[button] How do I disable a Button in Flutter?

For disabling any Button in flutter such as FlatButton, RaisedButton, MaterialButton, IconButton etc all you need to do is to set the onPressed and onLongPress properties to null. Below is some simple examples for some of the buttons:

FlatButton (Enabled)

FlatButton(
  onPressed: (){}, 
  onLongPress: null, // Set one as NOT null is enough to enable the button
  textColor: Colors.black,
  disabledColor: Colors.orange,
  disabledTextColor: Colors.white,
  child: Text('Flat Button'),
),

enter image description here enter image description here

FlatButton (Disabled)

FlatButton(
  onPressed: null,
  onLongPress: null,
  textColor: Colors.black,
  disabledColor: Colors.orange,
  disabledTextColor: Colors.white,
  child: Text('Flat Button'),
),

enter image description here

RaisedButton (Enabled)

RaisedButton(
  onPressed: (){},
  onLongPress: null, // Set one as NOT null is enough to enable the button
  // For when the button is enabled
  color: Colors.lightBlueAccent,
  textColor: Colors.black,
  splashColor: Colors.blue,
  elevation: 8.0,

  // For when the button is disabled
  disabledTextColor: Colors.white,
  disabledColor: Colors.orange,
  disabledElevation: 0.0,

  child: Text('Raised Button'),
),

enter image description here

RaisedButton (Disabled)

RaisedButton(
  onPressed: null,
  onLongPress: null,
  // For when the button is enabled
  color: Colors.lightBlueAccent,
  textColor: Colors.black,
  splashColor: Colors.blue,
  elevation: 8.0,

  // For when the button is disabled
  disabledTextColor: Colors.white,
  disabledColor: Colors.orange,
  disabledElevation: 0.0,

  child: Text('Raised Button'),
),

enter image description here

IconButton (Enabled)

IconButton(
  onPressed: () {},
  icon: Icon(Icons.card_giftcard_rounded),
  color: Colors.lightBlueAccent,
            
  disabledColor: Colors.orange,
),

enter image description here enter image description here

IconButton (Disabled)

IconButton(
  onPressed: null,
  icon: Icon(Icons.card_giftcard_rounded),
  color: Colors.lightBlueAccent,
            
  disabledColor: Colors.orange,
),

enter image description here

Note: Some of buttons such as IconButton have only the onPressed property.