flutter container

Container(
            alignment: Alignment.center,
            child: Text('Container'),
            width: 200.0,
            height: 200.0,
            decoration: BoxDecoration(
              color: Colors.purple[200],
              borderRadius: BorderRadius.circular(60.0)              
            )
          ),

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"),
)

// If you want the whole table to be Centered, use the mainAxisAlignment property of Column.
///Column
mainAxisAlignment: MainAxisAlignment.center //Center Column contents vertically,
crossAxisAlignment: CrossAxisAlignment.center //Center Column contents horizontally,

///Row
mainAxisAlignment: MainAxisAlignment.center //Center Row contents horizontally,
crossAxisAlignment: CrossAxisAlignment.center //Center Row contents vertically,