How to filter a list by its item member variable m...

# announcements

[Simon Lin]

How to filter a list by its item member variable must not null and map its member?

for example:

data class Foo(val id: String? = null)

val list = listOf(Foo("0"), Foo(), Foo("2"))

// I would like to get ["0", "2"]
// I use this, but I don't like the Double !! 
list.filter { it.id != null }
    .map { it.id!! }