Question

What is better

int i = 45;
String str = "dsfgdsgf"+i;

or

int i = 45;
String str = new StringBuilder().append("dsfgdsgf").append(i).toString();

I have read somewhere that StringBuilder is always better than concatenating strings

Answer 1

There is no difference in performance, as the compiler will internally convert the first version to the second one.

Since the first version is more readable you should use it when you concatenate a fixed number of items into a string.

Use StringBuilder when you append to a string many times, for example in a loop.