返回出现字母的字符串的总和-使用streams

import java.util.stream.IntStream;

public class Main {
    public static void main(String[] args) {
        String input = "abc123def456";
        int sum = calculateAlphabetSum(input);
        System.out.println("出现字母的字符串的总和为：" + sum);
    }

    public static int calculateAlphabetSum(String input) {
        return input.chars()
                .filter(Character::isLetter)
                .map(Character::toLowerCase)
                .map(c -> c - 'a' + 1)
                .sum();
    }
}