Kotlin中两类字符串列表排序问题求助：基于首个列表值排序双列表、按周一至周日顺序排序日期字符串列表

Got it, let's tackle these two Kotlin sorting problems one by one!

1. Sort Two String Lists Based on the Order of the First List #

I’ll cover two common scenarios for this requirement, since the exact use case can vary a bit:

Scenario 1: Keep elements paired while sorting the first list #

If your two lists have one-to-one corresponding elements (e.g., list1 holds labels and list2 holds matching data), you can pair them up, sort by the first list’s values, then split back into separate lists:

fun main() {
    val labels = mutableListOf("b", "a", "c")
    val values = mutableListOf("2", "1", "3")

    // Pair elements from both lists to preserve their relationship
    val paired = labels.zip(values)
    
    // Sort the pairs using the first element (label) as the key
    val sortedPairs = paired.sortedBy { it.first }
    
    // Unzip back into two sorted lists
    val sortedLabels = sortedPairs.map { it.first }
    val sortedValues = sortedPairs.map { it.second }

    println("Sorted Labels: $sortedLabels") // Output: [a, b, c]
    println("Sorted Values: $sortedValues") // Output: [1, 2, 3]
}

Scenario 2: Sort using the first list as a predefined reference order #

If the first list is a fixed priority order (e.g., a custom sequence you want to enforce), use its index to sort the second list (and adjust the first list if needed):

fun main() {
    val referenceOrder = listOf("Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun")
    val scheduleItems = listOf("Sun 9am", "Mon 10am", "Wed 11am")

    // Sort scheduleItems based on their position in the referenceOrder list
    val sortedSchedule = scheduleItems.sortedBy { item ->
        // Extract the day abbreviation from the string (adjust this split logic if your format differs)
        val day = item.split(" ")[0]
        referenceOrder.indexOf(day)
    }

    println("Sorted Schedule: $sortedSchedule") // Output: [Mon 10am, Wed 11am, Sun 9am]
}

2. Sort Day-Time Strings by Monday-to-Sunday Order #

For this task, we’ll create a custom order mapping for day abbreviations, then use that to sort your list. Note: I noticed you have "Web" in your list—assuming that’s a typo for "Wed", I’ve included support for both in the code:

fun main() {
    val scheduleList = listOf(
        "Sun 11:30 am - 9:00 pm",
        "Mon 11:30 am - 9:00 pm",
        "Tue 11:30 am - 9:00 pm",
        "Web 11:30 am - 9:00 pm", // Handling typo for "Wed"
        "Thu 11:30 am - 9:00 pm",
        "Fri 11:30 am - 9:30 pm",
        "Sat 11:30 am - 9:30 pm"
    )

    // Define our desired order: Monday → Sunday
    val dayPriorityMap = mapOf(
        "Mon" to 0,
        "Tue" to 1,
        "Wed" to 2,
        "Web" to 2, // Account for the typo
        "Thu" to 3,
        "Fri" to 4,
        "Sat" to 5,
        "Sun" to 6
    )

    // Sort the list using the priority map
    val sortedSchedule = scheduleList.sortedBy { item ->
        // Grab the day abbreviation from the start of the string
        val dayAbbrev = item.split(" ")[0]
        // Assign a high value to unknown days so they land at the end
        dayPriorityMap[dayAbbrev] ?: Int.MAX_VALUE
    }

    // Print the sorted result
    sortedSchedule.forEach { println(it) }
}

Output: #

Mon 11:30 am - 9:00 pm
Tue 11:30 am - 9:00 pm
Web 11:30 am - 9:00 pm
Thu 11:30 am - 9:00 pm
Fri 11:30 am - 9:30 pm
Sat 11:30 am - 9:30 pm
Sun 11:30 am - 9:00 pm

The map assigns a numerical priority to each day, so sortedBy knows exactly how to order the items. Any unrecognized day abbreviations will get pushed to the end of the list.

内容的提问来源于stack exchange，提问作者Jack