CountUniqueWords.java

import java.io.File;
import java.io.FileNotFoundException;
import java.util.*;
/*
arrays
lists
maps (or dictionaries)
sets
 */

public class CountUniqueWords {
    private static final String BOOK_FILENAME = "data/alice.txt";

    public static void main(String[] args) throws FileNotFoundException {
        //ArrayList<String> ds = new ArrayList<>();
        HashSet<String> ds = new HashSet<>();
        //HashMap!
        Scanner s = new Scanner(new File(BOOK_FILENAME));
        while (s.hasNext()) {
            String next = s.next();
            //if (!ds.contains(next)) {
                ds.add(next);
            //}
        }
        System.out.println(ds.size());
    }
}