UnicodePlay.java

import java.util.Arrays;
import java.util.List;

import java.util.stream.IntStream;
import java.util.stream.Collectors;
public class UnicodePlay{

  static void fmt(String fmt, Object... rest) {
    System.out.format(fmt, rest);
  }

  static String formattedCodePoint(int codePoint) {
    return String.format("U+%04X", codePoint);
  }
  
  static String formattedCodePoints(String str) {
    return str.codePoints()
      .mapToObj(UnicodePlay::formattedCodePoint)
      .collect(Collectors.joining(" "));
  }
  

  static void checkUnicode(String str) {
    var codePointsCount = Character.codePointCount(str, 0, str.length());
    fmt("%n%nChecking string %s%n", str);
    fmt("String length is: %s%n", str.length());
    fmt("Code point count is: %s%n", codePointsCount);

    fmt("List of code points: %s%n", formattedCodePoints(str));

    

    var header =   "|%3s|%4s|%8X|%5s|%5s|%16s|%n"; 
    var strheader ="|%3s|%4s|%8s|%5s|%5s|%16s|%n"; 
    fmt(strheader, "idx", "znak", "int", "is hs", "is ls", "codepointAt(idx)"); 
    IntStream.range(0, str.length())
      .forEach(i -> 
          fmt(header, 
            i, 
            Character.toString(str.codePointAt(i)), 
            (int) str.charAt(i), 
            Character.isHighSurrogate(str.charAt(i)),
            Character.isLowSurrogate(str.charAt(i)),
            formattedCodePoint(str.codePointAt(i))));


   
    fmt ("Iterate over chars%n");
    str.chars().forEach(i -> fmt("%04X ", i));
  }

  public static void main(String[] args) {
    var strings = List.of(
        "👩‍❤️‍💋‍👨",  
        "道", 
        "zażółć",
        "👨‍🍼");

    strings.forEach(UnicodePlay::checkUnicode);
  }
  
}

Looking at Emojis, code points and related Java Api