代码将解释一切:
//modal for list
class MyModal
{
int myField1;
List<MyModal> adjacentNodes;
MyModal(this.myField1)
{
adjacentNodes= new List<MyModal>();
}
}
//pre code
List<MyModal> originalList = new List<MyModal>();
originalList.add(new MyModal(1,"firstBuddy"));
//copying list
List<MyModal> secondList = new List<MyModal>();
secondList.addAll(originalList);
//Modifing copy list
secondList.adjacentNodes.add(new MyModal(2,"anotherBuddy"));
//Also modifies original list
print(originalList[0].childs.length); //prints 1, it should prints 0
如何在不影响原始列表的情况下对第二个列表进行更改?
class MyModal {
int myField1;
String myField2;
List<MyModal> adjacentNodes;
MyModal(this.myField1,this.myField2);
MyModal.clone(MyModal source) :
this.myField1 = source.myField1,
this.myField2 = source.myField2,
this.adjacentNodes = source.adjacentNodes.map((item) => new MyModal.clone(item)).toList();
}
var secondList = originalList.map((item) => new MyModal.clone(item)).toList();
如果是以下成员MyModal
是非原始类型,例如String
, int
, double
, num
, bool
,那么clone()
方法还需要克隆引用指向的实例。
我认为对于您的用例,使用不可变值是更好的方法,例如https://pub.dartlang.org/packages/built_value https://pub.dartlang.org/packages/built_value
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