What is the better approach to convert primitive data type into String

Question

I can convert an integer into string using

String s = \"\" + 4; // correct, but poor style
or
String u = Integer.toString(4); // this is good

I

Answer 1

String s = "" + 4;

Is compiled to this code:

StringBuffer _$_helper = new StringBuffer("");
_$_helper.append(Integer.toString(4));
String s = _$_helper.toString();

Obviously that is pretty wastefull. Keep in mind that behind the scene the compiler is always using StringBuffers if you use + in asociation with String's