[英]Kotlin - How to update particular value from a list of data class
我有一個 Worker 數據類,
data class Worker(val id: Int, val name:String, val gender :String, val age :Int, val tel:String,val email:String)
和工人名單
List<Worker> = listOf(workerA, workerB)
我想寫一個函數來更新 Worker 的數據,例如:
updateWorkerData(1, age, 28)
//'type' refer to name, gender, age ..
//'value' refer AA, Female, 27 ..
fun updateWorkerData(id: Int, type: Any, value: Any) {
val workers = getListOfWorker()
workers.forEach {
if (it.id == id) {
//here is where I stuck
}
}
}
我被困在如何將類型引用到數據類 Worker 中的值。 需要一些關於如何更新 Worker 數據的指南。 謝謝。
您的數據類應該具有可變屬性,以便可以更改它們:
data class Worker(val id: Int, var name: String, var gender: String, var age: Int, var tel: String, var email: String)
然后您可以將 KProperty 傳遞給可以更改該屬性的函數:
fun <T> updateWorkerData(id: Int, property: KMutableProperty1<Worker, T>, value: T) {
val workers = getListOfWorker()
workers.forEach {
if (it.id == id) {
property.set(it, value)
}
}
}
updateWorkerData(1, Worker::age, 28)
Animesh的回答是正確的,我只是想指出使用Map
of Workers(其中key是worker ID)可能更簡單,直接編輯workers,而不是做聰明(並且難以理解)的事情帶反射:
val workers: Map<Int, Worker> = listOf(
Worker(1, "a", "a", 1, "a", "a"),
Worker(2, "b", "b", 2, "b", "b"),
Worker(3, "c", "c", 3, "c", "c"),
).map { it.id to it }.toMap()
// Worker 1 changes name
workers.getValue(1).name = "Slartibartfast"
// Worker 2 gets older
workers.getValue(2).age += 1
// Worker 3 changes email
workers.getValue(3).email = "newemail@example.com"
我更喜歡使用不變性而不是對數據類使用可變字段。
一個簡單的解決方案如下:
fun List<Worker>.updateWorkerDataAge(id: Int, age: Int): List<Worker> =
this.map { worker -> if (worker.id == id) worker.copy(age = age) else worker }
你可以使用它:
val newWorkerList = workerList.updateWorkerDataAge(2, 99)
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.