java - Is += more efficient than concat? -

this question has answer here:

• string concatenation: concat() vs “+” operator 10 answers

i've been reading code produced other developers on team, seem favor using += string concatenation, whereas prefer using .concat() feels easier read.

i'm trying prepare argument why using .concat() better, , i'm wondering, there difference in efficiency between two?

which option "should" taking?

public class stuff {      public static void main(string[] args) {          string hello = "hello ";         hello += "world";         system.out.println(hello);          string helloconcat = "hello ".concat("world");         system.out.println(helloconcat);     } } 

since string immutable in java, when +, += or concat(string), new string generated. bigger string gets longer takes - there more copy , more garbage produced.

today's java compilers optimizes string concatenation make optimal, e.g.

system.out.println("x:"+x+" y:"+y); 

compiler generates to:

system.out.println((new stringbuilder()).append("x:").append(x).append(" y:").append(y).tostring()); 

my advice write code that's easier maintain , read.

this link shows performance of stringbuilder vs stringbuffer vs string.concat - done right