Sorting Strings that contains number in kotlin

Question

I wanna sort some strings that contain numbers but after a sort, it becomes like this ["s1", "s10", "s11", ... ,"s2", "s21", "s22"]. after i search i fount this question with same problem. but in my example, I have mutableList<myModel>, and I must put all string in myModel.title for example into a mutable list and place into under code:

   val sortData = reversedData.sortedBy {
          //pattern.matcher(it.title).matches()
             Collections.sort(it.title, object : Comparator<String> {
                override fun compare(o1: String, o2: String): Int {
                    return extractInt(o1) - extractInt(o2)
                }

                 fun extractInt(s: String): Int {
                     val num = s.replace("\\D".toRegex(), "")
                     // return 0 if no digits found
                     return if (num.isEmpty()) 0 else Integer.parseInt(num)
                 }
            })
        }

I have an error in .sortedBy and Collections.sort(it.title), may please help me to fix this.

at first, I must find a way to convert it.title to mutable list. because Collections.sort need that. I don't know how to push all it.title from a model into a mutable list and then I think I must use return before Collections.sort for fixing .sortedBy — Mehrdad Dolatkhah, Dec 10 '18 at 11:59
don't mix `Collections.sort` and `sortedBy`. You may want to have a look at `sortWith` instead.... also: `sortedBy` and `sortedWith` are similar (they return a new list), whereas `sortWith` operates on the current list... — Roland, Dec 10 '18 at 12:32
how can the accepted answer be **the** answer to your problem? it is way too complicated than any other answer, it uses `Observable`/`Subscriber`, something you didn't... — Roland, Dec 11 '18 at 15:19

hakim · Answer 1 · 2018-12-10T12:53:05.323

8

you can use sortWith instead of sortBy for example:

class Test(val title:String) {
  override fun toString(): String {
    return "$title"
  }
}

val list = listOf<Test>(Test("s1"), Test("s101"),
Test("s131"), Test("s321"), Test("s23"), Test("s21"), Test("s22"))
val sortData = list.sortedWith( object : Comparator<Test> {
override fun compare(o1: Test, o2: Test): Int {
    return extractInt(o1) - extractInt(o2)
}

fun extractInt(s: Test): Int {
    val num = s.title.replace("\\D".toRegex(), "")
    // return 0 if no digits found
    return if (num.isEmpty()) 0 else Integer.parseInt(num)
}

})

will give output: [s1, s21, s22, s23, s101, s131, s321]

edited Dec 10 '18 at 12:53

answered Dec 10 '18 at 11:56

hakim

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how I must push all it.title into a list and use in sortData ? – Mehrdad Dolatkhah Dec 10 '18 at 12:15
@MehrdadDolatkhah I update my sample, hopefully it can give you the idea how to solve your problem, how to access title (attribute). change class `Test` with your `MyModel` class – hakim Dec 10 '18 at 12:53

score 4 · Answer 2 · answered Dec 10 '18 at 11:55

4

A possible solution based on the data you posted:

sortedBy { "s(\\d+)".toRegex().matchEntire(it)?.groups?.get(1)?.value?.toInt() }

Of course I would move the regex out of the lambda, but it is a more concise answer this way.

answered Dec 10 '18 at 11:55

m0skit0

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Roland · Answer 3 · 2018-12-10T12:17:53.333

As you state that you need a MutableList, but don't have one yet, you should use sortedBy or sortedWith (in case you want to work with a comparator) instead and you get just a (new) list out of your current one, e.g.:

val yourMutableSortedList = reversedData.sortedBy {
  pattern.find(it)?.value?.toInt() ?: 0
}.toMutableList() // now calling toMutableList only because you said you require one... so why don't just sorting it into a new list and returning a mutable list afterwards?

You may want to take advantage of compareBy (or Javas Comparator.comparing) for sortedWith.

If you just want to sort an existing mutable list use sortWith (or Collections.sort):

reversedData.sortWith(compareBy {
  pattern.find(it)?.value?.toInt() ?: 0
})

// or using Java imports:
Collections.sort(reversedData, Compatarator.comparingInt {
  pattern.find(it)?.value?.toInt() ?: 0 // what would be the default for non-matching ones?
})

Of course you can also play around with other comparator helpers (e.g. mixing nulls last, or similar), e.g.:

reversedData.sortWith(nullsLast(compareBy {
  pattern.find(it)?.value
}))

For the samples above I used the following Regex:

val pattern = """\d+""".toRegex()

score 2 · Accepted Answer · answered Dec 11 '18 at 05:50

A possible solution can be this:

  reversedData.toObservable()
                    .sorted { o1, o2 ->
                        val pattern = Pattern.compile("\\d+")
                        val matcher = pattern.matcher(o1.title)
                        val matcher2 = pattern.matcher(o2.title)

                        if (matcher.find()) {
                            matcher2.find()
                            val o1Num = matcher.group(0).toInt()
                            val o2Num = matcher2.group(0).toInt()

                            return@sorted o1Num - o2Num
                        } else {
                            return@sorted o1.title?.compareTo(o2.title ?: "") ?: 0
                        }
                    }
                    .toList()
                    .subscribeBy(
                        onError = {
                            it
                        },
                        onSuccess = {
                            reversedData = it
                        }
                    )

Use Kotlin's regex extensions, they're shorter and simpler. Check my answer for an example. — m0skit0, Dec 26 '18 at 11:12

score -1 · Answer 5 · answered Apr 11 '19 at 04:53

I wrote a custom comparator for my JSON sorting. It can be adapted from bare String/Number/Null

fun getComparator(sortBy: String, desc: Boolean = false): Comparator<SearchResource.SearchResult> {
    return Comparator { o1, o2 ->
        val v1 = getCompValue(o1, sortBy)
        val v2 = getCompValue(o2, sortBy)

        (if (v1 is Float && v2 is Float) {
            v1 - v2
        } else if (v1 is String && v2 is String) {
            v1.compareTo(v2).toFloat()
        } else {
            getCompDefault(v1) - getCompDefault(v2)
        }).sign.toInt() * (if (desc) -1 else 1)
    }
}

private fun getCompValue(o: SearchResource.SearchResult, sortBy: String): Any? {
    val sorter = gson.fromJson<JsonObject>(gson.toJson(o))[sortBy]
    try {
        return sorter.asFloat
    } catch (e: ClassCastException) {
        try {
            return sorter.asString
        } catch (e: ClassCastException) {
            return null
        }
    }
}

private fun getCompDefault(v: Any?): Float {
    return if (v is Float) v else if (v is String) Float.POSITIVE_INFINITY else Float.NEGATIVE_INFINITY
}

So adapt your comparator and share adapted version please. – Yazon2006 Aug 12 '20 at 19:44 — Yazon2006, Aug 12 '20 at 19:44

Sorting Strings that contains number in kotlin

5 Answers5