java 正则表达式“\\p{Z}”是什么意思？
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What does regex "\\p{Z}" mean?
提问by BRabbit27
I am working with some code in java that has an statement like
我正在使用 java 中的一些代码，其中包含类似的语句
String tempAttribute = ((String) attributes.get(i)).replaceAll("\p{Z}","")
I am not used to regex, so what is the meaning of it? (If you could provide a website to learn the basics of regex that would be wonderful) I've seen that for a string like
我不习惯正则表达式，那么它的含义是什么？（如果你能提供一个网站来学习正则表达式的基础知识，那就太好了）我见过这样的字符串
ept as yit gets transformed into eptasy, but this doesn't seem right. I believe the guy who wrote this wanted to trim leading and trailing spaces maybe.
ept as y它变成了eptasy，但这似乎不对。我相信写这篇文章的人可能想修剪前导和尾随空格。
回答by Alex Shesterov
It removes all the whitespace (replaces all whitespace matches with empty strings).
它删除所有空格（用空字符串替换所有空格匹配）。
A wonderful regex tutorial is available at regular-expressions.info. A citation from this site:
一个精彩的正则表达式教程可在regular-expressions.info 获得。来自本网站的引文：
\p{Z} or \p{Separator}: any kind of whitespace or invisible separator.
\p{Z} 或 \p{Separator}：任何类型的空格或不可见分隔符。
回答by sbecker11
The OP stated that the code fragment was in Java. To comment on the statement:
OP 表示代码片段是用 Java 编写的。评论该声明：
\p{Z} or \p{Separator}: any kind of whitespace or invisible separator.
\p{Z} 或 \p{Separator}：任何类型的空格或不可见分隔符。
the sample code below shows that this does not apply in Java.
下面的示例代码表明这不适用于 Java。
public static void main(String[] args) {
// some normal white space characters
String str = "word1 \t \n \f \r " + '\u000B' + " word2";
// various regex patterns meant to remove ALL white spaces
String s = str.replaceAll("\s", "");
String p = str.replaceAll("\p{Space}", "");
String b = str.replaceAll("\p{Blank}", "");
String z = str.replaceAll("\p{Z}", "");
// \s removed all white spaces
System.out.println("s [" + s + "]\n");
// \p{Space} removed all white spaces
System.out.println("p [" + p + "]\n");
// \p{Blank} removed only \t and spaces not \n\f\r
System.out.println("b [" + b + "]\n");
// \p{Z} removed only spaces not \t\n\f\r
System.out.println("z [" + z + "]\n");
// NOTE: \p{Separator} throws a PatternSyntaxException
try {
String t = str.replaceAll("\p{Separator}","");
System.out.println("t [" + t + "]\n"); // N/A
} catch ( Exception e ) {
System.out.println("throws " + e.getClass().getName() +
" with message\n" + e.getMessage());
}
} // public static void main
The output for this is:
这个的输出是：
s [word1word2]
p [word1word2]
b [word1
word2]
z [word1
word2]
throws java.util.regex.PatternSyntaxException with message
Unknown character property name {Separator} near index 12
\p{Separator}
^
This shows that in Java \\p{Z} removes only spaces and not "any kind of whitespace or invisible separator".
这表明在 Java 中 \\p{Z} 仅删除空格而不是“任何类型的空格或不可见分隔符”。
These results also show that in Java \\p{Separator} throws a PatternSyntaxException.
这些结果还表明，在 Java 中 \\p{Separator} 会抛出 PatternSyntaxException。
回答by Tung Linh
First of all, \pmeans you are going to match a class, a collection of character, not single one. For reference, this is Javadoc of Pattern class. https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html
首先， \p意味着您将匹配一个类，一个字符集合，而不是单个字符。作为参考，这是 Pattern 类的 Javadoc。https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html
Unicode scripts, blocks, categories and binary properties are written with the \p and \P constructs as in Perl. \p{prop} matches if the input has the property prop, while \P{prop} does not match if the input has that property.
Unicode 脚本、块、类别和二进制属性是用 \p 和 \P 结构编写的，就像在 Perl 中一样。\p{prop} 匹配输入是否具有属性 prop，而 \P{prop} 不匹配如果输入具有该属性。
And then Zis the name of a class (collection,set) of characters. In this case, it's abbreviation of Separator. Separatorcontaints 3 sub classes: Space_Separator(Zs), Line_Separator(Zl) and Paragraph_Separator(Zp).
然后Z是字符类（集合、集合）的名称。在这种情况下，它是 的缩写Separator。Separator包含 3 个子类：Space_Separator(Zs)、Line_Separator(Zl) 和Paragraph_Separator(Zp)。
Refer here for which characters those classes contains here: Unicode Character Databaseor Unicode Character Categories
请参阅此处了解这些类包含哪些字符：Unicode 字符数据库或 Unicode 字符类别
More document: http://www.unicode.org/reports/tr18/#General_Category_Property
更多文件：http: //www.unicode.org/reports/tr18/#General_Category_Property
