String conversions

Question

I have a method which takes String argument.In some cases i want to pass int value to that method.For invoking that method i want to convert int into String.For that i am doing the following

    aMethod(""+100);

One more option is

    aMethod(String.valueOf(100));

Both are correct.I don't know which is appropriate?Which gives better performance?

Mostly this is happen in GWT.In GWT for setting size of panels and widgets i want to do this.

Can anyone give suggestion?

Answer 1

Using + on strings creates multiple string instances, so using valueOf is probably a bit more performant.

Answer 2

Good article by Jon Skeet about your question's topic: String conversions - the Good, the Okay-I-Suppose, and the Utterly Horrible

Answer 3

Normally you'd use Integer.toString(int) or String.valueOf(int). They both return the same thing, and probably have identical implementations. Integer.toString(int) is a little easier to read at a glance though, IMO.

Answer 4

I'd assume that this:

aMethod(""+100);

turns into this by the compiler:

aMethod(new StringBuilder("").append(String.valueOf(100)).toString());

So the option of calling the String.valueOf directly is probably the better choice. You could always compile them and compare the bytecode to see for sure.

Answer 5

Since you're mostly using it in GWT, I'd go with the ""+ method, since it's the neatest looking, and it's going to end up converted to javascript anyway, where there is no such thing as a StringBuilder.

Please don't hurt me Skeet Fanboys ;)