Tuesday 19 December 2017

What are Java Regular Expressions and how to use pattern class | Java Regex | Regex in java


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What are Java Regular Expressions and how to use pattern class | Java Regex | Regex in java

What are Java Regular Expressions and how to use pattern class | Java Regex | Regex in java

RegexDemo1.java

import java.util.regex.Pattern;

public class RegexDemo1
{

    public static void main(String[] args)
    {
        String inputCharSeq = "Peter Welcome to India.";

        String regex = ".*Welcome.*";

        /*
         * Parameters:
         *
         * regex - The expression to be compiled
         *
         * input - The character sequence to be matched
         *
         * Returns:
         *
         * whether or not the regular expression matches on
         * the input
         *
         */

        boolean isMatch = Pattern.matches(regex, inputCharSeq);
        System.out.println("The text contains 'Welcome'? = " + isMatch);
    }

}

Output

The text contains 'Welcome'? = true

RegexDemo2.java

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class RegexDemo2
{

    public static void main(String[] args)
    {
        String inputCharSeq = "Peter Welcome to India.";

        String regex = ".*WElCoMe.*";

        /*
         * Parameters:
         *
         * regex - The expression to be compiled
         *       *
         * flags - Match flags, a bit mask that may include
         * CASE_INSENSITIVE, MULTILINE, DOTALL, UNICODE_CASE,
         * CANON_EQ, UNIX_LINES, LITERAL, UNICODE_CHARACTER_CLASS and
         * COMMENTS
         *
         * Returns:
         *
         * the given regular expression compiled into a pattern with
         * the given flags
         *
         */

        Pattern patternObj = Pattern.compile(regex, Pattern.CASE_INSENSITIVE);
        /*
         * Parameters:
         *
         * input - The character sequence to be matched
         *
         * Returns:
         *
         * A new matcher for this pattern
         */

        Matcher matcher = patternObj.matcher(inputCharSeq);
        /*
         * Returns:true if, and only if, the entire region sequence matches this
         * matcher's pattern
         */

        boolean isMatched = matcher.matches();
        System.out.println("Is it a Match? = " + isMatched);
    }

}

Output

Is it a Match? = true

Click the below link to download the code:
https://sites.google.com/site/ramj2eev1/home/javabasics/RegexDemo_what_is_regex_caseinsensitive.zip?attredirects=0&d=1

Github Link:
https://github.com/ramram43210/Java/tree/master/BasicJava/RegexDemo_what_is_regex_caseinsensitive

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/ef02c9011c18b0aa670526ba89cc11f493b9b854/BasicJava/RegexDemo_what_is_regex_caseinsensitive/?at=master

See also:

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