ApplicationMain.java

package com.octagon;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URISyntaxException;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class ApplicationMain {
    private static final String DELIMITER = " ";

    public static void main(String[] args) throws URISyntaxException, IOException {

        Set<String> stopwords = new HashSet<>();
        Set<String> fileNames = new HashSet<>();
        Boolean upperCaseFlag = Boolean.FALSE;

        for (int i = 0; i < args.length; i += 2) {
            if ("-F".equals(args[i])) {
                fileNames = paramsToSet(args[i + 1]);
                System.out.println(fileNames);
            } else if ("-S".equals(args[i])) {
                stopwords = paramsToSet(args[i + 1]);
                System.out.println(stopwords);
            } else if ("-L".equals(args[i])) {
                upperCaseFlag = Boolean.TRUE;
                System.out.println(upperCaseFlag);
            }
        }

        for (String fileName : fileNames) {
            int count = countWords(stopwords, upperCaseFlag, fileName);
            System.out.printf("%s has %d words , stopwordsFlag %b , upperCaseFlag %b", fileName, count,
                              !stopwords.isEmpty(), upperCaseFlag);
        }

    }

    private static Set<String> paramsToSet(String arg) {
        return Arrays.stream(arg.split(","))
                     .collect(Collectors.toSet());
    }

    private static int countWords(Set<String> stopwords, Boolean upperCaseFlag, String fileName) throws IOException, URISyntaxException {
        Stream<String> lines = readFile(fileName);

        //flattened words
        List<String> words = lines.flatMap(line -> Arrays.stream(line.trim().split(DELIMITER)))
                                  .filter(word -> isStopWord(word, stopwords))
                                  .filter(word -> isUpperCase(word, upperCaseFlag))
                                  .collect(Collectors.toList());

        return words.size();
    }

    public static Stream<String> readFile(String fileName) throws IOException, URISyntaxException {
        InputStream resource = ApplicationMain.class.getClassLoader().getResourceAsStream(fileName);

        InputStreamReader inputStreamReader = new InputStreamReader(
                resource,
                StandardCharsets.UTF_8
        );
        return new BufferedReader(inputStreamReader).lines();
    }


    private static boolean isUpperCase(String word, boolean upperCaseFlag) {
        if (!upperCaseFlag) return true;
        return !word.isEmpty() && Character.isUpperCase(word.charAt(0));
    }

    private static boolean isStopWord(String word, Set<String> stopwords) {
        return !word.isEmpty() && !stopwords.contains(word);
    }
}