如何根据文本字段上的输入更改按钮的文本

我有一个带有“删除”按钮的小弹出窗口，但是每当输入文本不同于0.00时，我都想将文本更改为“卖”

showDialog( context: context, builder: (context) { String _popUpDeleteSoldText = "Delete"; return AlertDialog( title: Text("Delete " + doc['propertyName'] + "?"), content: Container( height: 120, child: Column( children: [ TextField( onChanged: (text) { if (text != "0.00") { print("i'm != 0.00"); setState(() { //TODO - THIS AIN'T WORKING _popUpDeleteSoldText = "Sell"; }); } else { print("i'm still 0"); setState(() { _popUpDeleteSoldText = "Delete"; }); } }, 按钮：

MaterialButton( elevation: 4.0, child: Text( _popUpDeleteSoldText, style: TextStyle(color: Colors.white), ) .... 打印正在使用onChange函数，但是按钮文本始终显示为“删除”