JAVA EE: How to filter list of email addresses using asPredicate method of Pattern class

Tuesday 26 December 2017

How to filter list of email addresses using asPredicate method of Pattern class | Regex in java

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https://www.youtube.com/watch?v=mFNZpvYVTkU&list=UUhwKlOVR041tngjerWxVccw

RegexPredicateDemo.java

import java.util.Arrays;

import java.util.List;

import java.util.function.Predicate;

import java.util.regex.Pattern;

import java.util.stream.Collectors;

public class RegexPredicateDemo

{

    public static void main(String[] args)

    {

        String regex = "^(.+)@gmail.com$";

        Pattern pattern = Pattern.compile(regex);

        /*

         * Returns:The predicate which can be used for matching on a

         * string

         */

        Predicate<String> emailFilterPredicate = pattern.asPredicate();

        List<String> emailList = Arrays.asList("peter@yahoo.com",

                "bob@gmail.com", "juli@gmail.com",

                "david@rediff.com");

        /*

         *  Apply predicate filter

         */

        List<String> desiredEmailList = emailList.stream()

                                           .filter(emailFilterPredicate)

                                           .collect(Collectors.<String>toList());

        desiredEmailList.forEach(System.out::println);

    }

}

Output

bob@gmail.com

juli@gmail.com

RegexDemo.java

import java.util.Arrays;

import java.util.List;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

public class RegexDemo

{

    public static void main(String[] args)

    {

        String regex = "^(.+)@gmail.com$";

        Pattern pattern = Pattern.compile(regex);

        List<String> emailList = Arrays.asList("peter@yahoo.com",

                "bob@gmail.com", "juli@gmail.com",

                "david@rediff.com");

        for (String email : emailList)

        {

            Matcher matcher = pattern.matcher(email);

            if (matcher.matches())

            {

                System.out.println(email);

            }

        }

    }

}