异常类型 Future(void) in not subtype of Future<AnimationController>
Exception type Future(void) in not subtype of Future<AnimationController>
下面的代码在 flutter 中执行布局的创建，要创建布局，我必须首先确保执行 set 函数以使其使用 future builder 但是当我 运行 我的代码以下错误。
它告诉我存在以下错误， future 不是 future 的子类型，
理论上都是从对象派生的，所以 dart 上不应该有继承问题，这是因为什么？
错误：
type Future(void) in not subtype of Future
颤动代码：
import ...
double latitudine=0;
Future<void> setValori() async {
latitudine=await Gps.getLatitudine();
print("Latitudine: "+latitudine.toString());
print("\n \n Sono dentro set valori \n \n");
}
class MediterranesnDietView extends StatelessWidget {
final AnimationController animationController;
final Animation animation;
const MediterranesnDietView(
{Key key, this.animationController, this.animation})
: super(key: key);
@override
Widget build(BuildContext context) {
return FutureBuilder<AnimatedBuilder>(
future: setValori(),
builder: (BuildContext context, AsyncSnapshot<AnimatedBuilder> snapshot) {
return AnimatedBuilder(
animation: animationController,
builder: (BuildContext context, Widget child) {
return FadeTransition(
opacity: animation,
child: new Transform(
transform: new Matrix4.translationValues(
0.0, 30 * (1.0 - animation.value), 0.0),
child: Padding(
padding: const EdgeInsets.only(
left: 24, right: 24, top: 16, bottom: 18),
child: Container(
decoration: BoxDecoration(
color: FintnessAppTheme.white,
borderRadius: BorderRadius.only(
topLeft: Radius.circular(8.0),
bottomLeft: Radius.circular(8.0),
bottomRight: Radius.circular(8.0),
topRight: Radius.circular(68.0)),
boxShadow: <BoxShadow>[
BoxShadow(
color: FintnessAppTheme.grey.withOpacity(0.2),
offset: Offset(1.1, 1.1),
blurRadius: 10.0),
],
),
child: Column(
children: <Widget>[
Padding(
padding:
const EdgeInsets.only(top: 16, left: 16, right: 16),
child: Row(
children: <Widget>[
Expanded(
child: Padding(
padding: const EdgeInsets.only(
left: 8, right: 8, top: 4),
child: Column(
children: <Widget>[
Row(
children: <Widget>[
Container(
height: 48,
width: 2,
decoration: BoxDecoration(
color: HexColor('#87A0E5')
.withOpacity(0.5),
borderRadius: BorderRadius.all(
Radius.circular(4.0)),
),
),
Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
mainAxisAlignment:
MainAxisAlignment.center,
crossAxisAlignment:
CrossAxisAlignment.start,
children: <Widget>[
Padding(
padding: const EdgeInsets.only(
left: 4, bottom: 2),
child: Text(
'Latitudine',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily:
FintnessAppTheme.fontName,
fontWeight: FontWeight.w500,
fontSize: 16,
letterSpacing: -0.1,
color: FintnessAppTheme.grey
.withOpacity(0.5),
),
),
),
Row(
mainAxisAlignment:
MainAxisAlignment.center,
crossAxisAlignment:
CrossAxisAlignment.end,
children: <Widget>[
SizedBox(
width: 28,
height: 28,
child: Image.asset(
"assets/Home/eaten.png"),
),
Padding(
padding:
const EdgeInsets.only(
left: 4, bottom: 3),
child: Text(
'${(latitudine * animation.value).toInt()}',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily:
FintnessAppTheme
.fontName,
fontWeight:
FontWeight.w600,
fontSize: 16,
color: FintnessAppTheme
.darkerText,
),
),
),
Padding(
padding:
const EdgeInsets.only(
left: 4, bottom: 3),
child: Text(
'',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily:
FintnessAppTheme
.fontName,
fontWeight:
FontWeight.w600,
fontSize: 12,
letterSpacing: -0.2,
color: FintnessAppTheme
.grey
.withOpacity(0.5),
),
),
),
],
)
],
),
)
],
),
SizedBox(
height: 8,
),
Row(
children: <Widget>[
Container(
height: 48,
width: 2,
decoration: BoxDecoration(
color: HexColor('#F56E98')
.withOpacity(0.5),
borderRadius: BorderRadius.all(
Radius.circular(4.0)),
),
),
Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
mainAxisAlignment:
MainAxisAlignment.center,
crossAxisAlignment:
CrossAxisAlignment.start,
children: <Widget>[
Padding(
padding: const EdgeInsets.only(
left: 4, bottom: 2),
child: Text(
'Longitudine',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily:
FintnessAppTheme.fontName,
fontWeight: FontWeight.w500,
fontSize: 16,
letterSpacing: -0.1,
color: FintnessAppTheme.grey
.withOpacity(0.5),
),
),
),
Row(
mainAxisAlignment:
MainAxisAlignment.center,
crossAxisAlignment:
CrossAxisAlignment.end,
children: <Widget>[
SizedBox(
width: 28,
height: 28,
child: Image.asset(
"assets/Home/burned.png"),
),
Padding(
padding:
const EdgeInsets.only(
left: 4, bottom: 3),
child: Text(
'${(102 * animation.value).toInt()}',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily:
FintnessAppTheme
.fontName,
fontWeight:
FontWeight.w600,
fontSize: 16,
color: FintnessAppTheme
.darkerText,
),
),
),
Padding(
padding:
const EdgeInsets.only(
left: 8, bottom: 3),
child: Text(
'Kcal',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily:
FintnessAppTheme
.fontName,
fontWeight:
FontWeight.w600,
fontSize: 12,
letterSpacing: -0.2,
color: FintnessAppTheme
.grey
.withOpacity(0.5),
),
),
),
],
)
],
),
)
],
)
],
),
),
),
Padding(
padding: const EdgeInsets.only(right: 16),
child: Center(
child: Stack(
overflow: Overflow.visible,
children: <Widget>[
Padding(
padding: const EdgeInsets.all(8.0),
child: Container(
width: 100,
height: 100,
decoration: BoxDecoration(
color: FintnessAppTheme.white,
borderRadius: BorderRadius.all(
Radius.circular(100.0),
),
border: new Border.all(
width: 4,
color: FintnessAppTheme
.nearlyDarkBlue
.withOpacity(0.2)),
),
child: Column(
mainAxisAlignment:
MainAxisAlignment.center,
crossAxisAlignment:
CrossAxisAlignment.center,
children: <Widget>[
Text(
'${(1503 * animation.value).toInt()}',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily:
FintnessAppTheme.fontName,
fontWeight: FontWeight.normal,
fontSize: 24,
letterSpacing: 0.0,
color: FintnessAppTheme
.nearlyDarkBlue,
),
),
Text(
'Kcal left',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily:
FintnessAppTheme.fontName,
fontWeight: FontWeight.bold,
fontSize: 12,
letterSpacing: 0.0,
color: FintnessAppTheme.grey
.withOpacity(0.5),
),
),
],
),
),
),
Padding(
padding: const EdgeInsets.all(4.0),
child: CustomPaint(
painter: CurvePainter(
colors: [
FintnessAppTheme.nearlyDarkBlue,
HexColor("#8A98E8"),
HexColor("#8A98E8")
],
angle: 140 +
(360 - 140) *
(1.0 - animation.value)),
child: SizedBox(
width: 108,
height: 108,
),
),
)
],
),
),
)
],
),
),
Padding(
padding: const EdgeInsets.only(
left: 24, right: 24, top: 8, bottom: 8),
child: Container(
height: 2,
decoration: BoxDecoration(
color: FintnessAppTheme.background,
borderRadius: BorderRadius.all(Radius.circular(4.0)),
),
),
),
Padding(
padding: const EdgeInsets.only(
left: 24, right: 24, top: 8, bottom: 16),
child: Row(
children: <Widget>[
Expanded(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Text(
'Carbs',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily: FintnessAppTheme.fontName,
fontWeight: FontWeight.w500,
fontSize: 16,
letterSpacing: -0.2,
color: FintnessAppTheme.darkText,
),
),
Padding(
padding: const EdgeInsets.only(top: 4),
child: Container(
height: 4,
width: 70,
decoration: BoxDecoration(
color:
HexColor('#87A0E5').withOpacity(0.2),
borderRadius: BorderRadius.all(
Radius.circular(4.0)),
),
child: Row(
children: <Widget>[
Container(
width: ((70 / 1.2) * animation.value),
height: 4,
decoration: BoxDecoration(
gradient: LinearGradient(colors: [
HexColor('#87A0E5'),
HexColor('#87A0E5')
.withOpacity(0.5),
]),
borderRadius: BorderRadius.all(
Radius.circular(4.0)),
),
)
],
),
),
),
Padding(
padding: const EdgeInsets.only(top: 6),
child: Text(
'12g left',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily: FintnessAppTheme.fontName,
fontWeight: FontWeight.w600,
fontSize: 12,
color: FintnessAppTheme.grey
.withOpacity(0.5),
),
),
),
],
),
),
...
),
),
),
);
},
);
});
}
}
作为您的方法 setValori() returns 类型为 void 的 Future 您需要更改以下行：
return FutureBuilder<AnimatedBuilder>
这应该是
return FutureBuilder<void>
错误表明，您给 FutureBuilder 的 Future 与 Builders 通用类型不匹配。
您使用通用参数 AnimatedBuilder 定义了 FutureBuilder<AnimatedBuilder>，它需要一个 Future<AnimatedBuilder>。函数 setValori() 返回 Future<void>.
如果您将 FutureBuilder<AnimatedBuilder> 更改为 FutureBuilder<void> 并将 AsyncSnapshot<AnimatedBuilder> 更改为 AsyncSnapshot<void>，您就解决了问题。
下面的代码在 flutter 中执行布局的创建，要创建布局，我必须首先确保执行 set 函数以使其使用 future builder 但是当我 运行 我的代码以下错误。 它告诉我存在以下错误， future 不是 future 的子类型， 理论上都是从对象派生的，所以 dart 上不应该有继承问题，这是因为什么？
错误：
type Future(void) in not subtype of Future
颤动代码：
import ...
double latitudine=0;
Future<void> setValori() async {
latitudine=await Gps.getLatitudine();
print("Latitudine: "+latitudine.toString());
print("\n \n Sono dentro set valori \n \n");
}
class MediterranesnDietView extends StatelessWidget {
final AnimationController animationController;
final Animation animation;
const MediterranesnDietView(
{Key key, this.animationController, this.animation})
: super(key: key);
@override
Widget build(BuildContext context) {
return FutureBuilder<AnimatedBuilder>(
future: setValori(),
builder: (BuildContext context, AsyncSnapshot<AnimatedBuilder> snapshot) {
return AnimatedBuilder(
animation: animationController,
builder: (BuildContext context, Widget child) {
return FadeTransition(
opacity: animation,
child: new Transform(
transform: new Matrix4.translationValues(
0.0, 30 * (1.0 - animation.value), 0.0),
child: Padding(
padding: const EdgeInsets.only(
left: 24, right: 24, top: 16, bottom: 18),
child: Container(
decoration: BoxDecoration(
color: FintnessAppTheme.white,
borderRadius: BorderRadius.only(
topLeft: Radius.circular(8.0),
bottomLeft: Radius.circular(8.0),
bottomRight: Radius.circular(8.0),
topRight: Radius.circular(68.0)),
boxShadow: <BoxShadow>[
BoxShadow(
color: FintnessAppTheme.grey.withOpacity(0.2),
offset: Offset(1.1, 1.1),
blurRadius: 10.0),
],
),
child: Column(
children: <Widget>[
Padding(
padding:
const EdgeInsets.only(top: 16, left: 16, right: 16),
child: Row(
children: <Widget>[
Expanded(
child: Padding(
padding: const EdgeInsets.only(
left: 8, right: 8, top: 4),
child: Column(
children: <Widget>[
Row(
children: <Widget>[
Container(
height: 48,
width: 2,
decoration: BoxDecoration(
color: HexColor('#87A0E5')
.withOpacity(0.5),
borderRadius: BorderRadius.all(
Radius.circular(4.0)),
),
),
Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
mainAxisAlignment:
MainAxisAlignment.center,
crossAxisAlignment:
CrossAxisAlignment.start,
children: <Widget>[
Padding(
padding: const EdgeInsets.only(
left: 4, bottom: 2),
child: Text(
'Latitudine',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily:
FintnessAppTheme.fontName,
fontWeight: FontWeight.w500,
fontSize: 16,
letterSpacing: -0.1,
color: FintnessAppTheme.grey
.withOpacity(0.5),
),
),
),
Row(
mainAxisAlignment:
MainAxisAlignment.center,
crossAxisAlignment:
CrossAxisAlignment.end,
children: <Widget>[
SizedBox(
width: 28,
height: 28,
child: Image.asset(
"assets/Home/eaten.png"),
),
Padding(
padding:
const EdgeInsets.only(
left: 4, bottom: 3),
child: Text(
'${(latitudine * animation.value).toInt()}',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily:
FintnessAppTheme
.fontName,
fontWeight:
FontWeight.w600,
fontSize: 16,
color: FintnessAppTheme
.darkerText,
),
),
),
Padding(
padding:
const EdgeInsets.only(
left: 4, bottom: 3),
child: Text(
'',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily:
FintnessAppTheme
.fontName,
fontWeight:
FontWeight.w600,
fontSize: 12,
letterSpacing: -0.2,
color: FintnessAppTheme
.grey
.withOpacity(0.5),
),
),
),
],
)
],
),
)
],
),
SizedBox(
height: 8,
),
Row(
children: <Widget>[
Container(
height: 48,
width: 2,
decoration: BoxDecoration(
color: HexColor('#F56E98')
.withOpacity(0.5),
borderRadius: BorderRadius.all(
Radius.circular(4.0)),
),
),
Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
mainAxisAlignment:
MainAxisAlignment.center,
crossAxisAlignment:
CrossAxisAlignment.start,
children: <Widget>[
Padding(
padding: const EdgeInsets.only(
left: 4, bottom: 2),
child: Text(
'Longitudine',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily:
FintnessAppTheme.fontName,
fontWeight: FontWeight.w500,
fontSize: 16,
letterSpacing: -0.1,
color: FintnessAppTheme.grey
.withOpacity(0.5),
),
),
),
Row(
mainAxisAlignment:
MainAxisAlignment.center,
crossAxisAlignment:
CrossAxisAlignment.end,
children: <Widget>[
SizedBox(
width: 28,
height: 28,
child: Image.asset(
"assets/Home/burned.png"),
),
Padding(
padding:
const EdgeInsets.only(
left: 4, bottom: 3),
child: Text(
'${(102 * animation.value).toInt()}',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily:
FintnessAppTheme
.fontName,
fontWeight:
FontWeight.w600,
fontSize: 16,
color: FintnessAppTheme
.darkerText,
),
),
),
Padding(
padding:
const EdgeInsets.only(
left: 8, bottom: 3),
child: Text(
'Kcal',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily:
FintnessAppTheme
.fontName,
fontWeight:
FontWeight.w600,
fontSize: 12,
letterSpacing: -0.2,
color: FintnessAppTheme
.grey
.withOpacity(0.5),
),
),
),
],
)
],
),
)
],
)
],
),
),
),
Padding(
padding: const EdgeInsets.only(right: 16),
child: Center(
child: Stack(
overflow: Overflow.visible,
children: <Widget>[
Padding(
padding: const EdgeInsets.all(8.0),
child: Container(
width: 100,
height: 100,
decoration: BoxDecoration(
color: FintnessAppTheme.white,
borderRadius: BorderRadius.all(
Radius.circular(100.0),
),
border: new Border.all(
width: 4,
color: FintnessAppTheme
.nearlyDarkBlue
.withOpacity(0.2)),
),
child: Column(
mainAxisAlignment:
MainAxisAlignment.center,
crossAxisAlignment:
CrossAxisAlignment.center,
children: <Widget>[
Text(
'${(1503 * animation.value).toInt()}',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily:
FintnessAppTheme.fontName,
fontWeight: FontWeight.normal,
fontSize: 24,
letterSpacing: 0.0,
color: FintnessAppTheme
.nearlyDarkBlue,
),
),
Text(
'Kcal left',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily:
FintnessAppTheme.fontName,
fontWeight: FontWeight.bold,
fontSize: 12,
letterSpacing: 0.0,
color: FintnessAppTheme.grey
.withOpacity(0.5),
),
),
],
),
),
),
Padding(
padding: const EdgeInsets.all(4.0),
child: CustomPaint(
painter: CurvePainter(
colors: [
FintnessAppTheme.nearlyDarkBlue,
HexColor("#8A98E8"),
HexColor("#8A98E8")
],
angle: 140 +
(360 - 140) *
(1.0 - animation.value)),
child: SizedBox(
width: 108,
height: 108,
),
),
)
],
),
),
)
],
),
),
Padding(
padding: const EdgeInsets.only(
left: 24, right: 24, top: 8, bottom: 8),
child: Container(
height: 2,
decoration: BoxDecoration(
color: FintnessAppTheme.background,
borderRadius: BorderRadius.all(Radius.circular(4.0)),
),
),
),
Padding(
padding: const EdgeInsets.only(
left: 24, right: 24, top: 8, bottom: 16),
child: Row(
children: <Widget>[
Expanded(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Text(
'Carbs',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily: FintnessAppTheme.fontName,
fontWeight: FontWeight.w500,
fontSize: 16,
letterSpacing: -0.2,
color: FintnessAppTheme.darkText,
),
),
Padding(
padding: const EdgeInsets.only(top: 4),
child: Container(
height: 4,
width: 70,
decoration: BoxDecoration(
color:
HexColor('#87A0E5').withOpacity(0.2),
borderRadius: BorderRadius.all(
Radius.circular(4.0)),
),
child: Row(
children: <Widget>[
Container(
width: ((70 / 1.2) * animation.value),
height: 4,
decoration: BoxDecoration(
gradient: LinearGradient(colors: [
HexColor('#87A0E5'),
HexColor('#87A0E5')
.withOpacity(0.5),
]),
borderRadius: BorderRadius.all(
Radius.circular(4.0)),
),
)
],
),
),
),
Padding(
padding: const EdgeInsets.only(top: 6),
child: Text(
'12g left',
textAlign: TextAlign.center,
style: TextStyle(
fontFamily: FintnessAppTheme.fontName,
fontWeight: FontWeight.w600,
fontSize: 12,
color: FintnessAppTheme.grey
.withOpacity(0.5),
),
),
),
],
),
),
...
),
),
),
);
},
);
});
}
}
作为您的方法 setValori() returns 类型为 void 的 Future 您需要更改以下行：
return FutureBuilder<AnimatedBuilder>
这应该是
return FutureBuilder<void>
错误表明，您给 FutureBuilder 的 Future 与 Builders 通用类型不匹配。
您使用通用参数 AnimatedBuilder 定义了 FutureBuilder<AnimatedBuilder>，它需要一个 Future<AnimatedBuilder>。函数 setValori() 返回 Future<void>.
如果您将 FutureBuilder<AnimatedBuilder> 更改为 FutureBuilder<void> 并将 AsyncSnapshot<AnimatedBuilder> 更改为 AsyncSnapshot<void>，您就解决了问题。