使用replaceAll时遇到的奇怪问题，请大家一起来讨论一下

[yifuzhiming]

以下程序会出现
public class test {

public static void main(String[] args) {
String dd="dddddddddddd varstatus aaaaaaaaaaaaaa";
dd=dd.replaceAll("varstatus", "50$ sss");
System.out.print(dd);
}
}
异常信息如下
Exception in thread "main" java.lang.IllegalArgumentException: Illegal group reference
at java.util.regex.Matcher.appendReplacement(Unknown Source)
at java.util.regex.Matcher.replaceAll(Unknown Source)
at java.lang.String.replaceAll(Unknown Source)

如果我把程序修改如下就正常了

public class test {

public static void main(String[] args) {
String dd="dddddddddddd varstatus aaaaaaaaaaaaaa";
dd=dd.replaceAll("varstatus", "50% sss");
System.out.print(dd);
}
}
仔细看就是一个‘%’的问题

[奋斗并快乐着]

是很奇怪.$在正则表达式里匹配一行的末尾,
改成dd=dd.replaceAll("varstatus", "50\\$ sss");就没问题了.
但是replaceAll只有第一个参数是正则表达式，还没见过哪里说第二个参数也是正则表达式.

[jackey024]

// The first number is always a group
int refNum = (int)replacement.charAt(cursor) - '0';
if ((refNum < 0)||(refNum > 9))
throw new IllegalArgumentException(
"Illegal group reference");

[jackey024]

看看源代码就可以了对 $ 由处理的
while (cursor < replacement.length()) {
char nextChar = replacement.charAt(cursor);
if (nextChar == '\\') {
cursor++;
nextChar = replacement.charAt(cursor);
result.append(nextChar);
cursor++;
} else if (nextChar == '$') {
// Skip past $
cursor++;

// The first number is always a group
int refNum = (int)replacement.charAt(cursor) - '0';
if ((refNum < 0)||(refNum > 9))
throw new IllegalArgumentException(
"Illegal group reference");
cursor++;

[malligator]

＄是有意义的。
＄０，＄１，．．．分别对应前面匹配的整个串，　第一个括号括起来的组，．．．

[混沌骑士]

牛 看源代码是正道

[yifuzhiming]

还没搞懂啊，高手门，不过结了结了