使用Java和RegEx转换字符串中的大小写 [英] Use Java and RegEx to convert casing in a string
问题描述
问题:转
"My Testtext TARGETSTRING My Testtext"
进入
"My Testtext targetstring My Testtext"
Perl支持\ L - 操作,可以在替换字符串中使用。
Perl supports the "\L"-operation which can be used in the replacement-string.
Pattern-Class不支持此操作:
The Pattern-Class does not support this operation:
Perl构造不此类支持:
[...]
预处理操作\l \ u,\ L和\U。
https:// docs。 oracle.com/javase/10/docs/api/java/util/regex/Pattern.html
推荐答案
你不能在Java正则表达式中这样做。您必须使用 String.toUpperCase()
和 toLowerCase()
。
You can't do this in Java regex. You'd have to manually post-process using String.toUpperCase()
and toLowerCase()
instead.
这是一个如何使用正则表达式来查找和大写句子中长度至少为3的单词的示例
Here's an example of how you use regex to find and capitalize words of length at least 3 in a sentence
String text = "no way oh my god it cannot be";
Matcher m = Pattern.compile("\\b\\w{3,}\\b").matcher(text);
StringBuilder sb = new StringBuilder();
int last = 0;
while (m.find()) {
sb.append(text.substring(last, m.start()));
sb.append(m.group(0).toUpperCase());
last = m.end();
}
sb.append(text.substring(last));
System.out.println(sb.toString());
// prints "no WAY oh my GOD it CANNOT be"
注意 appendReplacement
和 appendTail
请注意,上面的解决方案使用 substring
并管理 tail
索引等。事实上,你可以去如果你使用 Matcher.appendReplacement
和 appendTail
。
Note on appendReplacement
and appendTail
Note that the above solution uses substring
and manages a tail
index, etc. In fact, you can go without these if you use Matcher.appendReplacement
and appendTail
.
StringBuffer sb = new StringBuffer();
while (m.find()) {
m.appendReplacement(sb, m.group().toUpperCase());
}
m.appendTail(sb);
注意 sb
现在是 StringBuffer
而不是 StringBuilder
。直到 Matcher
提供 StringBuilder
重载,你才会遇到速度较慢的 StringBuffer
如果你想使用这些方法。
Note how sb
is now a StringBuffer
instead of StringBuilder
. Until Matcher
provides StringBuilder
overloads, you're stuck with the slower StringBuffer
if you want to use these methods.
这取决于你是否可以降低效率以获得更高的可读性。
It's up to you whether the trade-off in less efficiency for higher readability is worth it or not.
StringBuilder
andStringBuffer
in Java
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