英文:
Adding BigDecimal Numbers in Kotlin
问题
Here's the translation of the code section you provided:
我有以下映射，但现在我需要将百分比数据添加到列表中，以便创建公式，我需要列表中所有值的总和
data class Data(
val id: Int,
val cost: Int,
val env: String,
val item: String
)
data class TotalCost(
val item: String,
val env: String,
val cost: BigDecimal
)
val input = listOf(
Data(id = 1, cost = 0.00000000001, env = "prod", item = "Storage"),
Data(id = 2, cost = 0.00000000002, env = "qa", item = "Storage"),
Data(id = 3, cost = 0.00000000003, env = "prod", item = "Storage"),
Data(id = 4, cost = 0.00000000005, env = "qa", item = "Bandwidth"),
Data(id = 5, cost = 0.00000000002, env = "qa", item = "Bandwidth"),
Data(id = 6, cost = 0.00000000005, env = "prod", item = "Bandwidth"),
Data(id = 7, cost = 0.00000000006, env = "prod", item = "Bandwidth"),
Data(id = 8, cost = 0.00000000001, env = "prod", item = "Bandwidth"),
Data(id = 9, cost = 0.00000000005, env = "qa", item = "vm"),
Data(id = 10, cost = 0.00000000002, env = "uat", item = "vm"),
Data(id = 11, cost = 0.00000000003, env = "qa", item = "vm"),
Data(id = 12, cost = 0.00000000004, env = "prod", item = "vm"),
Data(id = 13, cost = 0.00000000005, env = "uat", item = "vm")
)
val result = input
.groupBy {
it.item to it.env
}
.map { (key, value) ->
listOf(
key.first,
key.second,
value.sumOf { it.cost.toBigDecimal() }
)
}
我正在尝试这样做;
var totalCost: BigDecimal = BigDecimal.ZERO
result.forEach { totalCostData ->
totalCost = totalCost.add(totalCostData[2].toBigDecimal())
}
并且收到以下错误消息;
未解析的引用。由于接收器类型不匹配，以下候选项都不适用:
Please note that the code you provided has HTML entities (e.g., ") which need to be replaced with their respective characters in a real Kotlin environment. This code snippet should be used as a reference, and you might need to adjust it to your specific Kotlin development environment to resolve the error.
英文:
I have the following mapping, but now I need to add percentage data to the list, so to create the formula, I need the total of all the values in the list
data class Data(
val id: Int,
val cost: Int,
val env: String,
val item: String
)
data class TotalCost(
val item: String,
val env: String,
val cost: BigDecimal
)
val input = listOf(
Data(id = 1, cost = 0.00000000001, env = "prod", item = "Storage"),
Data(id = 2, cost = 0.00000000002, env = "qa", item = "Storage"),
Data(id = 3, cost = 0.00000000003, env = "prod", item = "Storage"),
Data(id = 4, cost = 0.00000000005, env = "qa", item = "Bandwidth"),
Data(id = 5, cost = 0.00000000002, env = "qa", item = "Bandwidth"),
Data(id = 6, cost = 0.00000000005, env = "prod", item = "Bandwidth"),
Data(id = 7, cost = 0.00000000006, env = "prod", item = "Bandwidth"),
Data(id = 8, cost = 0.00000000001, env = "prod", item = "Bandwidth"),
Data(id = 9, cost = 0.00000000005, env = "qa", item = "vm"),
Data(id = 10, cost = 0.00000000002, env = "uat", item = "vm"),
Data(id = 11, cost = 0.00000000003, env = "qa", item = "vm"),
Data(id = 12, cost = 0.00000000004, env = "prod", item = "vm"),
Data(id = 13, cost = 0.00000000005, env = "uat", item = "vm")
)
val result = input
.groupBy {
it.item to it.env
}
.map { (key, value) ->
listOf(
key.first,
key.second,
value.sumOf { it.cost.toBigDecimal() }
)
}
I am trying this;
var totalCost: BigDecimal = BigDecimal.ZERO
result.forEach { totalCostData ->
totalCost = totalCost.add(totalCostData[2].toBigDecimal())
}
and getting this error message;
Unresolved reference. None of the following candidates is applicable because of receiver type mismatch:
答案1
得分: 0
问题位于这里：
listOf(
key.first,
key.second,
value.sumOf { it.cost.toBigDecimal() }
)
您需要将项目转换为3个不同的值，因此将它们存储在列表中。但是，前两个值是字符串，第三个是BigDecimal。列表只能存储相同类型的项目，因此在这种情况下它变成了List<Any>，然后totalCostData[2]就是Any（这并不完全正确）。
有两种方法可以解决这个问题。您可以将其强制转换为BigDecimal，因为我们知道它的类型：
totalCost = totalCost.add(totalCostData[2] as BigDecimal)
或者更好的做法是不使用列表，而是将结果存储在一个自定义和完全类型化的类中。事实上，看起来您已经创建了这样的类，但出于某种原因没有使用它：
TotalCost(
key.first,
key.second,
value.sumOf { it.cost.toBigDecimal() }
)
...
totalCost = totalCost.add(totalCostData.cost)
英文:
Problem is located here:
listOf(
key.first,
key.second,
value.sumOf { it.cost.toBigDecimal() }
)
You needed to transform items into 3 distinct values, so you stored them in a list. However, first two values are strings and the third is BigDecimal. List can only store items of same types, so in this case it becomes pretty much List<Any> and then totalCostData[2] is just Any (this is not exactly correct).
There are two ways to fix the problem. You can either cast it to BigDecimal as we know its type:
totalCost = totalCost.add(totalCostData[2] as BigDecimal)
Or better, do not use a list, but store results in a custom and fully typed class. As a matter of fact, it seems you already created such class, but for some reason you didn't use it:
TotalCost(
key.first,
key.second,
value.sumOf { it.cost.toBigDecimal() }
)
...
totalCost = totalCost.add(totalCostData.cost)
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