dart语言:Map <Object,String>如何添加新对？

Question

鉴于:

Map<WebSocket,String> mListUser;
mListUser= new  Map<WebSocket,String>();

从我现在理解的添加新元素我应该做:

mListUser[socket]="string";

而是我得到:

type 'String' is not a subtype of type 'int' of 'index'.

我究竟做错了什么？

Answer 1

也许有帮助

final test = Map<String, int>();
test.putIfAbsent('58', () => 56);

如果键不存在，它将被放入地图中。

Answer 2

也许有帮助。

Map<Object,String> map1= new Map<Object,String>();
Collections c = new Collections(); //some random class

map1[new Collections()]="arg1";
map1[c]="arg2";

map1.forEach((k,v)=>print("out: $k $v"));
print(map1[c]);

得到这个输出：

out: Instance of 'Collections' arg2
out: Instance of 'Collections' arg1
arg2