Dropdown selection not displaying with Flutter

Question

I' m gettings items from JSON and displaying them in a dropdown. When the person select an item from the dropdown list, I get the selection but the selected item doesn't change.

For example we have (tokyo, paris, new york) in the list. By default selection is tokyo. When the person select paris, I get it but the selection doesn't change in the dropdown.

Here is my code:

new DropdownButton(
  value: cities.elementAt(0),
  hint: new Text("Ville"),
  items: cities.map((String value) {
    return new DropdownMenuItem(
      value: value,
      child: new Row(
        children: <Widget>[
          new Icon(
            Icons.location_city,
            color: Colors.deepOrange,
          ),
          new Text(value)
        ],
      ),
    );
  }).toList(),
  onChanged: (String value) {
    getTravelCity(value);
  },
),

When the person select an item, it still showing the default value.

Answer 1

make sure you are not declaring the selectedValue inside the Widget the below example works for me perfectly.

here is the working code on dartpad to test it out

var currentSelectedValue;
const deviceTypes = ["Mac", "Windows", "Mobile"];

 Widget typeFieldWidget() {
return Container(
  padding: EdgeInsets.symmetric(horizontal: 20),
  child: FormField<String>(
    builder: (FormFieldState<String> state) {
      return InputDecorator(
        decoration: InputDecoration(
            border: OutlineInputBorder(
                borderRadius: BorderRadius.circular(5.0))),
        child: DropdownButtonHideUnderline(
          child: DropdownButton<String>(
            hint: Text("Select Device"),
            value: currentSelectedValue,
            isDense: true,
            onChanged: (newValue) {
              setState(() {
                currentSelectedValue = newValue;
              });
              print(currentSelectedValue);
            },
            items: deviceTypes.map((String value) {
              return DropdownMenuItem<String>(
                value: value,
                child: Text(value),
              );
            }).toList(),
          ),
        ),
      );
    },
  ),
);
}