如何更改下拉菜单的文本颜色

Question

我正在尝试更改下拉菜单的文本颜色，但我失败了，这是我尝试过的

StreamBuilder(
                  stream: Firestore.instance.collection("country").snapshots(),
                  builder: (context, snapshot) {
                    if (!snapshot.hasData)
                      const Text("Loading.....");
                    else {
                      List<DropdownMenuItem> banks = [];
                      for (int i = 0; i < snapshot.data.documents.length; i++) {
                        DocumentSnapshot snap = snapshot.data.documents[i];
                        banks.add(
                          DropdownMenuItem(
                            child: Text(
                              snap.documentID,
                              style: TextStyle(color: Colors.blueAccent,fontSize: 20)
                            ),
                            value: "${snap.documentID}",
                          ),
                        );
                      }
                      return Row( 
                        mainAxisAlignment: MainAxisAlignment.center,
                        children: <Widget>[
                         
                          SizedBox(width:0), Container(
                            padding: EdgeInsets.all(16),
                            height: 60,
                            width: 360, 
                          
                         decoration: BoxDecoration(
                           
                           border: Border.all(width:2,color: wood_smoke), 
                           
          borderRadius: BorderRadius.circular(16),
          
          ),
  



                          child:
                          
                           DropdownButtonHideUnderline( 
                         child: DropdownButton( 
                           
                           style: TextStyle(  fontSize: 20, fontWeight: FontWeight.bold,
              color: wood_smoke, 
            ), 
                            items: banks,
                            onChanged: (newValue) {
                               
                               setState(() { 
                                 
                                 selectedBranch = newValue;


                               });

    

     





            },
                            value: selectedBranch,
                            isExpanded: false,
                            hint: new Text(
                              "Choose Bank and Branch",
                              style: TextStyle(color: Colors.blueAccent, fontSize: 20
                            ),
                          ),
                           )
                          ),
                          )
                        ],
                      );
                    }
                  })