如何更改showDatePicker输入格式颤动

import 'package:flutter/material.dart';
import 'package:intl/intl.dart';

Future<DateTime?> _selectDate(BuildContext context) async {
  final DateTime? picked = await showDatePicker(
    context: context,
    initialDate: DateTime.now(),
    firstDate: DateTime(1900),
    lastDate: DateTime(2100),
    locale: Locale("zh", "CN"), // 设置日期选择器的语言为中文
  );
  return picked;
}

RaisedButton(
  onPressed: () {
    _selectDate(context).then((DateTime? picked) {
      if (picked != null) {
        String formattedDate = DateFormat('yyyy-MM-dd').format(picked);
        print(formattedDate); // 打印选择的日期
      }
    });
  },
  child: Text('选择日期'),
),