Code modifications by lambda and Streams

[Avante]

I've done a program that counts how many times every word is repeated in the file I'm trying to do with lambda and Streams, but it doesn't work.

Map<String, Integer> wordCount = new HashMap<String, Integer>();
    String[] words = learn.split(" ");

    for (int i=0 ; i &lt; words.length ; i++){
        if (!wordCount.containsKey(words[i])){
            wordCount.put(words[i],1);
        } else{
            wordCount.put(words[i],wordCount.get(words[i])+1);
        }
    }
    Set&lt;Map.Entry&lt;String, Integer&gt;&gt; setOfEntries = wordCount.entrySet();
    Iterator&lt;Map.Entry&lt;String, Integer&gt;&gt; iterator = setOfEntries.iterator();
    while (iterator.hasNext()) {
        Map.Entry&lt;String, Integer&gt; entry = iterator.next();
        Integer value = entry.getValue();
        String key = entry.getKey();
        if ((value.compareTo(Integer.valueOf(10)) &lt;0) || key.length() &lt;4)  {

            iterator.remove();
        }
    }
    List&lt;Map.Entry&lt;String, Integer&gt;&gt; list = new ArrayList&lt;&gt;();
    list.addAll(wordCount.entrySet());

How can this piece of code be changed with lambda and Streams

[inna]

• Help Files.lines Get a stream in the file. Stream<String>
• Every line to break into words and use flatMap for conversion
• If necessary, filter the words in length
• Use Collectors.groupingBy + Collectors.counting for a map of the frequency of words Map<String, Long>

Map<String, Long> wordFreq = Files.lines(Paths.get("input.txt")) // Stream<String>
    .flatMap(line -> Arrays.stream(line.split("\\s+")))
    .filter(word -> word.length() > 2) // игнорировать слова короче 3 символов
    .collect(Collectors.groupingBy(
        word -> word,
        Collectors.counting()
    ));

Integer frequency can be used Collectors.summingInt:

// ...
    .collect(Collectors.groupingBy(
        word -> word,
        Collectors.summingInt(word -> 1) // каждому слову отвечает единица
    )); // Map<String, Integer>

The words could also lead to the same register word -> word.toLowerCase()to break not only the gaps, but also the sign of preference line -> line.split("[\\p{Punct}\\s]+")use SortedMap/TreeMap in the box or LinkedHashMap to conclude the words as they appear in the entry file, etc.