Is 'integer + ""' a good way to convert a integer to string in Java?

Question

I always use String.valueOf(integer) to convert an integer to a string, but I saw someone to do it by integer + "". For example,

int i = 0;
String i0 = i + "";

So, is that a good way to convert integer to string?

score 13 · Answer 1 · answered Oct 14 '15 at 08:31

13

Though it works, i + "" is kind of hack to convert int to String. The + operator on string never designed to use that way. Always use String.valueOf()

answered Oct 14 '15 at 08:31

Suresh Atta

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Nice answer. Also, I think String.valueOf() is cleaner. – A1ternat1ve Oct 14 '15 at 08:43
If the `+` operator was not designed to be used that way, you would not be able to do things like `System.out.println("i=" + i)`. That would be like programming in Modula 2 again. – Thorbjørn Ravn Andersen Oct 14 '15 at 08:48
@ThorbjørnRavnAndersen Agreed, but again you are free to do that and it works absolutely. But I'm just saying that it's kind of misusing it for sake. Just suggested a cleaner way :) – Suresh Atta Oct 14 '15 at 08:53
Then you cannot say "never designed to be used that way", as it is very clear from the JLS that it is deliberate. – Thorbjørn Ravn Andersen Oct 17 '15 at 22:08
@sᴜʀᴇsʜᴀᴛᴛᴀ, what is the purpose of `+` operator for Strings?? – Anil Dec 22 '15 at 09:10

score 9 · Accepted Answer · answered Oct 14 '15 at 08:31

9

Use whatever method is more readable. String.valueOf(i) or Integer.toString(i) make your intent much clearer than i + "".

answered Oct 14 '15 at 08:31

Eran

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Is `String.valueOf` more efficient than `i + ""`? – Sayakiss Oct 14 '15 at 09:43
@Sayakiss There shouldn't be a difference performance wise (in any decent compiler). You should only worry about readability. – Eran Oct 14 '15 at 09:45

score 3 · Answer 3 · answered Oct 14 '15 at 08:36

It's not only the optimization. I don't like

"" + i

because it does not express what I really want to do.

I don't want to append an integer to an (empty) string. I want to convert an integer to string:

Integer.toString(i)

Or, not my prefered, but still better than concatenation, get a string representation of an object (integer

String.valueOf(i)

N.B: For code that is called very often, like in loops, optimization sure is also a point for not using concatenation.

score 3 · Answer 4 · answered Oct 14 '15 at 08:40

The thing there is that if you have an Integer i (non-primitive) and use i + "", you may end up with a non-null string of "null" value if i is null, while String.valueOf(...) will throw NullPointerException in this case.

In all other cases it's the same (also very similar as for the internal process that will be invoked to return the result). Given what's above, it all depends on the context that you use it for, e.x. if you plan to convert the string back to int/Integer the + case, may be more problematic.

Is 'integer + ""' a good way to convert a integer to string in Java?

4 Answers4