Chapter 11, Problem 20E

Explanation of Solution

Modified class “Vocabulary” that uses “Set” instead of “ArrayList”:

//Import required packages

import java.util.*;

import java.io.*;

//Definition of class Vocabulary

public class Vocabulary {

    //Definition of main method

    public static void main(String[] args)

    throws FileNotFoundException

    {

        //Create an object for scanner class

        Scanner sc = new Scanner(System.in);

        //Call the method printIntro()

        printIntro();

        //Get the first file name

        System.out.print("file #1 name? ");

        String filename1 = sc.nextLine();

        //Create an object for scanner class

Scanner file1 = new Scanner(new File(filename1));

        //Get the second file

        System.out.print("file #2 name? ");

        String filename2 = sc.nextLine();

        //Create an object for scanner class

Scanner file2 = new Scanner(new File(filename2));

        System.out.println();

        //Create an object for set

        Set<String> set1 = getWordsFromFile(file1);

        Set<String> set2 = getWordsFromFile(file2);

        Set<String> overlap = new TreeSet(set1);

        //Call the method retainAll

        overlap.retainAll(set2);

        //Call the method Result

        Result(set1, set2, overlap);

    }

    //Definition of method getWordsFromFile

public static Set<String> getWordsFromFile(Scanner input) {

    //Create an object for set

    Set<String> result = new TreeSet<String>();

    // read all words from the file

    while (input.hasNext()) {

        //Get the values and store it in val

        String val = input.next().toLowerCase();

        //Add the value to the result

        result...