#CODEPOINTS IN JAVA CODE#

Let that sink in: this means that the char type (as well as the Character class) in Java is not what we usually mean by a character.

#CODEPOINTS IN JAVA CODE#

So if you have one supplementary character that consists of two Code Units, the length of that single character is two. The length is equal to the number of Unicode code units in the string. Let's take a look at the Javadoc of the length() method of the String class it says the followings: Unicode Code Point: U+1D538 (see: /U+1D538)Īs you can see here A is encoded by one Code Unit while 𝔸 is encoded by two. The key thing here is that one or more Code Units may be required to encode a Code Point (character).

Supplementary characters ( Code Points) are encoded in two Code Units (see Wikipedia - UTF-16 for more information). The other planes contain the 'supplementary' characters (from U+10000 to U+10FFFF).Ĭharacters ( Code Points) from the first plane are encoded in one 16-bit Code Unit with the same value. The first plane, the Basic Multilingual Plane (BMP) contains the 'classic' characters (from U+0000 to U+FFFF). Unicode Code Points are logically divided into 17 planes (groups). Not the only way but that is what Java uses. Code Unit is a bit sequence used to encode a character ( Code Point)Īs I mentioned above, UTF-16 is a way to encode Unicode characters.Code Point is a unique integer value that identifies a character.There are two important Unicode terms here, you need to know about: Code Point and Code Unit. That's why the size of the Java char type is 2 bytes (2x8 = 16 bits). Unicode is a standard to represent text while UTF-16 is a way to encode Unicode characters. To understand the weirdness in Strings, you need to be familiar with some Encoding/Unicode terms.Īs you might know, Java uses UTF-16 to encode Unicode text.

In the rest of the article, I'm going to explain why you might got unexpected results in the quiz and give you a few suggestions to avoid issues. What do you think, what is the length of the following Strings in Java?īy now, you might get why 'Confusing Java Strings' is the title of this article. In order to demonstrate this, let me invite you for a little quiz: I also prepared a GitHub repo for you where you can find some code that you can use to try the examples out on your own: /jonatan-ivanov/java-strings-demo. Two well-known standards for assigning numbers to symbols are ASCII and Unicode.

In this article, I would like to show you a couple of confusing things in connection with Java Strings and give you a few suggestions to avoid issues with them. A Code point is a number that identifies a symbol.

Codepoints in java