将下拉菜单项中的子项从text替换为ListTile，如果你需要每个项都有默认图标，你必须将String列表更改为List<Map<String，dynamic>>，如下所示：

List<Map<String, dynamic>> listPilihanstatus = [
  {'name': 'Mitsubishi', 'icon': Icons.safety_check},
  {'name': 'Yamaha', 'icon': Icons.access_alarm_outlined},
  {'name': 'Honda', 'icon': Icons.account_balance_sharp},
  {'name': 'Nissan', 'icon': Icons.sailing},
  {'name': 'Hyundai', 'icon': Icons.macro_off},
];

字符串
代码如下：

DropdownButtonFormField<String>(
                hint: const Text('Select your vehicle'),
                value: dropdownValue,
                decoration: const InputDecoration(
                  border: OutlineInputBorder(
                    borderRadius: BorderRadius.all(Radius.circular(10.0)),
                  ),
                ),
                onChanged: (String? newValue) {
                  setState(() {
                    dropdownValue = newValue!;
                  });
                },
                items: listPilihanstatus
                    .map<DropdownMenuItem<String>>((e) => DropdownMenuItem(
                          child:ListTile(
                            title: Text(e['name']),
                            trailing: Icon(e['icon']),
                          ),
                          value: e['name'],
                        ))
                    .toList()),

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