Please tell me how in such a data structure (simplified for better understanding) to bring all the children of the entity into one list:
fun main() {
val listOfEntities = listOf(
Entity(
name = "John",
entities = listOf(
Entity(
name = "Adam",
entities = listOf()
),
Entity(
name = "Ivan",
entities = listOf(
Entity(
name = "Henry",
entities = listOf(
Entity(
name = "Kate",
entities = listOf(
Entity(
name = "Bob",
entities = listOf()
)
)
)
)
)
)
)
)
)
)
val result = listOfEntities.flatMap { it.entities }.map { it.name }
println(result)
}
data class Entity(
val name: String,
val entities: List<Entity>
)
I expect to see following result:
[John, Adam, Ivan, Henry, Kate, Bob]
I try to use flatMap, but it did not lead to the expected result.
Thank you in advance!
You can traverse the tree of Entities recursively like this:
fun List<Entity>.flattenEntities(): List<Entity> =
this + flatMap { it.entities.flattenEntities() }
Then you can call
val result = listOfEntities.flattenEntities().map { it.name }
to obtain the desired result.
You could do it like this
fun List<Entity>.flatten(): List<String> {
return flatMap { listOf(it.name) + it.entities.flatten()}
}
and then
val result = listOfEntities.flatten()