Populate a list in Kotlin with a for loop

Question

It's been a while that I just started to learn how to develop in Kotlin. There is this thing that I am working on, I am trying to parse a list into another type of list. Basically they are the same thing but with different names. But when I try to populate the new list with the data that I get from the list given as parameter in the function the list only gets populated with the first object.

Here is my function:

fun convertRoomClass(course: List<Course>) : List<Courses> {

    lateinit var list : List<Courses>


    course.forEach {
        val id = it.pathID
        val name = it.pathName
        val desc = it.pathDescription

        val crs : Courses = Courses(id, name!!, desc!!)

         list = listOf(crs)
    }

    return list
}

Answer 1

The error in your code is that you are making a list in every iteration of the loop. You should make the list first and then add every item from the loop to it!

fun convertRoomClass(courses: List<Course>) : List<AnotherCourseClass> {
    val newList = mutableListOf<AnotherCourseClass>()
    courses.forEach {
        newList += AnotherCourseClass(it.pathID, it.pathName, it.pathDescription)
    }
    return newList
}

A better solution is to use the map function

fun convertRoomClass(courses: List<Course>) = courses.map {
   AnotherCourseClass(it.pathID, it. pathName, it.pathDescription)
}

Answer 2

You might be looking for Kotlin Map

Example:

course.map { Courses(it.pathID, it.pathName,it.pathDescription) }