Error: Either zero or 2 or more [DropdownMenuItem]s were detected with the same value I/flutter (18363): 'package:flutter/src/material/dropdown.dart':

Question

Error code Hi I\'m new to flutter and have a question about dropdownbutton regarding using the same values for multiple dropdownbutton.

From my understanding from th

Answer 1

This exception you have because of mistakes:

1. No _value1 and _value2 initialization.
2. When you initialize them make sure that _value1 and _value2 right from nameList e.g.

_value1 = nameList[0];
_value2 = nameList[3];

this is important step with complex data type, but in your case

_value1 = "Name1";
_value2 = "Name4";

will be sufficient.

Full example:

  String _value1;
  String _value2;

  final List nameList = [
    "Name1",
    "Name2",
    "Name3",
    "Name4",
    "Name5",
    "Name6",
    "Name7",
    "Name8"
  ];

  /// initialization is here:
  @override
 void initState() {
    super.initState();
    _value1 = nameList[0];
    _value2 = nameList[3];
  }

  @override
  Widget build(BuildContext context) {
    return ListView(
      children: [
        Row(
          children: [
            Text('Name: '),
            Center(
              child: DropdownButton(
                value: _value1,
                onChanged: (value) {
                  setState(() {
                    _value1 = value;
                  });
                },
                items: nameList.map(
                  (item) {
                    return DropdownMenuItem(
                      value: item,
                      child: new Text(item),
                    );
                  },
                ).toList(),
              ),
            ),
          ],
        ),
        Row(
          children: [
            Text('Name: '),
            Center(
              child: DropdownButton(
                value: _value2,
                onChanged: (value) {
                  setState(() {
                    _value2 = value;
                  });
                },
                items: nameList.map(
                  (item) {
                    return DropdownMenuItem(
                      value: item,
                      child: new Text(item),
                    );
                  },
                ).toList(),
              ),
            ),
          ],
        ),
      ],
    );
  }
}