types/kotools.types.collection/NotEmptyList/Companion/create

create

@ExperimentalSince(version = KotoolsTypesVersion.V4_5_0)

fun <E> create(collection: Collection<E>): NotEmptyList<E>

Creates a NotEmptyList containing all the elements of the specified collection, or throws an IllegalArgumentException if the collection is empty.

Calling from Kotlin

Here's an example of calling this method from Kotlin code:

val collection: Collection<Int> = listOf(1, 2, 3)
val isSuccess: Boolean = try {
    NotEmptyList.create(collection)
    true
} catch (exception: IllegalArgumentException) {
    false
}
assertTrue(isSuccess)

The NotEmptyList type being an inline value class, this method is not available yet for Java users.

Please note that changes made to the original collection will not be reflected on the resulting NotEmptyList.

val original: MutableCollection<Int> = mutableListOf(1, 2, 3)
val notEmptyList: NotEmptyList<Int> = NotEmptyList.create(original)
assertEquals(expected = "$original", actual = "$notEmptyList")
original.clear()
assertNotEquals(illegal = "$original", actual = "$notEmptyList")

You can use the NotEmptyList.Companion.createOrNull method for returning null instead of throwing an exception in case of invalid collection.