+0 (this is only for error cases as far as i saw and a few concatenations so you don't see the diff in practise + the compiler is able to optimize it and even replace string builder when relevant these days)
Romain Manni-Bucau @rmannibucau <https://twitter.com/rmannibucau> | Blog <https://rmannibucau.metawerx.net/> | Old Blog <http://rmannibucau.wordpress.com> | Github <https://github.com/rmannibucau> | LinkedIn <https://www.linkedin.com/in/rmannibucau> | Book <https://www.packtpub.com/application-development/java-ee-8-high-performance> Le lun. 26 nov. 2018 à 15:38, Daniel Cunha <daniels...@apache.org> a écrit : > Wowww! > > Nice catch Otávio! > That is really a good improvement! > > Em seg, 26 de nov de 2018 às 10:47, Otávio Gonçalves de Santana < > osant...@tomitribe.com> escreveu: > > > The reason to prefer StringBuilder is that both + and concat create a new > > object every time you call them (provided the right-hand side argument is > > not empty). This can quickly add up to a lot of objects, almost all of > > which are completely unnecessary. > > > > public class Main{ > > public static void main(String[] args) > > { > > long now = System.currentTimeMillis(); > > slow(); > > System.out.println("slow elapsed " + > > (System.currentTimeMillis() - now) + " ms"); > > > > now = System.currentTimeMillis(); > > fast(); > > System.out.println("fast elapsed " + > > (System.currentTimeMillis() - now) + " ms"); > > } > > > > private static void fast() > > { > > StringBuilder s = new StringBuilder(); > > for(int i=0;i<100000;i++) > > s.append("*"); > > } > > > > private static void slow() > > { > > String s = ""; > > for(int i=0;i<100000;i++) > > s+="*"; > > } > > } > > > > > > - slow elapsed 11741 ms > > - fast elapsed 7 ms > > > > Also, this PR avoids unnecessary call in StringBuilder > > Ref: https://github.com/apache/tomee/pull/219 > > > > > -- > Daniel "soro" Cunha > https://twitter.com/dvlc_ >
