Java charAt used with characters that have two code units

by

It sounds like tho book is saying that ‘ℤ’ is not a UTF-16 character in the basic multilingual plane, but in fact it is.

Java uses UTF-16 with surrogate pairs for characters that are not in the basic multilingual plane. Since ‘ℤ’ (0x2124) is in the basic multilingual plane it is represented by a single code unit. In your example sentence.charAt(0) will return ‘ℤ’, and sentence.charAt(1) will return ‘ ‘.

A character represented by surrogate pairs has two code units making up the character. sentence.charAt(0) would return the first code unit, and sentence.charAt(1) would return the second code unit.

See http://docs.oracle.com/javase/6/docs/api/java/lang/String.html:

A String represents a string in the UTF-16 format in which
supplementary characters are represented by surrogate pairs (see the
section Unicode Character Representations in the Character class for
more information). Index values refer to char code units, so a
supplementary character uses two positions in a String.

More Related Contents:

  1. What is a “surrogate pair” in Java?
  2. JavaScript strings outside of the BMP
  3. Why does the Java char primitive take up 2 bytes of memory?
  4. Difference between UTF-8 and UTF-16?
  5. How does Java store UTF-16 characters in its 16-bit char type?
  6. Byte and char conversion in Java
  7. Remove diacritical marks (ń ǹ ň ñ ṅ ņ ṇ ṋ ṉ ̈ ɲ ƞ ᶇ ɳ ȵ) from Unicode chars
  8. What is the Java’s internal represention for String? Modified UTF-8? UTF-16?
  9. Get unicode value of a character
  10. how to add unicode in truetype0font on pdfbox 2.0.0?
  11. Java equivalent to JavaScript’s encodeURIComponent that produces identical output?
  12. ‘Fill’ Unicode characters in labels
  13. Passing command line unicode argument to Java code
  14. Java regex for support Unicode?
  15. How do I correctly decode unicode parameters passed to a servlet
  16. Creating Unicode character from its number
  17. Write a file in UTF-8 using FileWriter (Java)?
  18. how to use chinese and japanese character as string in java?
  19. Java Unicode encoding
  20. Display an Unicode character on JButton
  21. How to make the Java.awt.Robot type unicode characters? (Is it possible?)
  22. Regex: what is InCombiningDiacriticalMarks?
  23. File.listFiles() mangles unicode names with JDK 6 (Unicode Normalization issues)
  24. How can I open files containing accents in Java?
  25. Why does Java permit escaped unicode characters in the source code?
  26. How to use Special Chars in Java/Eclipse
  27. Character display/search for Unicode characters
  28. Why does this code, written backwards, print “Hello World!”
  29. Java: Convert String “\uFFFF” into char
  30. First character of the reading from the text file :  [duplicate]

Leave a Comment