search-stream-regex.java

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

private final Pattern pattern = Pattern.compile(SEARCH_TOKEN);

public List<String> searchStreamRegex() {

    InputStream inputStream = new FileInputStream(pathFile);
    // lazy loading
    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
    Stream<String> linesStream = bufferedReader.lines();
    return linesStream.filter(a -> pattern.matcher(a).find()).collect(Collectors.toList());

}

related to medium article https://gae-piaz.medium.com/search-string-in-file-with-java-as-fast-as-possible-fedafdc7a3ee