RFR 8214971 : Replace use of string.equals("") with isEmpty()

Stuart Marks stuart.marks at oracle.com
Fri Dec 7 02:56:00 UTC 2018

On 12/6/18 2:42 PM, Claes Redestad wrote:
> I filed this bug after seeing it in startup profiles, where isEmpty() avoids an 
> instanceof and four(!) method calls, so getting rid of a few of these has a 
> measurable impact on startup. It seemed prudent to just replace it all while 
> we're at it.

Interesting. The compact strings stuff saves a lot of space, but it means that 
more setup work needs to be done before an actual equality comparison can be 
done. Thus, equals("") has gotten quite a bit more expensive relative to 
isEmpty() compared with the situation prior to compact strings.

Still, it seems like a method call could be saved here:

         if (anObject instanceof String) {
             String aString = (String)anObject;
             if (coder() == aString.coder()) {
                 return isLatin1() ? StringLatin1.equals(value, aString.value)
                                   : StringUTF16.equals(value, aString.value);

by saving the result of coder() in a local variable and then comparing it 
directly to LATIN1. Is it worth it?

(Note, this isn't relevant to the current review.)


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