いいねの数などを「K」とか「M」とかで省略する拡張関数

Facebookのように「いいね!」の数を1.5Kとか10Mとか省略するための拡張関数を書きました。
ご自由にお使いください。
桁数を変えれば1.5万とかもいけると思います。

Int.kt

package com.ringored.extensions

const val K = 1_000
const val M = 1_000_000
const val B = 1_000_000_000

/*小数点第1位まで表示*/
const val ROUND_DECIMAL = 10

fun Int.toStringKMB():String{
    val numUnit:String
    var num:Double = if(this < 0){-this.toDouble()} else {this.toDouble()}
    when {
        this < K -> {
            numUnit = ""
        }
        this < M -> {
            numUnit = "K"
            num /= K
        }
        this < B -> {
            numUnit = "M"
            num /= M
        }
        else -> {
            numUnit = "B"
            num /= B
        }
    }
    num = ((Math.round(num * ROUND_DECIMAL)).toDouble()/ROUND_DECIMAL)
    return if(num % 1 == 0.0) {
        (Math.round(num) * if(this<0){-1}else{1}).toString() + numUnit
    } else {
        (num * if(this<0){-1}else{1}).toString() + numUnit
    }
}

使い方

Main.kt

val random = (0..10).random()
val magnification  = (0..100000).random()
val test = (random * magnification)
val test2 = (0..100000000).random()

Log.i(LogUtils.TAG,"before:" +test.toString() +" after:"+test.toStringKMB() )
Log.i(LogUtils.TAG,"before:" +test2.toString() +" after:"+test2.toStringKMB() )

出力結果

before:4887362 after:4.9M
before:196512 after:196.5K
before:97485003 after:97.5M
before:0 after:0
before:21898593 after:21.9M
before:67506 after:67.5K
before:54335794 after:54.3M
before:323694 after:323.7K
before:64874733 after:64.9M