package regex;

import java.util.*;

import java.util.regex.*;

/**

This program tests regular expression matching. Enter a pattern and strings to match,

or hit Cancel to exit. If the pattern contains groups, the group boundaries are displayed

in the match.

@version 1.02 2012-06-02

@author Cay Horstmann

*/

public class RegexTest

{

public static void main(String[] args) throws PatternSyntaxException

{

Scanner in = new Scanner(System.in);

System.out.println("Enter pattern: ");

String patternString = in.nextLine();

Pattern pattern = Pattern.compile(patternString);

while (true)

{

System.out.println("Enter string to match: ");

String input = in.nextLine();

if (input == null || input.equals("")) return;

Matcher matcher = pattern.matcher(input);

if (matcher.matches())

{

System.out.println("Match");

int g = matcher.groupCount();

if (g > 0)

{

for (int i = 0; i < input.length(); i++)

{

// Print any empty groups

for (int j = 1; j <= g; j++)

if (i == matcher.start(j) && i == matcher.end(j))

System.out.print("()");

// Print ( for non-empty groups starting here

for (int j = 1; j <= g; j++)

if (i == matcher.start(j) && i != matcher.end(j))

System.out.print('(');

System.out.print(input.charAt(i));

// Print ) for non-empty groups ending here

for (int j = 1; j <= g; j++)

if (i + 1 != matcher.start(j) && i + 1 == matcher.end(j))

System.out.print(')');

}

System.out.println();

}

}

else

System.out.println("No match");

}

}

}