// File: WordCounter.java
// Program from Section 5.7 to illustrate the use of TreeMaps and Iterators.
// The program opens and reads a file called words.txt. Each line in this
// file should consist of one or more English words separated by spaces.
// The end of each line must not have any extra spaces after the last word.
// The program reads the file and then a table is printed of
// all words and their counts.

import java.util.*;  // Provides TreeMap, Iterator, Scanner
import java.io.*;    // Provides FileReader, FileNotFoundException

public class WordCounter
{
   public static void main(String[ ] args)  
   {   
      TreeMap<String, Integer> frequencyData = new TreeMap<String, Integer>( );

      readWordFile(frequencyData); 
      printAllCounts(frequencyData);
   }

   public static int getCount
   (String word, TreeMap<String, Integer> frequencyData)
   {
      if (frequencyData.containsKey(word))
      {  // The word has occurred before, so get its count from the map
	   return frequencyData.get(word); // Auto-unboxed
      }
      else
      {  // No occurrences of this word
         return 0;
      }
   }

   public static void printAllCounts(TreeMap<String, Integer> frequencyData)
   {
      System.out.println("-----------------------------------------------");
      System.out.println("    Occurrences    Word");

      for(String word : frequencyData.keySet( ))
      {
         System.out.printf("%15d    %s\n", frequencyData.get(word), word);
      }

      System.out.println("-----------------------------------------------");
   }  

   public static void readWordFile(TreeMap<String, Integer> frequencyData)
   {
      Scanner wordFile;
      String word;     // A word read from the file
      Integer count;   // The number of occurrences of the word

      try
      {
         wordFile = new Scanner(new FileReader("words.txt"));
      }
      catch (FileNotFoundException e)
      {
	 System.err.println(e);
	 return;
      }
      
      while (wordFile.hasNext( ))
      {
          // Read the next word and get rid of the end-of-line marker if needed:
	  word = wordFile.next( );

          // Get the current count of this word, add one, and then store the new count:
          count = getCount(word, frequencyData) + 1;
          frequencyData.put(word, count);
      }
   } 

}