string1 + string2 + string3 becomes
temp=new StringBuffer(string1).append(string2) temp2= new StringBuffer(temp),apend(string3) result = temp2.toString(); and this was true until the last time I checked, which was a while ago, but It was at least using Java 5. Simone ------------------------------------------------------- Ing. Simone Giannecchini GeoSolutions S.A.S. Founder - Software Engineer Via Carignoni 51 55041 Camaiore (LU) Italy phone: +39 0584983027 fax: +39 0584983027 mob: +39 333 8128928 http://www.geo-solutions.it http://geo-solutions.blogspot.com/ http://www.linkedin.com/in/simonegiannecchini http://twitter.com/simogeo ------------------------------------------------------- On Fri, Jul 2, 2010 at 12:38 PM, Andrea Aime <aa...@opengeo.org> wrote: > Hi, > I'm looking at Daniele's last commit and wondering if it's > really an improvement as stated in the commit log > (Improved loggings using StringBuilder appends instead of String > chaining). Here is the patch: > > - if (LOGGER.isLoggable(java.util.logging.Level.FINE)) > - LOGGER.fine("Got empty intersection for > granule "+this.toString()+ " with request "+request.toString()); > + if (LOGGER.isLoggable(java.util.logging.Level.FINE)){ > + LOGGER.fine(new StringBuilder("Got empty > intersection for granule ").append(this.toString()) > + .append(" with request > ").append(request.toString()).append(" Resulting in no granule loaded: > Empty result").toString()); > + } > > Ok, hard to read pasted like that, but you get the idea, instead > of concatenating together multiple string an inline StringBuilder > is used. > > This certainly makes the code harder to read. Does it make it > faster, more scalable? > > As far as I know, it does not, the version concatenating strings > is actually exactly the same as the one using StringBuilder once > compiled. From the java.lang.String javadoc: > > ---------------------------------------------------------------- > > The Java language provides special support for the string concatenation > operator ( + ), and for conversion of other objects to strings. String > concatenation is implemented through the StringBuilder(or StringBuffer) > class and its append method. String conversions are implemented through > the method toString, defined by Object and inherited by all classes in > Java. For additional information on string concatenation and conversion, > see Gosling, Joy, and Steele, The Java Language Specification. > > ---------------------------------------------------------------- > > To prove it's actually just counter productive to use explicit > StringBuilders for direct concatenation (as opposed to string > building in a loop or over more lines of code) > I wrote this little java code: > > > public class Concatenate { > public static void main(String[] args) { > String s1 = "abc " + Math.random() + " def"; > > String s2 = new > StringBuilder("abc").append(Math.random()).append("def").toString(); > } > } > > > and then went on the command line and got a disassembly of the generated > bytecode using javap, here we go: > > > > Compiled from "Concatenate.java" > public class Concatenate extends java.lang.Object{ > public Concatenate(); > Code: > 0: aload_0 > 1: invokespecial #8; //Method java/lang/Object."<init>":()V > 4: return > > public static void main(java.lang.String[]); > Code: > 0: new #16; //class java/lang/StringBuilder > 3: dup > 4: ldc #18; //String abc > 6: invokespecial #20; //Method > java/lang/StringBuilder."<init>":(Ljava/lang/String;)V > 9: invokestatic #23; //Method java/lang/Math.random:()D > 12: invokevirtual #29; //Method > java/lang/StringBuilder.append:(D)Ljava/lang/StringBuilder; > 15: ldc #33; //String def > 17: invokevirtual #35; //Method > java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder; > 20: invokevirtual #38; //Method > java/lang/StringBuilder.toString:()Ljava/lang/String; > 23: astore_1 > 24: new #16; //class java/lang/StringBuilder > 27: dup > 28: ldc #42; //String abc > 30: invokespecial #20; //Method > java/lang/StringBuilder."<init>":(Ljava/lang/String;)V > 33: invokestatic #23; //Method java/lang/Math.random:()D > 36: invokevirtual #29; //Method > java/lang/StringBuilder.append:(D)Ljava/lang/StringBuilder; > 39: ldc #44; //String def > 41: invokevirtual #35; //Method > java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder; > 44: invokevirtual #38; //Method > java/lang/StringBuilder.toString:()Ljava/lang/String; > 47: astore_2 > 48: return > > } > > > Can anybody see a difference between the first and the second > calculation? > If there is actually none, please, let's favor readability. > > Cheers > Andrea > > -- > Andrea Aime > OpenGeo - http://opengeo.org > Expert service straight from the developers. > > ------------------------------------------------------------------------------ > This SF.net email is sponsored by Sprint > What will you do first with EVO, the first 4G phone? > Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first > _______________________________________________ > Geotools-devel mailing list > Geotools-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/geotools-devel > ------------------------------------------------------------------------------ This SF.net email is sponsored by Sprint What will you do first with EVO, the first 4G phone? 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