统计文件中的字符个数（Kotlin）

代码：

import java.io.File

/**
 * Created by FangJu on 2020/1/28
 * 统计文件中字符个数
 */
fun main() {
    File("build.gradle").readText() //读取字符串
        .toCharArray()  // 转换为字符数组
        .filter {
            !it.isWhitespace()  //过滤空格
        }
        .groupBy {
            it  // 按照单个“char”分组
        }.map {
            it.key to it.value.size     //转换成Pair
        }.let {
            println(it.toString())
        }
}

结果：

[(p, 13), (l, 16), (u, 6), (g, 8), (i, 31), (n, 24), (s, 15), ({, 5), (d, 6), (', 16), (j, 9), (a, 12), (v, 8), (o, 25), (r, 16), (., 15), (e, 26), (t, 25), (b, 4), (k, 6), (m, 12), (1, 7), (3, 1), (6, 1), (}, 5), (x, 1), (0, 1), (-, 3), (S, 2), (N, 1), (A, 1), (P, 1), (H, 1), (O, 3), (T, 4), (c, 4), (C, 3), (y, 1), (=, 3), (8, 4), ((, 1), (), 1), (", 6), (:, 4), (,, 2), (4, 1), (2, 1), (K, 2)]