Java正则表达式replaceAll多行
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Java regex replaceAll multiline
提问by Robert
I have a problem with the replaceAll for a multiline string:
我对多行字符串的 replaceAll 有问题：
String regex = "\s*/\*.*\*/";
String testWorks = " /** this should be replaced **/ just text";
String testIllegal = " /** this should be replaced \n **/ just text";
testWorks.replaceAll(regex, "x");
testIllegal.replaceAll(regex, "x");
The above works for testWorks, but not for testIllegal!? Why is that and how can I overcome this? I need to replace something like a comment /* ... */ that spans multiple lines.
以上适用于 testWorks，但不适用于 testIllegal！？为什么会这样，我该如何克服？我需要替换像注释 /* ... */ 这样跨越多行的内容。
采纳答案by mikej
You need to use the Pattern.DOTALLflag to say that the dot should match newlines. e.g.
您需要使用Pattern.DOTALL标志来说明点应与换行符匹配。例如
Pattern.compile(regex, Pattern.DOTALL).matcher(testIllegal).replaceAll("x")
or alternatively specify the flag in the pattern using (?s)e.g.
或者使用(?s)例如在模式中指定标志
String regex = "(?s)\s*/\*.*\*/";
回答by codaddict
The meta character .matches any character other than newline. That is why your regex does not work for multi line case.
元字符.匹配除换行符以外的任何字符。这就是为什么您的正则表达式不适用于多行情况。
To fix this replace .with [\d\D]that matches anycharacter including newline.
要修复此替换.为[\d\D]匹配任何字符（包括换行符）。
回答by tchrist
Add Pattern.DOTALLto the compile, or (?s)to the pattern.
添加Pattern.DOTALL到编译或(?s)模式中。
This would work
这会工作
String regex = "(?s)\s*/\*.*\*/";
See Match multiline text using regular expression
请参见 使用正则表达式匹配多行文本
