Just wanted to see if anyone knows of an idiomatic way of adding a `,` between strings in a string b...

# getting-started

[Colton Idle]

Just wanted to see if anyone knows of an idiomatic way of adding a , between strings in a string builder.
I know joinToString exists and it works great for arrays, but I basically want the same functionality for a string builder.

Here's what I'm currently doing (no commas yet):

topic.data.forEach {
                    myBuilder.append("${it.city} ${it.status}")
                }
            }

Maybe I'm missing something basic. Thanks

[Vampire]

Is using a StringBuilder a fixed necessity?
If not you could for example do
topic.data.joinToString(',') { "${it.city} ${it.status}" }

[nanodeath]

IIRC you can also pass a StringBuilder to joinTo

https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/join-to.html

[Vampire]

Ah, yes, you are right, StringBuilder is Appendable.
So then it would be topic.data.joinTo(myBuilder, ",") { "${it.city} ${it.status}" }.

[Colton Idle]

@nanodeath Hm. But I would need to make an empty array first and then call myEmptyArray.joinTo(myStringBuilder, ...).

[Colton Idle]

Oh. I could use the topic.data directly. 🤦

[nanodeath]

I don't love that the city + status string generation is itself likely using a string builder, but I don't think there's much you can do about that without like...building up an arraylist by hand, and that's just not worth it.

[Colton Idle]

@Vampire string builder isn't a fixed necessity. I guess I can just use your join to string suggesstion to.

It's just muscle memory to use string builder when building strings. 😄

I'm sure it's a micro optimization now, but I wonder if there's any difference.

[nanodeath]

readability wise, probably

[Colton Idle]

Anyone have any preference/idiomatic thoughts on

topic.data.joinToString(',') { "${it.city} ${it.status}" }

vs

topic.data.joinTo(myBuilder, ",") { "${it.city} ${it.status}" }

[Vampire]

Bad muscle memory then, should have StringJoiner in it 😄

[Vampire]

first one imho

[nanodeath]

I'd use joinToString if you don't already have and need a builder

[Colton Idle]

Thanks everyone. Appreciate your time and experience.