I have a SimpleListProperty<T>, how can I do a when (t) { is T -> todo() } how to extract the Type contained in the list property?

Where are you trying to write this

when

? Could you give a bit more context? How do you get the instance of

SimpleListProperty<T>

and what is

t

here? In general, if this class itself doesn't give access to the class of

T

, you can't. It is erased, so at runtime all you see is

SimpleListProperty

, not

SimpleListProperty<String>

. However, depending on how/where you want to use this information, using

reified

types may enable you to still get the information.

fun <T: Entity<T>> createLog(
    filename: String,
    logType: LogType,
    entityList: SimpleListProperty<T>,
    projectNum: SimpleStringProperty,
    projectName: SimpleStringProperty

I pass it to the function, T is an Entity<T> from ktorm, they are database entires.