如何用正确的格式从所选日期减去1个月

from datetime import datetime
from dateutil.relativedelta import relativedelta

# 假设所选日期为 '2023-10-15'
selected_date = datetime.strptime('2023-10-15', '%Y-%m-%d')

# 减去一个月
new_date = selected_date - relativedelta(months=1)

print(new_date.strftime('%Y-%m-%d'))  # 输出: 2023-09-15

// 假设所选日期为 '2023-10-15'
let selectedDate = new Date('2023-10-15');

// 使用 moment.js 减去一个月
let newDate = moment(selectedDate).subtract(1, 'months').toDate();

console.log(newDate.toISOString().split('T')[0]);  // 输出: 2023-09-15

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;

public class Main {
    public static void main(String[] args) {
        // 假设所选日期为 '2023-10-15'
        LocalDate selectedDate = LocalDate.parse("2023-10-15", DateTimeFormatter.ISO_LOCAL_DATE);

        // 减去一个月
        LocalDate newDate = selectedDate.minusMonths(1);

        System.out.println(newDate.format(DateTimeFormatter.ISO_LOCAL_DATE));  // 输出: 2023-09-15
    }
}