[英]Change a value in mutable list in Kotlin
我得到了这个可变列表:
[Videos(id=4, yt_id=yRPUkDjwr1A, title=test4, likes=0, kat=pranks, ilike=false), Videos(id=3, yt_id=WkyUU9ZDUto, title=test3, likes=0, kat=pranks, ilike=false), Videos(id=2, yt_id=B_X9OQqtduE, title=test2, likes=0, kat=animals, ilike=false), Videos(id=1, yt_id=ywaKlGNiv80, title=test1, likes=0, kat=animals, ilike=false)]
我如何将ilike
更改为true
,其中id
为2
这是我尝试过的:
for (i in 0 until vids!!.size) {
Log.d("lets", vids!!.get(i).title)
if(vids!!.get(i).id == 2){
vids!!.get(i).ilike = true
}
}
如果您预计很少有项目(可能是 1 项或 2 项?)受到影响,
您可以filter
列表,然后更改过滤项目的iLike
:
vids!!.filter { it.id == 2 }.forEach { it.iLike = true }
试试这个,我假设你的Videos
结构是一个有点像这样定义的数据类。 data class Videos(val id: Int, val yt_id: String, val title: String, val likes: Int, val kat: String, val ilike: Boolean)
list.forEachIndexed { index, video ->
video.takeIf { it.id == 2}?.let {
list[index] = it.copy(ilike = true)
}
}
我必须更改几个属性,并且需要保存更改后的对象。 因此,以下方法对我更有效:
//First, find the position of the video in the list
val videoPosition= list.indexOfFirst {
it.id == 2
}
//Now get your video by position and make changes
val updatedVideo = list[videoPosition].apply {
//Make all changes you need here
ilike = true
//...
}
//Finally, replace updated video into your list.
list[videoPosition] = updatedVideo
如果不想使用predicates
或iteration
请使用set
替换对象
例如。
val video = (...,read = true) //or however you are getting the current model
val updatedVideo = video
updatedVideo.read = true
vids[vids.indexOf(video)] = updatedVideo
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