Java replace curly brackets string using replaceAll when the value is in variable, java 8

Question

I have a variable:

String content = "<xxx.xx.name>xxx.xxx.com:111</xxx.xx.name>";
String destination = "\\$\\{VAR\\}";
String source = "xxx.xxx.com:111";
content = content.replaceAll(source, destination);

Result:

result = {IllegalArgumentException@781} Method threw 'java.lang.IllegalArgumentException' exception.
detailMessage = "Illegal group reference"
cause = {IllegalArgumentException@781} "java.lang.IllegalArgumentException: Illegal group reference"
stackTrace = {StackTraceElement[5]@783} 
suppressedExceptions = {Collections$UnmodifiableRandomAccessList@773}  size = 0

But if I do:

content = content.replaceAll(source,"\\$\\{VAR\\}");

all is working fine. How can I mimic or fix the replaceAll?

Both work fine for me; can't reproduce the issue. (Java 11.0.6) — akuzminykh
– akuzminykh, Commented Sep 30, 2020 at 20:25

Lino · Accepted Answer · 2020-09-30 20:59:13Z

4

From the documentation of String.replaceAll(String, String):

Note that backslashes (\) and dollar signs ($) in the replacement string may cause the results to be different than if it were being treated as a literal replacement string;

Emphasis on the may, depending on your Java version this may fail (though I fail to reproduce your problem with Java 8, 11, 12, 15 and even the early access Java 16)

You can use Matcher.quoteReplacement(String) to escape your \ and $ chars in the replacement string, as described later on in the javadoc:

Use Matcher.quoteReplacement(java.lang.String) to suppress the special meaning of these characters, if desired.

So change your code to this (assuming you want to replace the contents with ${VAR} and not with \${VAR\}):

String content = "<xxx.xx.name>xxx.xxx.com:111</xxx.xx.name>";
String destination = Matcher.quoteReplacement("${VAR}");
String source = "xxx.xxx.com:111";
content = content.replaceAll(source, destination);

Which results in:

<xxx.xx.name>${VAR}</xxx.xx.name>

DEMO

edited Sep 30, 2020 at 20:59

answered Sep 30, 2020 at 20:44

Lino

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4 Comments

akuzminykh Over a year ago

Do you have an idea why apparently only Java 15 "fails" here?

Lino Over a year ago

@akuzminykh ernest_k commented this, but since then have removed their comment, I checked with the latest build from Java 15 and was not able to reproduce this problem.

akuzminykh Over a year ago

Yeah, I also got curious after the comment about Java 15 working. I think it's not likely that a basic method like String#replaceAll breaks because of a new Java version. If that's the case, I think it's interesting why.

Holger Over a year ago

@akuzminykh I guess, it’s not replaceAll but the processing of the string literals that changed as a side effect of adding that text blocks feature.

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