1  import java.util.Map;

  2  import java.util.Scanner;

  3  import java.util.TreeMap;

  4  import java.io.File;

  5  import java.io.FileNotFoundException;

  6  

  7  /**

  8     This program prints the frequencies of all words in "Alice in Wonderland".

  9  */

 10  public class WordFrequency

 11  {

 12     public static void main(String[] args) 

 13        throws FileNotFoundException

 14     {

 15        Map<String, Integer> frequencies = new TreeMap<String, Integer>();

 16        Scanner in = new Scanner(new File("alice30.txt"));

 17        while (in.hasNext())

 18        {

 19           String word = clean(in.next());    

 20  

 21           // Get the old frequency count

 22  

 23           Integer count = frequencies.get(word);

 24  

 25           // If there was none, put 1; otherwise, increment the count

 26  

 27           if (count == null) { count = 1; }

 28           else { count = count + 1; }        

 29  

 30           frequencies.put(word, count);

 31        }

 32  

 33        // Print all words and counts

 34  

 35        for (String key : frequencies.keySet())

 36        {

 37           System.out.printf("%-20s%10d\n", key, frequencies.get(key));

 38        }

 39     }

 40  

 41     /**

 42        Removes characters from a string that are not letters.

 43        @param s a string

 44        @return a string with all the letters from s

 45     */

 46     public static String clean(String s)

 47     {

 48        String r = "";

 49        for (int i = 0; i < s.length(); i++)

 50        {

 51           char c = s.charAt(i);

 52           if (Character.isLetter(c))

 53           {

 54              r = r + c;

 55           }

 56        }

 57        return r.toLowerCase();

 58     }

 59  }