@Test
public void testCharacter(){
    final int point = Character.codePointAt("😄", 0);
    System.out.println(point);//128516
    final char[] chars = Character.toChars(point);
    System.out.println(chars.length);//2
    System.out.println(new String(chars));//😄
}

final int charCount = Character.charCount(128516);
System.out.println(charCount);//2

public static final int MIN_SUPPLEMENTARY_CODE_POINT = 0x010000;

public static int charCount(int codePoint) {
  return codePoint >= MIN_SUPPLEMENTARY_CODE_POINT ? 2 : 1;
}

Character.isWhitespace(c);

Character.isAlphabetic(a);