Chapter 20, Problem 20.1PE

(Display words in ascending alphabetical order) Write a program that reads words from a text file and displays all the words (duplicates allowed) in ascending alphabetical order. The words must start with a letter. The text file is passed as a command-line argument.

Program Plan Intro

Display words in ascending alphabetical order

Program plan:

• Import the required packages into the program.
• In the main() method,
  • Check whether the argument length is not equal to 1. If yes,
    • Display the error message.
  • Assign the argument 0 as filename.
  • Create a list to hold the words.
  • In try block,
    • Check the matches between the word from file and alphabets.
    • Call the add() method to add the word into list.
  • Catch the exception if error occurs.
  • Call sort() method to sort the list in ascending order.
  • Display the ascending order word.

Program Description Answer

The below program demonstrates to sort the word in ascending order from the file and display that list.

Explanation of Solution

Program:

//Import the java packages

import java.util.*;

import java.io.*;

//Class definition

public class Exercise20_01

{

//Main method

public static void main(String[] args)

{

/*Check whether the argument length is not equal to 1 */

if (args.length != 1) {

//Display the error message

System.out.println("Usage: java Exercise20_01 fullfilename");

System.exit(1);

}

//Assign the argument 0 as filename

String filename = args[0];

// Create a list to hold the words

List<String> list = new ArrayList<>();

//In try block

try {

//Create an object for Scanner class

Scanner in = new Scanner(new File(filename));

//Loop executes until the input from file

while (in.hasNext()) {

//Declare and assign the string //variable

String word = in.next();

//Check matches among the word from //file

if (word.matches("[a-z|A-Z].*"))

/*Call add() method to add the word into list */

list.add(word);

}

}

//Catch the exception

catch (Exception ex) {

//Display the error message

System.err.println(ex);

}

/*Call sort() method to sort the list in ascending order */

Collections.sort(list);

// Display the result

System.out.println("Display words in ascending order ");

//Loop executes until the list

for (String word : list) {

//Display the ascending order word

System.out.println(word);

}

}

}

Sample Output

Input file:

Screenshot of Test.txt file

Command to run the program:

java Exercise20_01 Test.txt

Display words in ascending order

hello

hi

hi

jhon

mercy

welcome