如何在项目DropdownButton中添加下划线

Question

我如何为DropdownButton项目添加下划线，我已经尝试过如下所示的下划线，但是没有用

DropdownButton<String>(
                isExpanded: true,
                hint: Text("Status"),
                value: value.selected,
                underline: Container(
                    height: 2,
                    color: Colors.deepPurpleAccent,
                ),
                items: items
                    .map((key, value) {
                      return MapEntry(
                          key,
                          DropdownMenuItem<String>(
                            value: key,
                            child: Text(value),
                          ));
                    })
                    .values
                    .toList(),
                onChanged: (String val) {
                  value.selected = val;
                },
              )

Answer 1

SizedBox(
  width: 100.0,
  child: DropdownButtonFormField<int>(
    decoration: InputDecoration(
        border: UnderlineInputBorder(
            borderSide:
                BorderSide(color: Colors.white))),
    value: 2,
    items: <DropdownMenuItem<int>>[
      DropdownMenuItem<int>(
        value: 1,
        child: Text("Owner"),
      ),
      DropdownMenuItem<int>(
        value: 2,
        child: Text("Member"),
      ),
    ],
  ),