Creating a Java Program to Search a File for a Specific Word

Question

I am just learning that language and was wondering what a more experience Java programmer would do in the following situation?

I would like to create a java program

Answer 1

As others have pointed out, you could use the Scanner class.

I put your question in a file, data.txt, and ran the following program:

import java.io.*;
import java.util.Scanner;
import java.util.regex.MatchResult;

public class Test {
    public static void main(String[] args) throws FileNotFoundException {
        Scanner s = new Scanner(new File("data.txt"));
        while (null != s.findWithinHorizon("(?i)\\bjava\\b", 0)) {
            MatchResult mr = s.match();
            System.out.printf("Word found: %s at index %d to %d.%n", mr.group(),
                    mr.start(), mr.end());
        }
        s.close();
    }
}

The output is:

Word found: Java at index 74 to 78.
Word found: java at index 153 to 157.
Word found: Java at index 279 to 283.

The pattern searched for, (?i)\bjava\b, means the following:

• (?i) turn on the case-insensitive switch
• \b means a word boundry
• java is the string searched for
• \b a word boundry again.

If the search term comes from the user, or if it for some other reason may contain special characters, I suggest you use \Q and \E around the string, as it quotes all characters in between, (and if you're really picky, make sure the input doesn't contain \E itself).