Assignment please!

Question

Could someone please give me some assignment for learning Collections and/or IO?
TIA
UW

Answer 1

Write a program that can list the 25 most common
words found in
a given text file and their number of occurrences.
import java.io.BufferedReader;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.StringTokenizer;
import java.io.IOException;
  * Assignment class for counting the occurences of each word in the text
  * and display the words in sorted order of most common occurences.
  * The program excludes the words present in the exclusion file.
  * Suggested by DrLaszloJamf
  * Coded by Undead Wraith :-)
public class UndeadAssignment1 {
    public static void main(String[] args) {
        System.out.println("Start assignment... :-)");
        // File containing words to be excluded.
        String excludeFile  = "exclude.list";
        // File containing the text
        String textFile     = "foo.in";
        try {
            Set excludeSet  = loadExclusionSet(excludeFile);
            Map countMap    = readFileCount(textFile, excludeSet);
            List resultList = sortMapResults(countMap);
            printResults(resultList);
        } catch (UndeadException ue) {
            System.out.println("Back to the crypt... :-(");
            ue.printStackTrace();
        System.out.println("End assignment...");
    // Reads the file and counts the words in it, omitting the excluded word set.
    public static Map readFileCount(String textFile, Set excludeSet) throws UndeadException {
        Map hm                  = new HashMap();
        BufferedReader br       = null;
        String input            = null;
        String result           = null;
        StringTokenizer strTok  = null;
        int integer             = 0;        // Temporary initialization.
        try {
            br = new BufferedReader(new FileReader(textFile));
            while((input = br.readLine()) != null) {
                strTok = new StringTokenizer(input);
                while(strTok.hasMoreTokens()) {
                    result = strTok.nextToken().replaceAll("[,.;:?!@#$%^&*()\\[\\]{}<>\\/-]", "").toLowerCase();
                    if(!result.trim().equals("") && !excludeSet.contains(result)) {
                        if(hm.containsKey(result)) {
                            integer = ((Integer)hm.get(result)).intValue();
                            integer++;
                            hm.put(result, new Integer(integer));
                        } else {
                            hm.put(result, new Integer("1"));
        } catch (IOException ioe) {
            throw new UndeadException(ioe.getMessage());
        } catch(Exception e) {
            throw new UndeadException(e.getMessage());
        return hm;
    // Reads the excluded word set.
    public static Set loadExclusionSet(String excludeFile) throws UndeadException {
        Set exclusionSet   = new HashSet();
        BufferedReader br  = null;
        String input       = null;
        try {
            br = new BufferedReader(new FileReader(excludeFile));
            while((input = br.readLine()) != null) {
                exclusionSet.add(input.trim());
        } catch (IOException ioe) {
            throw new UndeadException(ioe.getMessage());
        } catch(Exception e) {
            throw new UndeadException(e.getMessage());
        return exclusionSet;
    // Prints the result.
    // This would be modified to output to an Excel workbook.
    public static void printResults(List list) {
        String str         = null;
        Iterator iterator  = list.iterator();
        System.out.println("Results: ");
        while(iterator.hasNext()) {
            str = (String)iterator.next();
            System.out.println(str);
    // Sort the results in the Map and returns a List in requisite format.
    public static List sortMapResults(Map resultMap) throws UndeadException {
        Set printSet       = resultMap.entrySet();
        List resultList    = new ArrayList();
        Iterator iterator  = printSet.iterator();
        String tempString  = null;
        try {
            while(iterator.hasNext()) {
                resultList.add(iterator.next().toString());
            Collections.sort(resultList, new MyComparator());
        } catch (Exception e) {
            throw new UndeadException(e.getMessage());
        return resultList;
  * UndeadException class.
  * My own damn exception
  * to play around with exception handling.
class UndeadException extends Exception {
    UndeadException(String message) {
        super(message);
  * MyComparator class.
  * Compares two Strings - intended to sort
  * by name ascending and count descending.
class MyComparator implements Comparator {
    public int compare(Object o1, Object o2) {
        String s1 = o1.toString();
        String s2 = o2.toString();
        int i1 = Integer.parseInt(s1.toString().substring(s1.indexOf("=") +1));
        int i2 = Integer.parseInt(s2.toString().substring(s2.indexOf("=") +1));
        if(i1 == i2) {
            return s1.compareTo(s2);
        } else {
            return i2 - i1;
}Here's my code after a considerable effort to read the API all by myself. I hope someone finds some faults with this.
I'll try to add the Excel workbook thing now :)
Thanks all!
UW