飛鏢。子類和構造函數初始值設定項列表

Question

我玩Dart（通過Dart語言遊覽），我發現我不能在子類上使用初始化列表。爲什麼？

main() { 
    var rbt = new Robot.fromJson({'x':21, 'y':21}); 
} 

class Human { 

} 

class Robot extends Human { 
    int x; 
    int y; 
    Robot.fromJSON(Map map) : x = map['x'], y = map['y'] { 
    print('Robot location is $x, $y'); 
    } 
} 

導致錯誤：

Exception: No constructor 'Robot.fromJson' declared in class 'Robot'. 

NoSuchMethodError: method not found: 'Robot.fromJson' 
Receiver: Type: class 'Robot' 
Arguments: [Instance of '_LinkedHashMap'] 

Answer 1

達特是區分大小寫的

fromJSON VS fromJson