toString but only if not null

Question

Is there any utility available to easily get the string representation of an arbitrary object if it exists and keep it null if it was null?

For example

String result = null;
if (object != null) {
    result = object.toString();
}

but less verbose.

I have looked into ObjectUtils and String.valueOf but neither returns just null itself. Both return default strings, i.e. the empty string or the string "null" instead of just null.

You could just... use the string itself without any util? What are you trying to achieve? — David Conrad, Jan 14 '20 at 21:44
Sure, but doing a ternary is a lot of code bloat. I thought there would be something in commons akin to `object == null? null : object.toString()` guess I was wrong? — awgtek, Jan 14 '20 at 21:46
@Compass That ternary is a slower way to write `return string;` — Elliott Frisch, Jan 14 '20 at 21:46
guess I wasn't clear, it's not necessarily a string, it's any object... — awgtek, Jan 14 '20 at 21:47
You should change the title, which says "... if a **String** is null..." — David Conrad, Jan 14 '20 at 21:49
The question is neither clear nor is there any use for others. As the comments show it is more than trivial. — SkateScout, Jan 14 '20 at 21:49
I agree, but I was surprised something so common wasn't placed in, well, Commons... — awgtek, Jan 14 '20 at 21:53
Well, it is. `Objects` is an utility class for pretty much the most common stuff regarding arbitrary objects. And, as shown, it has the utility you want. If that is not enough, you can always create your own helper method. — Zabuzard, Jan 14 '20 at 21:54

NoDataFound · Accepted Answer · 2020-01-14T21:51:49.733

24

If I understand your problem, you can use that (java.util.Objects is here since JDK7):

Objects.toString(s, null); // return null if s is null, s.toString() otherwise

In fact, it works for every object.

edited Jan 14 '20 at 21:51

answered Jan 14 '20 at 21:48

NoDataFound

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`StringUtils.defaultString(s)` won't work, because it converts the value to an empty string, what I need is it to be null. – awgtek Jan 14 '20 at 21:50
1

I think then `Objects.toString(o, null)` is the only option. Would have liked to avoid the extra param though. – awgtek Jan 14 '20 at 21:51
1

You're right, but Objects.toString will more than likely work. – NoDataFound Jan 14 '20 at 21:52
An upside of the extra param is that it makes it clear to readers that you're intentionally handling null, and purposefully returning `null` as the result when the value is null. A lot of times null handling behavior is accidental and a source of bugs, so by using this approach, it's clear that you as the code writer (probably) thought through the null implications and chose that behavior. – M. Justin May 17 '21 at 15:33

toString but only if not null

1 Answers1