Note methods like Character.toChars(int) that return an array of chars.
#Java string to codepoints code
The Character class contains many useful methods for working with Unicode code points. For example, Character.isLetter(0x2F81A) returns true because the code point value represents a letter (a CJK ideograph).Ĭasting the char to an int, as you do in your sample, works fine though. The methods that accept an int value support all Unicode characters, including supplementary characters.For example, Character.isLetter('\uD840') returns false, even though this specific value if followed by any low-surrogate value in a string would represent a letter. They treat char values from the surrogate ranges as undefined characters. The methods that only accept a char value cannot support supplementary characters.I guess to preserve backward compatibility that was not changed when Unicode 2.0 came around and caution is needed when dealing with them. For code points exceeding U+FFFF the code point is represented by a surrogate pair, i.e., two chars with the first being the high-surrogates code unit, (in the range \uD800-\uDBFF), the second being the low-surrogate code unit (in the range \uDC00-\uDFFF).įrom the early days, all basic Character methods were based on the assumption that a code point could be represented in one char, so that's what the method signatures look like. Java internally represents all Strings in UTF-16 format. A year later, when Unicode 2.0 was implemented, the concept of surrogate characters was introduced to go beyond the 16 bit limit. A little bit of background: When Java appeared in 1995, the char type was based on the original " Unicode 88" specification, which was limited to 16 bits.
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