What data type can save latest 20 values in Kotlin?

Question

Is there a data type where I can save latest 20 values in it?

Maybe just like Code A

Code A

val myData: ADateType<Int>(20)

myData.add(1)
myData.add(2)
...
myData.add(20)
myData.add(21)

val result1=myData.getList //It will return 2,3,4,...20,21

myData.add(22)
myData.add(23)

val result2=myData.getList //It will return 4,5,6...22,23

Answer 1

collection don't have custom limite, but you can write a class to control the size of collection, like this

class ADateType<E>() {
    private val mList = mutableListOf<E>()
    private val mMaxSize = 20

    fun add(element: E) {
        if (mList.size>=mMaxSize)
            mList.removeAt(0)

        mList.add(element)
    }

    fun toList(): List<E> {
        return mList.toList()
    }
}

The result is someting like this

fun main() {
    val list = ADateType<Int>()
    list.add(1)
    list.add(2)
...
    list.add(20)
    list.add(21)
    list.add(22)

    
    println(list.toList())  //It will return 3,4,5,6...21,22
}