Hello ! Why is it useful that toString can return ...

# stdlib

[Jamy]

Hello ! Why is it useful that toString can return a “null” string if it is applied to null? I may sound silly to you, but I didn’t know. As a result, I just passed some time looking for why val a = b?.c.toString() where b == null results a != null since in this case a == "null". So to get what I want, I have to write val a = b?.c?.toString(). It’s not a problem, I just don’t understand the purpose.

[Derek Peirce]

It may be to emulate the behavior in Java when concatenation includes a null object.

[Milan Hruban]

I find it very convenient e.g in debug logs

[bogdoll]

If I read you code correctly, it is not that toString() returns a null but that b?.<anything> returns a null.

You said that b==null, so b?. will always return null.

Try to make b!=null then if c is also not null, a should be a string IF toString() was defined to not return null.

[elizarov]

What was the code you were writing doing? What were you using toString for?

[Jamy]

In an Android application, I receive an entity from an API that has a potential link with another entity. So an optional UUID field. I store my entity with room and I convert my UUID into a string if it exists. Otherwise the field remains null.