Java replaceAll with regex

Question

I have this input from the user:

*.*.*.*

(* = censor) this string is an input from the user, that's what the user wants to censor. how do I convert it to regex? Edit: Let me explain again. user wants to censor anything in * between the dots, so he types in *.*.*.*, and I need to convert it to regex. he could type text*text too

I have tried doing:

String strLine = "93.38.31.43 and 39.53.19.33 and lala.lala.lala.lala";
String input = "*.*.*.*";
String replaceWord = "[censor]";
input = input.replaceAll("\\*","\\\\\\w+");
strLine = strLine.replaceAll("(?=\\s+)\\S*)" + input + "(?=\\s+)\\S*",replaceWord);

I tried replacing the * with \\w+ to get this output:

the ip's are [censor] and [censor] and [censor]

but It does not work, doesn't replace anything.

when I'm doing it like that, it works:

strLine = strLine.replaceAll("?<=\\s+)\\S*" +"\\w+\\.\\w+\\.\\w+\\.\\w+"+"(?\\s+)\\S*",replaceWord);

why doesn't it work? is there a better way doing it?

Here's a great tool for testing Java-style regexes (and it provides the Java-escaped string too!) — dimo414
– dimo414, Commented Mar 17, 2015 at 7:30
did you copied your code and pasted it here? because you have a wrong spelling in replaceWord you typed an w instead of an e — Zorian
– Zorian, Commented Mar 17, 2015 at 7:31
what does * mean? Is it anything? Is it a digit? Is it anything but space? There are filename globs, but this input is not a file name. You should educate user about proper regular expressions or provide him some kind of constructor for that expressions. *.*.*.* looks like self-invented regular-expression-like language. You should stick to standards. — vbezhenar
– vbezhenar, Commented Mar 17, 2015 at 7:37
Let me explain. user wants to censor anything between the dots now, so he types in .*.*.*, and I need to convert it to regex. he could type text*text too — Tom S
– Tom S, Commented Mar 17, 2015 at 7:39

anubhava · Accepted Answer · 2015-03-17 08:00:13Z

1

You can use:

String strLine = "93.38.31.43 and 39.53.19.33 and lala.lala.lala.lala";
String input = "*.*.*.*";
String replaceWord = "[censor]";

input = input.replace("*","\\w+").replace(".", "\\.");
System.out.println(input); // \w+\.\w+\.\w+\.\w+

strLine = strLine.replaceAll("\\b" + input + "\\b", replaceWord);
System.out.println(strLine);
//=> [censor] and [censor] and [censor]

answered Mar 17, 2015 at 8:00

anubhava

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5 Comments

Tom S Over a year ago

input = input.replace("*","\\w+").replace(".", "\\."); gives me an error.

glglgl Over a year ago

@Tom An error. Wow. The content of the error message is a secret?

Tom S Over a year ago

I fixed it adding \\ before the special chars and using replaceAll

Tom S Over a year ago

Yes I know, weird. I'm using Eclipse and it gives me an error unless I will add \\ before

anubhava Over a year ago

input.replaceAll("\\*","\\\\\\w+").replaceAll("\\.", "\\\\."); uses regex replacement and input = input.replace("*","\\w+").replace(".", "\\."); just does String replacement. Both should work.

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