How do I convert from int to String?

Question

I\'m working on a project where all conversions from int to String are done like this:

int i = 5;
String strI = \"\" + i;
         


        

Answer 1

This technique was taught in an undergraduate level introduction-to-Java class I took over a decade ago. However, I should note that, IIRC, we hadn't yet gotten to the String and Integer class methods.

The technique is simple and quick to type. If all I'm doing is printing something, I'll use it (for example, System.out.println("" + i);. However, I think it's not the best way to do a conversion, as it takes a second of thought to realize what's going on when it's being used this way. Also, if performance is a concern, it seems slower (more below, as well as in other answers).

Personally, I prefer Integer.toString(), as it is obvious what's happening. String.valueOf() would be my second choice, as it seems to be confusing (witness the comments after darioo's answer).

Just for grins :) I wrote up classes to test the three techniques: "" + i, Integer.toString, and String.ValueOf. Each test just converted the ints from 1 to 10000 to Strings. I then ran each through the Linux time command five times. Integer.toString() was slightly faster than String.valueOf() once, they tied three times, and String.valueOf() was faster once; however, the difference was never more than a couple of milliseconds.

The "" + i technique was slower than both on every test except one, when it was 1 millisecond faster than Integer.toString() and 1 millisecond slower than String.valueOf() (obviously on the same test where String.valueOf() was faster than Integer.toString()). While it was usually only a couple milliseconds slower, there was one test where it was about 50 milliseconds slower. YMMV.