Assume a paragraph:

String paragraph = "Java streams make processing strings easy. Streams in Java are powerful.";

Approach 1: Using split() + groupingBy

Map<String, Long> wordCount = Arrays.stream(paragraph.split("\\s+"))
    .map(word -> word.replaceAll("\\p{Punct}", "").toLowerCase()) // remove punctuation
    .collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));

System.out.println(wordCount);

Approach 2: Using Pattern + Matcher.results() (Unicode-aware, Java 9+)

Pattern pattern = Pattern.compile("\\p{L}+"); // matches Unicode letters

Map<String, Long> wordCount2 = pattern.matcher(paragraph).results()
    .map(m -> m.group().toLowerCase())
    .collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));

System.out.println(wordCount2);