java - 将整个单词与字符串中的前导或尾随特殊符号(如美元)匹配

Question

我可以使用 Matcher.quoteReplacement 替换美元符号。我可以通过添加边界字符来替换单词:

from = "\\b" + from + "\\b"; 
outString = line.replaceAll(from, to);

但我似乎无法将它们组合起来用美元符号替换单词。

这是一个例子。我正在尝试将“$temp4”(不是 $temp40)替换为“register1”。

        String line = "add, $temp4, $temp40, 42";
        String to = "register1";
        String from = "$temp4";
        String outString;


        from = Matcher.quoteReplacement(from);
        from = "\\b" + from + "\\b";  //do whole word replacement

        outString = line.replaceAll(from, to);
        System.out.println(outString);

输出

"add, $temp4, $temp40, 42"

如何让它替换 $temp4 并且仅替换 $temp4？

Answer 1

使用明确的单词边界，(?<!\w)和(?!\w) ，而不是 \b取决于上下文:

from = "(?<!\\w)" + Pattern.quote(from) + "(?!\\w)";

请参阅regex demo .

(?<!\w)是一个负向后查找，如果当前位置和 (?!\w) 左侧紧邻一个非单词字符，则匹配失败是一个否定的前瞻，如果当前位置右侧紧邻非单词字符，则匹配失败。 Pattern.quote(from)必须转义 from 中的任何特殊字符变量。

请参阅Java demo :

String line = "add, $temp4, $temp40, 42";
String to = "register1";
String from = "$temp4";
String outString;

from = "(?<!\\w)" + Pattern.quote(from) + "(?!\\w)";

outString = line.replaceAll(from, to);
System.out.println(outString);
// => add, register1, $temp40, 42