Java program that counts words in a file

Question:

Write a java program that counts words in a file?

Answer:

Here is an example that counts the words in a file called TheCatInTheHat.txt.

Code:

import java.io.*;
import java.util.*;
 
public class WordCount {
  public static void main(String[] args) throws FileNotFoundException {
    Map<String, Integer> map = new HashMap<String, Integer>();
 
    Scanner in = new Scanner(new File("TheCatInTheHat.txt"));
    while (in.hasNext()) {
      String word = in.next();
      word = word.replaceAll("[^a-zA-Z0-9]", "");
      word = word.toLowerCase();
 
      if(map.containsKey(word)) {
        Integer count = (Integer)map.get(word);
        map.put(word, new Integer(count.intValue() + 1));
      } else {
        map.put(word, new Integer(1));
      }
    }
 
    ArrayList arraylist = new ArrayList(map.keySet());
    Collections.sort(arraylist);
 
    for (int i = 0; i < arraylist.size(); i++) {
      String key = (String)arraylist.get(i);
      Integer count = (Integer)map.get(key);
      System.out.println(key + " : " + count);
    }
 
  }
}

Output:

$ java WordCount
a : 33
about : 3
after : 1
all : 15
always : 1
and : 69
another : 2
any : 1
are : 5
as : 9
asked : 1
at : 14
away : 6
back : 2
bad : 2
ball : 5
be : 7
bed : 1
bent : 1
bet : 2
big : 5
bit : 3
bite : 1
.......