use border box flutter code example
Example 1: flutter container border
Container(
decoration: BoxDecoration(
border: Border.all(
color: Colors.red, // red as border color
),
),
child: Text("Your text...")
)
Example 2: border for container in flutter
new Container(
margin: const EdgeInsets.all(15.0),
padding: const EdgeInsets.all(3.0),
decoration: BoxDecoration(
border: Border.all(color: Colors.blueAccent)
),
child: Text("My Awesome Border"),
)