// This program calculates the number of times each word appears in a file
import java.io.*;
import java.util.*;

public class WordCounter {
   public static void main(String[] args) throws FileNotFoundException {
      System.out.println("Reading file...");
      Scanner input = new Scanner(new File("mobydick.txt"));
      
      Map<String, Integer> wordCounts = countWords(input);
      
      for (String word : wordCounts.keySet()) {
         System.out.println(word + " " + wordCounts.get(word));
      }
   }

   // post: returns a Map where the keys are the unique words in the input file
   // and the values are the number of times that word appeared in the file
   public static Map<String, Integer> countWords(Scanner input) {
      Map<String, Integer> wordCounts = new TreeMap<>();
      while (input.hasNext()) {
         String word = input.next();
         
         // Two cases:
         // 1. the first time we see a key
         // 2. we've seen this key before
         if (!wordCounts.containsKey(word)) {
            wordCounts.put(word, 1);
         } else {
            wordCounts.put(word, wordCounts.get(word) + 1);
            /*
            // Can also write it this two line way
            int oldCount = wordCounts.get(word);
            wordCounts.put(word, oldCount + 1);
            */
         }
         
         /*
         // Another way to write the code above
         // One case for the first time we see the word, and
         // a general case we run every time
         if (!wordCounts.contains(word)) {
            wordCounts.put(word, 0);
         }
         wordCounts.put(word, wordCounts.get(word) + 1);
         */
      }
      
      return wordCounts;
   }
  
}