java替换最后一个（）
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java replaceLast()
提问by Carlos Blanco
Is there replaceLast()in Java? I saw there is replaceFirst().
有没有replaceLast()在Java中？我看到有replaceFirst()。
EDIT: If there is not in the SDK, what would be a good implementation?
编辑：如果 SDK 中没有，什么是好的实现？
采纳答案by Bart Kiers
It could (of course) be done with regex:
它可以（当然）用正则表达式完成：
public class Test {
public static String replaceLast(String text, String regex, String replacement) {
return text.replaceFirst("(?s)"+regex+"(?!.*?"+regex+")", replacement);
}
public static void main(String[] args) {
System.out.println(replaceLast("foo AB bar AB done", "AB", "--"));
}
}
although a bit cpu-cycle-hungrywith the look-aheads, but that will only be an issue when working with very large strings (and many occurrences of the regex being searched for).
虽然前瞻有点cpu-cycle-hungry，但这只会在处理非常大的字符串（以及正在搜索的许多正则表达式）时出现问题。
A short explanation (in case of the regex being AB):
简短说明（如果正则表达式为AB）：
(?s) # enable dot-all option
A # match the character 'A'
B # match the character 'B'
(?! # start negative look ahead
.*? # match any character and repeat it zero or more times, reluctantly
A # match the character 'A'
B # match the character 'B'
) # end negative look ahead
EDIT
编辑
Sorry to wake up an old post. But this is only for non-overlapping instances. For example
.replaceLast("aaabbb", "bb", "xx");returns"aaaxxb", not"aaabxx"
很抱歉唤醒旧帖子。但这仅适用于非重叠实例。例如
.replaceLast("aaabbb", "bb", "xx");返回"aaaxxb"，而不是"aaabxx"
True, that could be fixed as follows:
确实，可以按如下方式修复：
public class Test {
public static String replaceLast(String text, String regex, String replacement) {
return text.replaceFirst("(?s)(.*)" + regex, "" + replacement);
}
public static void main(String[] args) {
System.out.println(replaceLast("aaabbb", "bb", "xx"));
}
}
回答by Joachim Sauer
See for yourself: String
你自己看： String
Or is your question actually "How do I implement a replaceLast()?"
或者你的问题实际上是“我如何实现一个replaceLast()？”
Let me attempt an implementation (this should behave pretty much like replaceFirst(), so it should support regexes and backreferences in the replacement String):
让我尝试一个实现（这应该表现得非常像replaceFirst()，所以它应该支持替换字符串中的正则表达式和反向引用）：
public static String replaceLast(String input, String regex, String replacement) {
Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(input);
if (!matcher.find()) {
return input;
}
int lastMatchStart=0;
do {
lastMatchStart=matcher.start();
} while (matcher.find());
matcher.find(lastMatchStart);
StringBuffer sb = new StringBuffer(input.length());
matcher.appendReplacement(sb, replacement);
matcher.appendTail(sb);
return sb.toString();
}
回答by Thomas
No.
不。
You could do reverse/ replaceFirst/ reverse, but it's a bit expensive.
你可以做reverse/ replaceFirst/ reverse，但它是一个有点贵。
回答by Mihir Mathuria
You can combine StringUtils.reverse()with String.replaceFirst()
您可以结合StringUtils.reverse()使用String.replaceFirst()
回答by BalusC
If you don't need regex, here's a substring alternative.
如果您不需要正则表达式，这里有一个子字符串替代方案。
public static String replaceLast(String string, String toReplace, String replacement) {
int pos = string.lastIndexOf(toReplace);
if (pos > -1) {
return string.substring(0, pos)
+ replacement
+ string.substring(pos + toReplace.length());
} else {
return string;
}
}
Testcase:
测试用例：
public static void main(String[] args) throws Exception {
System.out.println(replaceLast("foobarfoobar", "foo", "bar")); // foobarbarbar
System.out.println(replaceLast("foobarbarbar", "foo", "bar")); // barbarbarbar
System.out.println(replaceLast("foobarfoobar", "faa", "bar")); // foobarfoobar
}
回答by Whimusical
If the inspected string is so that
如果检查的字符串是这样的
myString.endsWith(substringToReplace) == true
you also can do
你也可以
myString=myString.replaceFirst("(.*)"+myEnd+"$",""+replacement)
回答by AvrDragon
it is slow, but works:3
它很慢，但有效：3
import org.apache.commons.lang.StringUtils;
public static String replaceLast(String str, String oldValue, String newValue) {
str = StringUtils.reverse(str);
str = str.replaceFirst(StringUtils.reverse(oldValue), StringUtils.reverse(newValue));
str = StringUtils.reverse(str);
return str;
}
回答by MushyPeas
split the haystack by your needle using a lookahead regex and replace the last element of the array, then join them back together :D
使用前瞻正则表达式用针分割干草堆并替换数组的最后一个元素，然后将它们重新连接在一起：D
String haystack = "haystack haystack haystack";
String lookFor = "hay";
String replaceWith = "wood";
String[] matches = haystack.split("(?=" + lookFor + ")");
matches[matches.length - 1] = matches[matches.length - 1].replace(lookFor, replaceWith);
String brandNew = StringUtils.join(matches);
回答by PhantomKid
use replaceAll and add a dollar sign right after your pattern:
使用 replaceAll 并在您的模式后添加一个美元符号：
replaceAll("pattern$", replacement);
回答by xhay
I also have encountered such a problem, but I use this method:
我也遇到过这样的问题，不过我用的是这个方法：
public static String replaceLast2(String text,String regex,String replacement){
int i = text.length();
int j = regex.length();
if(i<j){
return text;
}
while (i>j&&!(text.substring(i-j, i).equals(regex))) {
i--;
}
if(i<=j&&!(text.substring(i-j, i).equals(regex))){
return text;
}
StringBuilder sb = new StringBuilder();
sb.append(text.substring(0, i-j));
sb.append(replacement);
sb.append(text.substring(i));
return sb.toString();
}
