Sort array of objects alphabetically first, and then by numbers-CodePudding

I have an array of objects (Drinks) that contains a theDrinkName field. I would like to be able to sort the Drink objects theDrinkName field alphabetically first, and then numerically.

Here's the function that I use to generate all drinks.

data class Drink(val theDrinkName:String)

object DrinkData {

    fun generateAllDrinks():Array<Drink> {
        return arrayOf(
            Drink("Vodka"),
            Drink("rum"),
            Drink("Gin"),
            Drink("151"),
            Drink("99")
        )
    }
    
}

And I sort it alphabetically (based on theDrinkName) with the following:

val allDrinks = DrinkData.generateAllDrinks().sortedBy { it.theDrinkName.toLowerCase().first()}.toTypedArray()

for (drink in allDrinks){
    println(drink.theDrinkName)
}

This prints the following:

151
99
Gin
rum
Vodka

By default it sorts numbers first, and then by letters. How do I sort this data by letters first, and then numbers, as seen below:

Desired result:

Gin
rum
Vodka
151
99

CodePudding user response：

You can sort first by the indication whether the fist char is a digit and then by the full name:

val allDrinks = DrinkData.generateAllDrinks().sortedWith(
    compareBy<Drink> { it.theDrinkName.first().isDigit() }
        .thenBy { it.theDrinkName.lowercase() }
)

CodePudding user response：

Another possible solution:
The reason you are getting numbers before the words is because alphabets have larger ASCII value than digits. You can add a space before words to lower their comparison value and use that for sorting.

DrinkData.generateAllDrinks().sortedBy { drink ->
    drink.theDrinkName.lowercase().let { if (it[0].isDigit()) it else " $it" }
}

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