Question

我有一个变体列表，其中每个变体都有颜色列表。我想检查每个变体是否具有过滤器的颜色，如果没有，我想从变体列表中删除该变体。当我尝试删除时出现错误：java.util.ConcurrentModificationException 这是我尝试过的：

list.map { variant ->
    variant.variantColors.map { color ->
        if (color != filterModel.color) {
            list.removeIf { color != filterModel.color }
        }
    }
}

和：

list.map { variant ->
    variant.variantColors.map { color ->
        if (color != filterModel.color) {
            list.removeAll { color != filterModel.color }
        }
    }
}

和：

val iterator = list.iterator()
while (iterator.hasNext()) {
    val item = iterator.next()
    val iteratorSec = item.variantColors.iterator()
    while (iteratorSec.hasNext()) {
        val itema = iteratorSec.next()
        if (itema != filterModel.color)
            iterator.remove()
    }
}

Answer 1

使用列表过滤器功能这样的概念

 fun main()
 {
  val myList : MutableList<ColorInfo> = mutableListOf(
    ColorInfo(color = "red",colorcode = "1111"),
    ColorInfo(color = "green",colorcode = "1123"),
    ColorInfo(color = "yellow",colorcode = "1134")
)


val filteredList = myList.filter { !it.color.equals("red") }
println(filteredList.toString())
 //out put is [Event(color=green, colorcode=1123), Event(color=yellow, colorcode=1134)]
}

data class ColorInfo(var color : String,var colorcode : String)

Answer 2

发生这种情况是因为您尝试在map()回调中对列表进行更改时对列表进行迭代。为了避免这种情况，您应该先调用removeAll（）/ removeIf（）：

class Variant(val colors: List<Int>)

fun main() {
    val badColor = 2
    val variants = mutableListOf(
            Variant(listOf(1, 2, 3)),
            Variant(listOf(2, 4, 6)),
            Variant(listOf(3, 5, 7)))
    // try removeAll()
    variants.removeAll {
        it in variants.filter {variant ->
            badColor in variant.colors
        }
    }
    //  or removeIf()
    variants.removeIf {
        badColor in it.colors
    }

    print(variants)
}

尝试从android

2 个答案: