java 只匹配字符串的第一个和最后一个字符
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Match only first and last character of a string
提问by Sinker
I had a look at other stackoverflowquestions and couldn't find one that asked the same question, so here it is:
我查看了其他stackoverflow问题，但找不到提出相同问题的问题，所以这里是：
How do you match the first and last characters of a string (can be multi-line or empty).
如何匹配字符串的第一个和最后一个字符（可以是多行或空）。
So for example:
例如：
String = "this is a simple sentence"
Note that the string includes the beginning and ending quotation marks.
请注意，该字符串包括开头和结尾的引号。
How do I get match the first and last characters where the string begins and ends with a quotation mark (").
如何匹配字符串以引号 (") 开头和结尾的第一个和最后一个字符。
I tried:
我试过：
^"|$" and \A"\Z"
but these do not produce the desired result.
但这些不会产生预期的结果。
Thanks for your help in advance :)
提前感谢您的帮助:)
采纳答案by wjans
Is this what you are looking for?
这是你想要的？
String input = "\"this is a simple sentence\"";
String result = input.replaceFirst("(?s)^\"(.*)\"$", " ");
This will replace the first and last character of the input string with spaces if it starts and ends with ". It will also work across multiple lines since the DOTALLflag is specified by (?s).
如果输入字符串的开头和结尾以". 由于DOTALL标志由(?s).
回答by Bohemian
The regex that matches the whole input ".*". In java, it looks like this:
匹配整个 input 的正则表达式".*"。在java中，它看起来像这样：
String regex = "\".*\"";
System.out.println("\"this is a simple sentence\"".matches(regex)); // true
System.out.println("this is a simple sentence".matches(regex)); // false
System.out.println("this is a simple sentence\"".matches(regex)); // false
If you want to removethe quotes, use this:
如果要删除引号，请使用以下命令：
String input = "\"this is a simple sentence\"";
input = input.replaceAll("(^\"|\"$)", "")); // this is a simple sentence (without any quotes)
If you want this to work over multiple lines, use this:
如果您希望它在多行上工作，请使用：
String input = "\"this is a simple sentence\"\n\"and another sentence\"";
System.out.println(input + "\n");
input = input.replaceAll("(?m)(^\"|\"$)", "");
System.out.println(input);
which produces output:
产生输出：
"this is a simple sentence"
"and another sentence"
this is a simple sentence
and another sentence
Explanation of regex (?m)(^"|"$):
正则表达式的解释(?m)(^"|"$)：
(?m)means "Caret and dollar match after and before newlines for the remainder of the regular expression"(^"|"$)means^"OR"$, which means "start of line then a double quote" OR "double quote then end of line"
(?m)表示“正则表达式其余部分的换行符前后的插入符和美元匹配”(^"|"$)意味着^"OR"$，这意味着“行首然后双引号”或“双引号然后行尾”
回答by Kaj
String regexp = "(?s)\".*\"";
String data = "\"This is some\n\ndata\"";
Matcher m = Pattern.compile(regexp).matcher(data);
if (m.find()) {
System.out.println("Match starts at " + m.start() + " and ends at " + m.end());
}
回答by Sanjay T. Sharma
Why not use the simple logic of getting the first and last characters based on charAtmethod of String? Place a few checks for empty/incomplete strings and you should be done.
为什么不使用基于charAtString的方法获取第一个和最后一个字符的简单逻辑？对空/不完整的字符串进行一些检查，您应该完成。
