defining container with generics type, it doesn't require type cast.

container_generics.kt

//ジェネリクス
//どのような型でも受け取るコンテナ
class Container<T>(val value: T)

//どのような型でも受け取る関数
fun <T> packer(value: T): Container<T>{
    return Container(value)
}

//コンテナの中身を確認する
//out Anyで変位指定を解除→あらゆる代入を許可
fun officer(containers: List<Container<out Any>>){
    for(item in containers){
        println("value = ${item.value}")
    }        
}

fun main() {
    val intContainer = Container(100)
    val strContainer = Container("hello")
    
    //キャスト不要
    val i: Int = intContainer.value
    val s: String = strContainer.value
    
    println("i = ${i}")
    println("s = ${s.uppercase()}")

    //out Anyで変位指定を解除→あらゆる代入を許可
    var containers: List<Container<out Any>> = emptyList()
    
    containers += packer(100)
    containers += packer("amazon")
    containers += packer(false)
    
    officer(containers)
}