Java charAt used with characters that have two code units

Question

From Core Java, vol. 1, 9th ed., p. 69:

The character ℤ requires two code units in the UTF-16 encoding. Calling

String sentence =         


        

Answer 1

Horstmann was talking about the 'Z' which need two UTF-16 code units. Take a look at this code:

public class Main {
    public static void main(String[] args)
    {
        String a = "\uD83D\uDE02 is String";
        System.out.println("Length: " + a.length());
        System.out.println(a.charAt(0));
        System.out.println(a.charAt(1));
        System.out.println(a.charAt(2));
        System.out.println(a.charAt(3));
    }
}

in IntelliJ Idea I can't even paste the 4 byte character as one character because while pasting this emoji: