StringBuilder vs String concatenation in toString() in Java

http://stackoverflow.com/questions/1532461/stringbuilder-vs-string-concatenation-in-tostring-in-java

 

Question

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Given the 2 toString() implementations below, which is prefered

public String toString(){    return "{a:"+ a + ", b:" + b + ", c: " + c +"}";}

or

public String toString(){    StringBuilder sb = new StringBuilder(100);    return sb.append("{a:").append(a)          .append(", b:").append(b)          .append(", c:").append(c)          .append("}")          .toString();}

More importantly given we have only 3 properties it might not make a difference, but at what point do you switch from concat to builder?

Answer: ===========================================================

Version 1 is preferable because it is shorter and the compiler will in fact turn it into version 2 - no performance difference whatsoever.

More importantly given we have only 3 properties it might not make a difference, but at what point do you switch from concat to builder?

At the point where you're concatenating in a loop - that's usually when the compiler can't substitute StringBuilder by itself.