java 如何使用正则表达式替换字符串中的最后一个点？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/4094024/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How to replace last dot in a string using a regular expression?
提问by digiarnie
I'm trying to replace the last dot in a String using a regular expression.
我正在尝试使用正则表达式替换字符串中的最后一个点。
Let's say I have the following String:
假设我有以下字符串：
String string = "hello.world.how.are.you!";
I want to replace the last dot with an exclamation mark such that the result is:
我想用感叹号替换最后一个点，结果是：
"hello.world.how.are!you!"
I have tried various expressions using the method String.replaceAll(String, String)without any luck.
我尝试了使用该方法的各种表达式，String.replaceAll(String, String)但没有任何运气。
回答by codaddict
One way would be:
一种方法是：
string = string.replaceAll("^(.*)\.(.*)$","!");
Alternatively you can use negative lookahead as:
或者，您可以使用负前瞻作为：
string = string.replaceAll("\.(?!.*\.)","!");
回答by paxdiablo
Although you can use a regex, it's sometimes best to step back and just do it the old-fashioned way. I've always been of the belief that, if you can't think of a regex to do it in about two minutes, it's probably not suited to a regex solution.
虽然您可以使用正则表达式，但有时最好退后一步，按照老式的方式来做。我一直相信，如果你想不出一个正则表达式在大约两分钟内完成它，它可能不适合正则表达式解决方案。
No doubt get some wonderful regex answers here. Some of them may even be readable :-)
毫无疑问，在这里可以得到一些精彩的正则表达式答案。其中一些甚至可能是可读的:-)
You can use lastIndexOfto get the last occurrence and substringto build a new string: This complete program shows how:
您可以使用lastIndexOf获取最后一次出现并substring构建一个新字符串：这个完整的程序显示了如何：
public class testprog {
public static String morph (String s) {
int pos = s.lastIndexOf(".");
if (pos >= 0)
return s.substring(0,pos) + "!" + s.substring(pos+1);
return s;
}
public static void main(String args[]) {
System.out.println (morph("hello.world.how.are.you!"));
System.out.println (morph("no dots in here"));
System.out.println (morph(". first"));
System.out.println (morph("last ."));
}
}
The output is:
输出是：
hello.world.how.are!you!
no dots in here
! first
last !
回答by John La Rooy
The regex you need is \\.(?=[^.]*$). the ?=is a lookahead assertion
您需要的正则表达式是\\.(?=[^.]*$). 这?=是一个前瞻断言
"hello.world.how.are.you!".replace("\.(?=[^.]*$)", "!")
回答by panticz
Try this:
试试这个：
string = string.replaceAll("[.]$", "");
