how to make circular container flutter code example

Example 1: flutter circular container

Container(
  decoration: BoxDecoration(
    border: Border.all(
      color: Colors.red[500],
    ),
    borderRadius: BorderRadius.all(Radius.circular(20))
  ),
  child: ...
)

Example 2: circular container flutter

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}


class _MyAppState extends State {
  double padValue = 0;
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text("Container as a Circle"),
        ),

        body: Container(
          margin: EdgeInsets.all(100.0),
          decoration: BoxDecoration(
            color: Colors.orange,
            shape: BoxShape.circle
          ),
        )
      ),
    );
  }
}