如何正确计算Java中的字符串的长度？ [英] How to correctly compute the length of a String in Java?

问题描述

我知道有 String＃length 以及 Character 中的多种方法/代码点。

Java中建议的方式是返回Unicode标准指定的结果（

解决方案 / div>

java.text.BreakIterator 可以迭代文本，并可以报告字符，单词，句子和行边界。

  def length（text：String，locale：java.util.Locale = java.util.Locale.ENGLISH）= {
 val charIterator = java.text.BreakIterator.getCharacterInstance（locale）
 charIterator.setText（text）
 
 var result = 0 
 while（charIterator.next（）！ = BreakIterator.DONE）result + = 1 
 result 
} 
  

：

  scala> val text =Thîslóo̰kswe̐ird！ 
 text：java.lang.String =Thîslóo̰kswe̐ird！ 
 
 scala> val length = length（text）
 length：Int = 17 
 
 scala> val codepoints = text.codePointCount（0，text.length）
 codepoints：Int = 21 
  

使用代理对：

  scala> val parens =\\\�\\\�surpi\\\́se！\\\�\\\�
 parens：java.lang.String =
I know there is String#length and the various methods in Character which more or less work on code units/code points.

What is the suggested way in Java to actually return the result as specified by Unicode standards (UAX#29), taking things like language/locale, normalization and grapheme clusters into account?
解决方案
java.text.BreakIterator is able to iterate over text and can report on "character", word, sentence and line boundaries.

Consider this code:
def length(text: String, locale: java.util.Locale = java.util.Locale.ENGLISH) = {
  val charIterator = java.text.BreakIterator.getCharacterInstance(locale)
  charIterator.setText(text)

  var result = 0
  while(charIterator.next() != BreakIterator.DONE) result += 1
  result
}
Running it:
scala> val text = "Thîs lóo̰ks we̐ird!"
text: java.lang.String = Thîs lóo̰ks we̐ird!

scala> val length = length(text)
length: Int = 17

scala> val codepoints = text.codePointCount(0, text.length)
codepoints: Int = 21 
With surrogate pairs:
scala> val parens = "\uDBFF\uDFFCsurpi\u0301se!\uDBFF\uDFFD"
parens: java.lang.String = 
                        
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