Utility to transform Stream of tweets to a Stream of single words

SplitUtils.java

package de.fhro.inf.prg3.a13.utils;

import de.fhro.inf.prg3.a13.model.Tweet;

import java.util.regex.Pattern;
import java.util.stream.Stream;

/**
 * @author Peter Kurfer
 */
public abstract class SplitUtils {

    /**
     * Pattern to filter for words that are only alpha numerical
     */
    private static final Pattern ALPHA_NUMERICAL = Pattern.compile("[a-z0-9@]+");

    /**
     * Pattern to split for words
     */
    private static final Pattern WORD_SPLIT = Pattern.compile("\\W");


    private SplitUtils() {

    }

    public static Stream<String> splitTweetText(final Stream<Tweet> tweetStream) {
        return tweetStream
                .map(Tweet::getText)
                .flatMap(WORD_SPLIT::splitAsStream)
                .map(String::toLowerCase)
                .filter(word -> ALPHA_NUMERICAL.matcher(word).matches());
    }
}