Round container with border in flutter code example

Example 1: flutter container rounded corners

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

Example 2: flutter round container

QUESTION: Flutter give container rounded border

ANSWER1: 

Container(
    decoration: BoxDecoration(
    shape: BoxShape.circle,
    ),
    child:   ...
    ),

ANSWER 2:
Container(
  decoration: BoxDecoration(
    border: Border.all(
      color: Colors.red[500],
    ),
    borderRadius: BorderRadius.all(Radius.circular(20))
  ),
  child: ...
)

Example 3: flutter border radius container

Container(
   decoration: BoxDecoration(
   borderRadius: BorderRadius.circular(20.0),
   color: Colors.red,
   ),
   child: 
),