dart - 将多张 map 组合/合并为一张 map

Question

如何将 dart 中的 2 个或更多 map 组合/合并为 1 个 map ？ 例如我有类似的东西:

 var firstMap = {"1":"2"};
 var secondMap = {"1":"2"};
 var thirdMap = {"1":"2"};

我想要:

 var finalMap = {"1":"2", "1":"2", "1":"2"};

Answer 1

您可以使用Map对象的addAll方法

var firstMap = {"1":"2"};
var secondMap = {"2":"3"};

var thirdMap = {};

thirdMap.addAll(firstMap);
thirdMap.addAll(secondMap);

print(thirdMap);

或者

var thirdMap = {}..addAll(firstMap)..addAll(secondMap);

更新

自 dart sdk 2.3 起 您可以使用扩展运算符 ...

final firstMap = {"1":"2"};
final secondMap = {"2":"3"};

final thirdMap = {
   ...firstMap,
   ...secondMap,
};