How to change background color of Elevated Button in Flutter from function?

I am new to Flutter, I started Flutter last week, And now I want to make a simple Xylophone app. I created the UI successfully and made a function playSound(int soundNumber) but when I call this function for playing sound, it gives me this error.

**The following _TypeError was thrown building Body(dirty, state: _BodyState#051c2):
type '_MaterialStatePropertyAll<dynamic>' is not a subtype of type 'MaterialStateProperty<Color?>?'**

Here's the code I wrote for playSound(int soundNumber) function.

void playSound(int soundNumber) {
final player = AudioCache();
player.play('note$soundNumber.wav');}

Expanded buildPlayButton({MaterialStateProperty color, int soundNumber}){
return Expanded(
  child: ElevatedButton(
    onPressed: () {
      playSound(soundNumber);
    },
    style: ButtonStyle(
      backgroundColor: color,
    ),
  ),
);}

Here is the point where I am calling this function.

Widget build(BuildContext context) {
return Column(
  crossAxisAlignment: CrossAxisAlignment.stretch,
  children: <Widget>[
    buildPlayButton(color: MaterialStateProperty.all(Colors.red), soundNumber: 1),
    buildPlayButton(color: MaterialStateProperty.all(Colors.orangeAccent), soundNumber: 2),
    buildPlayButton(color: MaterialStateProperty.all(Colors.yellow), soundNumber: 3),
    buildPlayButton(color: MaterialStateProperty.all(Colors.indigo), soundNumber: 4),
    buildPlayButton(color: MaterialStateProperty.all(Colors.blue), soundNumber: 5),
    buildPlayButton(color: MaterialStateProperty.all(Colors.lightGreenAccent), soundNumber: 6),
    buildPlayButton(color: MaterialStateProperty.all(Colors.green), soundNumber: 7),
  ],
);
}

How to call this function because it gives me the above-mentioned error?

You can style ElevatedButton by using the styleFrom static method or the ButtonStyle class. The first one is more convenience than the second one.

Using styleFrom to style an ElevatedButton:

ElevatedButton(
      child: Text('Button'),
      onPressed: () {},
      style: ElevatedButton.styleFrom({
           Color primary, // set the background color 
           Color onPrimary, 
           Color onSurface, 
           Color shadowColor, 
           double elevation, 
           TextStyle textStyle, 
           EdgeInsetsGeometry padding, 
           Size minimumSize, 
           BorderSide side, 
           OutlinedBorder shape, 
           MouseCursor enabledMouseCursor, 
           MouseCursor disabledMouseCursor, 
           VisualDensity visualDensity, 
           MaterialTapTargetSize tapTargetSize, 
           Duration animationDuration, 
           bool enableFeedback
     }),
),

Example:

ElevatedButton(
            child: Text('Button'),
            onPressed: () {},
            style: ElevatedButton.styleFrom(
                primary: Colors.purple,
                padding: EdgeInsets.symmetric(horizontal: 50, vertical: 20),
                textStyle: TextStyle(
                fontSize: 30,
                fontWeight: FontWeight.bold)),
),

Using ButtonStyle to style an ElevatedButton:

style: ButtonStyle({
  MaterialStateProperty<TextStyle> textStyle,    
  MaterialStateProperty<Color> backgroundColor,   
  MaterialStateProperty<Color> foregroundColor, 
  MaterialStateProperty<Color> overlayColor, 
  MaterialStateProperty<Color> shadowColor, 
  MaterialStateProperty<double> elevation, 
  MaterialStateProperty<EdgeInsetsGeometry> padding, 
  MaterialStateProperty<Size> minimumSize, 
  MaterialStateProperty<BorderSide> side, 
  MaterialStateProperty<OutlinedBorder> shape, 
  MaterialStateProperty<MouseCursor> mouseCursor,    
  VisualDensity visualDensity, 
  MaterialTapTargetSize tapTargetSize, 
  Duration animationDuration, 
  bool enableFeedback
})

Example

ElevatedButton(
            child: Text('Button'),
            onPressed: () {},
            style: ButtonStyle(
                backgroundColor: MaterialStateProperty.all(Colors.red),
                padding: MaterialStateProperty.all(EdgeInsets.all(50)),
                textStyle: MaterialStateProperty.all(TextStyle(fontSize: 30))),
),

Pass color as parameter and use MaterialStateProperty.all<Color>(color) to specify the color.

buildPlayButton(color: Colors.red, soundNumber: 1)

Expanded buildPlayButton({Color color, int soundNumber}){
return Expanded(
  child: ElevatedButton(
    onPressed: () {
      playSound(soundNumber);
    },
    style: ButtonStyle(
      backgroundColor: MaterialStateProperty.all<Color>(color),
    ),
  ),
);}

Sample button

In general

ElevatedButton(
  style: ElevatedButton.styleFrom(
	primary: Colors.red, // background
	onPrimary: Colors.yellow, // foreground
  ),
  onPressed: () {},
  child: Text('ElevatedButton with custom foreground/background'),
)

Sample button

Reference:

ElevatedButton class

ElevatedButton(onPressed: resetHandler,
               child: Text("button"),
               style: ElevatedButton.styleFrom(primary: Colors.amber),),

You have 3 Options to change the background color :

ElevatedButton.styleFrom : If you just want to change the background color and foreground color irrespective of the states then you can do as given below.

ElevatedButton(
  style: ElevatedButton.styleFrom(
    primary: Colors.red, // background
    onPrimary: Colors.white, // foreground
  ),
  onPressed: () { },
  child: Text('custom foreground/background'),
)

MaterialStateProperty.all : to override a ElevatedButtons default background(text/icon) color for all states.

 ElevatedButton(style:   
    ButtonStyle(
      backgroundColor: MaterialStateProperty.all(Colors.red),
    onPressed: () { },
    child: Text('custom foreground/background'),
    ));

MaterialStateProperty.resolveWith : By default, the elevated button inherits a blue color. We can tweak the default style using the style parameter and ButtonStyle class. Button has different states such as pressed, disabled, hovered etc. You can change the style for each state. In the below snippet, the default color of the button changes to green when it is pressed.

ElevatedButton(
  style: ButtonStyle(
    backgroundColor: MaterialStateProperty.resolveWith<Color>(
      (Set<MaterialState> states) {
        if (states.contains(MaterialState.pressed))
          return Colors.green;
        return null; // Use the component's default.
      },
    ),
  ),
)

Just use MaterialStateProperty.all(**YOUR COLOR**):

ElevatedButton(
            child: Text('Button'),
            onPressed: () {},
            style: ButtonStyle(
                backgroundColor: MaterialStateProperty.all(Colors.red),)
),

or like this: Just use ElevatedButton.styleFrom(primary: **YOUR COLOR**):

ElevatedButton(
            child: Text('Button'),
            onPressed: () {},
            style: ElevatedButton.styleFrom(primary: Colors.red),
)

Screenshot:

---

Code:

class _MyState extends State<MyPage> {
  bool _flag = true;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: ElevatedButton(
          onPressed: () => setState(() => _flag = !_flag),
          child: Text(_flag ? 'Red' : 'Green'),
          style: ElevatedButton.styleFrom(
            primary: _flag ? Colors.red : Colors.teal, // This is what you need!
          ),
        ),
      ),
    );
  }
}

style: ElevatedButton.styleFrom(primary : Colors.black),

ElevatedButton(
          onPressed: (){},
          child: Text('comprar'),
          style: ElevatedButton.styleFrom(
            primary: Theme.of(context).primaryColor
          )
        )

 style: ElevatedButton.styleFrom(
                        shape: RoundedRectangleBorder(
                          borderRadius: new BorderRadius.circular(30.0),
                        ),
                          primary: HexColor(HexColor.primarycolor),
                          textStyle: TextStyle(fontWeight: FontWeight.bold)),

style: ButtonStyle({  
  MaterialStateProperty.all(backgroundColor),   
),

Similarly, you can add MaterialStateProperty.all(<Value here>) to most properties of elevated button(elevation, padding, border etc).

Make sure to add onPressed: () {},

otherwise color will be gray