Flutter Dropdownbutton selected value is not changing

Question

Flutter Dropdownbutton selected value is not changing I am using dropdownbutton and mapping data using Product model but onchange my value is not changing

DropdownButtonHideUnderline(
                        child: DropdownButton<Product>(
                          hint: Text("Select Product"),
                          dropdownColor: Colors.white,
                          isExpanded: true,
                          items: _productController.products
                              .map((Product value) {
                            return new DropdownMenuItem<Product>(
                              value: value,
                              child: new Text(value.productName),
                            );
                          }).toList(),
                          onChanged: (Product val) {
                            _stockController.price.text = val.price;
                            _stockController.productName.text = val.productName;
                            selectedProduct = val.productName;
                            TextStyle(color: Colors.black);
                            setState(() {});
                          },
                        ),
                      ),

Answer 1

You didn't specify the value property of this widget. I think it should be set to value of selectedProduct . And what the separate TextStyle ? It is used as value for style property of widgets and cannot be used as standalone.