, numberComparator);
        print(v, "Sorted:");
    }

    private static void populateVector(Vector<DataStore> v) {
        Random seed = new Random();
        v.add(new DataStore("Sean", "Dunston ", seed.nextInt(100)));
        v.add(new DataStore("Vera", "Hastings", seed.nextInt(100)));
        v.add(new DataStore("Mary", "Bangor  ", seed.nextInt(100)));
        v.add(new DataStore("Eric", "Norwich ", seed.nextInt(100)));
    }

    private static void print(Vector<DataStore> v, String s) {
        System.out.println(s);
        for(DataStore store : v) {
            System.out.println(store);
        }
        System.out.println("-------------------");
    }

    //  javac -Xlint:unchecked comparatortest.java
    private static Comparator<DataStore> numberComparator =
                        new Comparator<DataStore>() {
        public int compare(DataStore ds1, DataStore ds2) {
            int sn1 = ds1.serialNumber;
            int sn2 = ds2.serialNumber;
            return (sn1 < sn2) ? -1 : (sn1 > sn2) ? 1 : 0;           
        }
    };
}

class DataStore {
    String name;
    String city;
    int serialNumber;

    DataStore(String name, String city, int sn) {
        this.name = name;
        this.city = city;
        serialNumber = sn;
    }

    public String toString() {
        return getClass().getName() +
              "[name:" + name +
              " city:" + city +
              " serialNumber:" + serialNumber + "]";
    }
}

---