// This program counts the number of unique words in a large file.
// This program calculates the number of unique words in a file 
// and prints out information about how long it took to run
s
import java.io.*;
import java.util.*;

public class UniqueWords {
    public static void main(String[] args) throws FileNotFoundException {
        System.out.println("Reading file...");
        Scanner input = new Scanner(new File("mobydick.txt"));
        
        long start = System.currentTimeMillis();
        
        int uniqueWords = countUnique(input);
        
        long end = System.currentTimeMillis();
        long elapsed = end - start;
        
        System.out.println("The file has " + uniqueWords + " words.");
        System.out.println("Took " + elapsed + " ms.");
    }
    
    // pre: input is not null
    // post: returns the number of unique tokens in input
    public static int countUnique(Scanner input) {
        // List<String> words = new ArrayList<String>();
        // Set<String> words = new Treeset<String>();
        Set<String> words = new HashSet<String>();
        while (input.hasNext()) {
            String word = input.next();
            
            if (!words.contains(word)) {
                words.add(word);
            }
        }
        return words.size();
    }    
    
    
    // pre: words is not null
    // post: prints the words in the given list that have even length.
    private static void printEvenLengthWords(List<String> words) {
        // Hunter: Changed the parameter to type List so I am always using the interface type
        
        // Confusing differences in how to get how many elements are contained
        // arrays => length
        // Strings => length()
        // ArrayList => size()
        
        /* Hunter: for loop, only works for things with indices (lists, arrays)
         * for (int i = 0; i < words.size(); i++) {  
         *     String word = words.get(i);
         *   
         *     if (word.length() % 2 ==0 ){
         *         System.out.println(word);
         *     }
         * }
         */ 
        
        /* Hunter: foreach loop, works for pretty much all collections (including arrays)
         * Note: only works for read-only operations, can't remove
         */
        for (String word : words) {
            if (word.length() % 2 ==0 ){
                // words.remove(word); Causes a ConcurrentModificationException
                System.out.println(word);
            }  
        }
        
        /* Hunter: iterator, works for pretty much all collections (excluding arrays)
         * Iterator interface
         *     hasNext(), returns true if there are more elements to return
         *     next(), returns the next thing in the list (advances the iterator forward)
         *     remove(), removes the last thing returned by a call to next()
         *
         * Iterator<String> itr = words.iterator();
         * while (itr.hasNext()) {
         *     String word = itr.next();
         *     if (word.length() % 2 ==0 ){
         *         itr.remove();
         *         // words.remove(word); Causes a ConcurrentModificationException
         *         System.out.println(word);
         *     } 
         * }
         */
    }
}