Word count program in Java

Question

I am trying to write clean code in Java for reading text of any size and printing the word count in ascending order without using Java collection framework.

For example, given the following input text "What is the your name of the name?", it should print:

your 1
of 1
is 1
What 1
name 2
the 2

I have written the below code, but I am not sure it is the right answer. Please evaluate it.

public class WordArrayList {
private WordData[] words;
public void setWords(WordData[] words) {
this.words = words;
}
public WordData[] getWords() {
return words;
}
private int size;
public WordData getWord(int index) {
 return words[index];
 }
 public int getSize() {
 return size;
 }
 private static final int DEFAULT_WORD_ARRAY_SIZE = 10; 
 private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
 public WordArrayList() {
 words = new WordData[DEFAULT_WORD_ARRAY_SIZE];
 }
 public WordArrayList(int initialCapacity) {
 super();
 if (initialCapacity < 0)
 throw new IllegalArgumentException("Illegal Capacity: "
 + initialCapacity);
 words = new WordData[initialCapacity];
 }
 public int insertWord(final String word) {
 if (checkAndAddExistingWord(word)) {
 return 0;
 }
 checkAndIncreaseCapacity();
 words[size] = new WordData(word);
 size++;
 return 1;
 }
 private boolean checkAndAddExistingWord(String word) {
 int position = 0;
 for (position = 0; position < size; position++) {
 if (words[position].getWord().equals(word)) {
 words[position].incrementWordCount();
 return true;
 }
 }
 return false;
 }
 private void checkAndIncreaseCapacity() {
 if (isWordArrayFull(size))
 increaseCapacity(size);
 }
 private void increaseCapacity(int size) {
 int newCapacity = size * 2;
 if (newCapacity > MAX_ARRAY_SIZE) {
 newCapacity = Integer.MAX_VALUE;
 }
 WordData[] newWords = new WordData[newCapacity];
 System.arraycopy(words, 0, newWords, 0, size);
 }
 private boolean isWordArrayFull(int wordCount) {
 return (wordCount - words.length > 0);
 }
 public void setWord(int i, WordData word) {
 words[i] = word;
 }
public class TextAnalyzer {
 private static final String REG_SPLIT_EXP = "\\s+";
 private String text;
 private String textSplitExp;
 private WordArrayList wordArrayList;
 public TextAnalyzer(String text, String textSplitExp) {
 this.textSplitExp = textSplitExp;
 this.text = text;
 wordArrayList = new WordArrayList();
 }
 public TextAnalyzer(String text) {
 this.textSplitExp = REG_SPLIT_EXP;
 this.text = text;
 wordArrayList = new WordArrayList();
 }
 private String[] convertToArray() {
 return text.split(textSplitExp);
 }
 public void generateWordArrayList() {
 String[] splitTextArray = convertToArray();
 for (int i = 0; i < splitTextArray.length; i++) {
 wordArrayList.insertWord(splitTextArray[i]);
 }
 }
 public void printWordArrayList() {
 for (int i = 0; i < wordArrayList.getSize(); i++) {
 System.out.println("=" + wordArrayList.getWord(i).getWord() + "=="
 + wordArrayList.getWord(i).getWordCount());
 }
 }
 public void sortWordArrayList() {
 TextAnalyzerUtil.sort(wordArrayList);
 }
}
public class WordData {
 public WordData(final String vWord) {
 this.word = vWord;
 this.wordCount=1;
 }
 private String word;
 public int getWordCount() {
 return wordCount;
 }
 public void setWordCount(int wordCount) {
 this.wordCount = wordCount;
 }
 public void setWord(String word) {
 this.word = word;
 }
 private int wordCount;
 private int position;
 public String getWord() {
 return word;
 }
 public void incrementWordCount() {
 this.wordCount++;
 }
 public int getPosition() {
 return position;
 }
 public void setPosition(int position) {
 this.position = position;
 }
}

For testing:

analyzer.generateWordArrayList();
 analyzer.sortWordArrayList();
 analyzer.printWordArrayList();

• Simon Forsberg: Could you include the TextAnalyzerUtil.sort method in your code? That way we could compile the code ourselves and therefore make a better review.
• Simon Forsberg: Nevermind, sorting the word list isn't that important really :)

Answer 1

There are a couple of things you should think about or fix:

• Indentation. You're not really consistent in indenting your code. Please follow the Java conventions.

• No need to call super() inside your constructor, the default empty super constructor is automatically called.

• Use "constructor chaining" in WordArrayList, and TextAnalyzer. That is, call one constructor from another. For example,

  public TextAnalyzer(String text) {
   this(text, REG_SPLIT_EXP);
  }
  

• You have a whole lot of unnecessary methods: setWords, getWords, setWordCount, setWord. You don't use them and I really don't think that you need them.

• Use private final for fields that should be initialized once and then never change, such as private final String word; in the WordData class. Apply this wherever possible.

• private int position; is not used in WordData, and I don't think you need to use it either. Select and press the Delete button on your keyboard

• I suggest naming the class WordList instead. The fact that it uses an array is not important. It is a List of words, how the internal list works is not needed for the user to know

• Calling generateWordArrayList multiple times would produce strange results.

• convertToArray is private, contains one line, and is only called from one location: Does it really need to be it's own method?

• Use a "for-each" loop to improve readability when iterating:

  for (String str : splitTextArray)
  

• You can store the number of times each word occurs with a HashMap<String, Integer> instead. To initialize the HashMap, you can use this:

  Map<String, Integer> words = new HashMap<String, Integer>();
  for (String str : splitTextArray) {
   if (words.containsKey(str))
   words.put(str, words.get(str) + 1);
   else words.put(str, 1);
  }
  

  Note that you can use TreeMap instead of HashMap to keep the keys in a sorted order, so that if you iterate over words.entrySet(), you will always iterate in sorted order. (You can also provide a custom Comparator to the TreeMap if you are not satisfied with the built-in sorting)

Overall the current classes you have seems to do what they are supposed to do, and the result is correct. Good job.

• Nitin: thanks for your prompt response sorry for not adding sorting code but it was just quick sort. Can the above code be done in better way. I am asking in better design prospect.
• Simon Forsberg: @Nitin Remove the WordData class, and replace the WordArrayList class with a Map<String, Integer>. That's the simplest and in my opinion best way to get the job done.
• Nitin: Hi Simon, sorry i need to write code without collection so no hashmap
• Simon Forsberg: @Nitin In that case, just clean up your code by following the other points I have pointed out for you.
• bowmore: When putting a count as a value in a map, I tend to use a mutable value (e.g. AtomicInteger) so updating the count can be done without doing a put every time.

Answer 2

Bug

In increaseCapacity(), you create a new array and copy the old contents to it, but never replace the old array.

Efficiency

The running time will be O(n²), where n is the number of words, since you could potentially run through the entire existing array when adding a new word. Using a HashMap would be O(n), and a TreeMap would be O(n log n). You are probably doing this the "hard" way for fun, so that's OK, as long as you are aware of the potential performance problem.

Interface

You should pare down the number of exposed methods, not just to reduce the amount of code, but to improve the interface. If you put getters and setters on all fields, your class would be too promiscuous. At that point, you might as well make all the fields public. (In fact, the way your current code exposes all its state, it is about as unmaintainable as code that uses global variables.) By choosing what methods to expose, you give the class a specific purpose and prevent it from being misused. Also, limiting the interface helps you reserve the capability to change the implementation, should you come up with a better idea later.

For WordArrayList:

• You should rename it to WordCounter. WordArrayList sounds like a generic, passive data structure. WordCounter has a clear purpose.
• insertWord() is a misnomer, it implies that it will always result in an additional entry, and that the caller has some control over the order of insertion. I think addWord() would be more appropriate.
• I would also offer addWords(String[] words), since it's convenient for callers, and it might present opportunities for optimization if you add a whole batch of words at once.
• Instead of exposing the guts of the object, I suggest presenting a method to retrieve an Enumeration of the results, based on the general advice above. (When the Java Collections Framework was introduced in 1.2, Enumeration was semi-deprecated in favor of Iterator. I don't know if you consider Iterator to be off-limits as a result, so I chose the antiquated Enumeration interface instead.)
• I would consolidate your private helper methods a bit for simplicity.
• I've added a reset() method to clear all the counts, which is quite optional. It makes up for the removal of WordCount.setWordCount().

For WordData:

• I would expose just getWord() and getWordCount() (probably better renamed to getCount()).
• The position should not be stored part of WordData, and in fact you never use it.
• You made the constructor take a final argument. That's OK, but the better place to put the final keyword is in the private final String word declaration.
• I choose to make it an inner class of WordCounter, but that's just my preference.

Note that with these changes, users of WordCounter have no way to muck with its internal state except through the approved interfaces. WordCounter can offer some guarantees of self consistency in a way that the original WordArrayList couldn't. If it's used in a more complex system, those guarantees make it possible for you to debug the code using reasoning.

Constructor chaining

Whenever you offer more than one constructor, you should chain them, such that the one with more default parameters calls the one with explicit parameters.

Code formatting

Your code formatting is all over the place, in terms of indentation. You should also leave a blank line between methods for readability.

import java.util.Arrays;
import java.util.Comparator;
import java.util.Enumeration;
import java.util.NoSuchElementException;
public class WordCounter {
 //////////////////////////////////////////////////////////////////////
 public static class WordData {
 private final String word;
 private int wordCount;
 WordData(String vWord) {
 this.word = vWord;
 this.wordCount = 1;
 }
 public String getWord() {
 return word;
 }
 public int getWordCount() {
 return wordCount;
 }
 }
 //////////////////////////////////////////////////////////////////////
 private static class WordFrequencyComparator implements Comparator<WordData> {
 @Override
 public int compare(WordData a, WordData b) {
 int wcDiff = b.getWordCount() - a.getWordCount();
 return wcDiff != 0 ? wcDiff : a.getWord().compareTo(b.getWord());
 }
 }
 //////////////////////////////////////////////////////////////////////
 private WordData[] words;
 private int size;
 private static final int DEFAULT_WORD_ARRAY_SIZE = 10;
 private static final Comparator<WordData> DESCENDING_WORD_FREQUENCY_COMPARATOR = new WordFrequencyComparator();
 public WordCounter() {
 this(DEFAULT_WORD_ARRAY_SIZE);
 }
 public WordCounter(int initialCapacity) {
 if (initialCapacity < 0)
 throw new IllegalArgumentException("Illegal Capacity: "
 + initialCapacity);
 words = new WordData[initialCapacity];
 }
 /**
 * Clears the word count.
 */
 public void reset() {
 for (int i = 0; i < size; i++) {
 words[i] = null;
 }
 }
 /**
 * Adds word to the word count.
 *
 * @return 1 if the word was previously unseen, 0 otherwise.
 */
 public int addWord(String word) {
 checkAndIncreaseCapacity(size + 1);
 if (checkAndAddExistingWord(word)) {
 return 0;
 }
 words[size++] = new WordData(word);
 return 1;
 }
 /**
 * Adds words to the word count.
 *
 * @return the number of previously unseen words.
 */
 public int addWords(String[] words) {
 checkAndIncreaseCapacity(size + words.length);
 int newWordsAdded = 0;
 for (String w : words) {
 newWordsAdded += addWord(w);
 }
 return newWordsAdded;
 }
 /**
 * Returns an Enumeration of the WordData in descending order of word
 * frequency. Behavior is undefined if you add words or reset the
 * counter while enumerating.
 */
 public Enumeration<WordData> elements() {
 Arrays.sort(words, 0, size, DESCENDING_WORD_FREQUENCY_COMPARATOR);
 return new Enumeration<WordData>() {
 private int i = 0;
 @Override
 public boolean hasMoreElements() {
 return i < size;
 }
 @Override
 public WordData nextElement() {
 try {
 return words[i++];
 } catch (ArrayIndexOutOfBoundsException e) {
 throw new NoSuchElementException();
 }
 }
 };
 }
 private boolean checkAndAddExistingWord(String word) {
 for (WordData wd : words) {
 if (wd.getWord().equals(word)) {
 wd.wordCount++;
 return true;
 }
 }
 return false;
 }
 private void checkAndIncreaseCapacity(int sizeHint) {
 if (size >= words.length) {
 int newCapacity = size * 2;
 if (newCapacity < sizeHint) {
 newCapacity = sizeHint;
 }
 if (newCapacity < 0) {
 newCapacity = Integer.MAX_VALUE;
 }
 WordData[] newWords = new WordData[newCapacity];
 System.arraycopy(words, 0, newWords, 0, size);
 words = newWords;
 }
 }
}

With the changes above, TextAnalyzer can become a lot simpler:

import java.util.Enumeration;
public class TextAnalyzer {
 private static final String REG_SPLIT_EXP = "\\s+";
 private WordCounter wordCounter;
 public TextAnalyzer(String text, String textSplitExp) {
 wordCounter = new WordCounter();
 wordCounter.addWords(text.split(textSplitExp));
 }
 public TextAnalyzer(String text) {
 this(text, REG_SPLIT_EXP);
 }
 public void printWords() {
 Enumeration<WordCounter.WordData> words = wordCounter.elements();
 while (words.hasMoreElements()) {
 WordCounter.WordData wordData = words.nextElement();
 System.out.println("=" + wordData.getWord() + "=="
 + wordData.getWordCount());
 }
 }
}

• Nitin: thanks @200_success. I have couple of doubts 1. Can we scale this application for large number of text e.g. 1 miilion words. 2. Arrays is part of collection framework and use legacy sort which in terns clone the whole can we use sort without using Arrays?.
• 200_success: 1. See my remarks about efficiency in the review. 2. You're right on both counts. Arrays was introduced with Java Collections in Java 1.2, and Arrays.sort(Object[]) uses mergesort, which does not operate in place. In place of Arrays.sort(), you could substitute whatever sorting method you were using before.