method elementAt() with index without listview.builder?-CodePudding

How can I get all elements from the map, if I need to use index without listView.builder?

I created the dropdown menu, and as I inderstood it creates the list with map() method for DropDownItem() widget. I am trying to use it, but get raw string data and it shouldn't be so. Also API is working on websockets and it returns Map like this {2: GMT 02:00, 3: GMT 03:00}, (it returns Object but I need to use as String)

So when I trying to put it in the UI without raw strings from API, I do it like this:

 items: snapshot.data?.values
                  .map((e) => DropdownMenuItem<String>(
                      value: e,
                      child:
                          Text(snapshot.data?.values.elementAt(index) ?? '')))
                  .toList(),

So the question is, how can I use elementAt() method and put in it index without creating listview.builder to get the index of element? May be should I manipulate with entries? I was trying to create int? index , but it doesen't work.

If it is important, the length of elements is 11.

CodePudding user response：

items: snapshot.data?.values
                  .map((e) => DropdownMenuItem<String>(
                      value: e,
                      child:
                          Text(snapshot.data?.values.elementAt(index) ?? '')))
                  .toList(),

Here e by itself is a single entry from the value. so you can use the same value here in child too like unless you wish to access index of some other element.

items: snapshot.data?.values
                  .map((e) => DropdownMenuItem<String>(
                      value: e,
                      child:
                          Text(e.toString()??"")))
                  .toList(),

CodePudding user response：

You can use List.generate

DropdownButton(
    items: List.generate(values.length, (index) => ..),

Or for loop

DropdownButton(
  items: [
    for (int i = 0; i < values.length; i  )
      DropdownMenuItem(child: child)
  ],