JAVA EE: How to count the number of times the word dog appears in the input string using Java Regex

Tuesday 19 December 2017

How to count the number of times the word dog appears in the input string using Java Regex

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RegexDemo.java

import java.util.regex.Matcher;

import java.util.regex.Pattern;

/**
 * 
 * This example that counts the number of times the word "dog" appears in the
 * input string
 *
 */

public class RegexDemo

{

    private static final String REGEX = "\\bdog\\b";

    private static final String INPUT = "dog dog dog dogiee dog";

    public static void main(String[] args)

    {

        Pattern p = Pattern.compile(REGEX);

        Matcher m = p.matcher(INPUT); // get a matcher object

        int count = 0;

        /*
         * Returns:true if, and only if, a subsequence of the input sequence
         * matches this matcher's pattern
         */

        while (m.find())

        {

            count++;

            System.out.println("Match number " + count);

            /*
             * Returns the start index of the previous match.
             */

            System.out.println("start(): " + m.start());

            /*
             * Returns the offset after the last character matched.
             */

            System.out.println("end(): " + m.end());

            System.out.println("---------------------");

        }

    }

}

Output

Match number 1

start(): 0

end(): 3

---------------------

Match number 2

start(): 4

end(): 7

---------------------

Match number 3

start(): 8

end(): 11

---------------------

Match number 4

start(): 19

end(): 22

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