Speedup by removing non pattern replaceAll with constant arg

[tbw777]

replaceAll("ABC", "") is non Pattern method and therefore must be replaced to simple fast replace()
A proofs of changes: https://gist.github.com/tbw777/8a6ef60af21487c5faec67037099fd0b

[markt-asf]

Thanks for this PR - these are good changes to have.

[tbw777]

@markt-asf
Branch was updated and https://gist.github.com/tbw777/8a6ef60af21487c5faec67037099fd0b also
Check please.

[ChristopherSchultz]

There isn't much of a difference between String.replace and String.replaceAll. They both use regular expressions under the hood. Java's Pattern class has a special case for "this search-string doesn't include any metacharacters" (it's a flag called LITERAL) and has optimized code-paths for those cases.

IMO replaceAll is more clear than replace because it's absolutely clear that all instances will be replaced in the string.

If performance is the primary factor, here, we should use an implementation of string-replacement that does not involve creating Pattern and Matcher objects and re-encoding the replacement String every single time.

[ChristopherSchultz]

I think this "performance improvement" is not an improvement and doesn't affect performance in any meaningful way.

[ChristopherSchultz]

Apologies: my comments are rubbish after Java 9. Please forgive the noise.

[happyhua]

A replaceAll -> replace change in for example java/org/apache/tomcat/buildutil/translate/Utils.java can produce different output.

        String source = "1\t2\t3";

        System.out.println("source: " + source);
        System.out.println("replaceAll: " + source.replaceAll("\t", "\\t"));
        System.out.println("replace: " + source.replace("\t", "\\t"));

source: 1	2	3
replaceAll: 1t2t3
replace: 1\t2\t3