Flutter 参数类型';列表<;字符串>';can';不能分配给参数类型';字符串';。dart上的dart(参数类型不可分配)
无法将“String”类型的值分配给“String”类型的变量。 尝试更改变量的类型,或将右侧类型强制转换为“字符串”。dart(无效的\u赋值)Flutter 参数类型';列表<;字符串>';can';不能分配给参数类型';字符串';。dart上的dart(参数类型不可分配),flutter,Flutter,无法将“String”类型的值分配给“String”类型的变量。 尝试更改变量的类型,或将右侧类型强制转换为“字符串”。dart(无效的\u赋值) 后期字符串制造商; 后期双燃料能力; 后期双燃料剩余; 字符串showInfo()=> “$manufacturer:$fuelCapacity剩余的$fuelCapacity(critical:$criticalFuelLevel)”; double get criticalFuelLevel=>fuelCapacity*0.1; 设置newfue
后期字符串制造商;
后期双燃料能力;
后期双燃料剩余;
字符串showInfo()=>
“$manufacturer:$fuelCapacity剩余的$fuelCapacity(critical:$criticalFuelLevel)”;
double get criticalFuelLevel=>fuelCapacity*0.1;
设置newfuelreserving(双val)=>fuelreserving=val;
//默认构造函数
车辆(
{这是必需的。制造商,
所需的燃料容量,
需要此参数(0});
//命名构造函数
车辆。从地图(地图地图){
this.manufacturer=map[“manufacturer”];
this.fuelCapacity=double.parse([“fuelCapacity”]);
this.fuelRemaining=double.parse(['fuelRemaining']);
}
}
void main(){
无功车辆=
车辆(制造商:“宝马”,燃料容量:55,剩余燃料:20);
vehicle.newfuelresisting=20;
var vehicle2=车辆.fromMap(
{“制造商”:“起亚”,“燃料容量”:“50”,“剩余燃料”:“20”);
打印(vehicle2.showInfo());
}```
其原因是映射[“制造商”]代码>无法确定制造商是否在地图中。如果它确实存在,您可以告诉Dart它不能像那样为空(最后为a):
如果您还需要什么,或者问题不存在,请告诉我:)
late String manufacturer;
late double fuelCapacity;
late double fuelRemaining;
String showInfo() =>
'$manufacturer: $fuelRemaining of $fuelCapacity (critical: $criticalFuelLevel)';
double get criticalFuelLevel => fuelCapacity * 0.1;
set newFuelRemaining(double val) => fuelRemaining = val;
// default constructor
Vehicle(
{required this.manufacturer,
required this.fuelCapacity,
required this.fuelRemaining});
// named constructor
Vehicle.fromMap(Map<String,String> map) {
this.manufacturer = map["manufacturer"];
this.fuelCapacity = double.parse(["fuelCapacity"]);
this.fuelRemaining = double.parse(['fuelRemaining']);
}
}
void main() {
var vehicle =
Vehicle(manufacturer: 'BMW', fuelCapacity: 55, fuelRemaining: 20);
vehicle.newFuelRemaining = 20;
var vehicle2 = Vehicle.fromMap(
{'manufacturer': 'KIA', 'fuelCapacity': '50', 'fuelRemaining': '20'});
print(vehicle2.showInfo());
}```
this.manufacturer = map["manufacturer"]!;