replace

class Solution {
    public long solution(String numbers) {
        String string_num = numbers
            .replace("zero", "0")
            .replace("one", "1")
            .replace("two", "2") 
            .replace("three", "3")
            .replace("four", "4")
            .replace("five", "5")
            .replace("six", "6")
            .replace("seven", "7")
            .replace("eight", "8")
            .replace("nine", "9");

        long answer = Long.parseLong(string_num);
        return answer;
    }
}