dart

问题 Container( child: Text( 'This is a Container', textScaleFactor: 2, style: TextStyle(color: Colors.black), ), decoration: BoxDecoration( borderRadius: BorderRadius.circular(10), color: Colors.white, border: Border( left: BorderSide( color: Colors.green, width: 3, ), ), ), height: 50, ), This is supposed to show a rounded-edged container with a green left border 3px wide, and the child Text "This is a Container". However, it just shows a rounded-edged container with an invisible child and an

问题 Container( child: Text( 'This is a Container', textScaleFactor: 2, style: TextStyle(color: Colors.black), ), decoration: BoxDecoration( borderRadius: BorderRadius.circular(10), color: Colors.white, border: Border( left: BorderSide( color: Colors.green, width: 3, ), ), ), height: 50, ), This is supposed to show a rounded-edged container with a green left border 3px wide, and the child Text "This is a Container". However, it just shows a rounded-edged container with an invisible child and an

问题 Container( child: Text( 'This is a Container', textScaleFactor: 2, style: TextStyle(color: Colors.black), ), decoration: BoxDecoration( borderRadius: BorderRadius.circular(10), color: Colors.white, border: Border( left: BorderSide( color: Colors.green, width: 3, ), ), ), height: 50, ), This is supposed to show a rounded-edged container with a green left border 3px wide, and the child Text "This is a Container". However, it just shows a rounded-edged container with an invisible child and an

问题 Container( child: Text( 'This is a Container', textScaleFactor: 2, style: TextStyle(color: Colors.black), ), decoration: BoxDecoration( borderRadius: BorderRadius.circular(10), color: Colors.white, border: Border( left: BorderSide( color: Colors.green, width: 3, ), ), ), height: 50, ), This is supposed to show a rounded-edged container with a green left border 3px wide, and the child Text "This is a Container". However, it just shows a rounded-edged container with an invisible child and an

问题 Container( child: Text( 'This is a Container', textScaleFactor: 2, style: TextStyle(color: Colors.black), ), decoration: BoxDecoration( borderRadius: BorderRadius.circular(10), color: Colors.white, border: Border( left: BorderSide( color: Colors.green, width: 3, ), ), ), height: 50, ), This is supposed to show a rounded-edged container with a green left border 3px wide, and the child Text "This is a Container". However, it just shows a rounded-edged container with an invisible child and an

问题 Container( child: Text( 'This is a Container', textScaleFactor: 2, style: TextStyle(color: Colors.black), ), decoration: BoxDecoration( borderRadius: BorderRadius.circular(10), color: Colors.white, border: Border( left: BorderSide( color: Colors.green, width: 3, ), ), ), height: 50, ), This is supposed to show a rounded-edged container with a green left border 3px wide, and the child Text "This is a Container". However, it just shows a rounded-edged container with an invisible child and an

问题 How do you sort a List in dart based on a bool value, the compareTo method doesn't work with bool . I want true values to appear at the top of the list. 回答1: You can define you own compare function for bool and pass it to the sort method of List . Example with booleans as your bool List : booleans.sort((a, b) { if(b) { return 1; } return -1; }); This example tells the sort method that true elements should be sorted higher than false elements. 来源： https://stackoverflow.com/questions/62031301

问题 How do you sort a List in dart based on a bool value, the compareTo method doesn't work with bool . I want true values to appear at the top of the list. 回答1: You can define you own compare function for bool and pass it to the sort method of List . Example with booleans as your bool List : booleans.sort((a, b) { if(b) { return 1; } return -1; }); This example tells the sort method that true elements should be sorted higher than false elements. 来源： https://stackoverflow.com/questions/62031301

问题 I am updating my old flutter code with the new FlutterFire API. I use a setData with merge: true in one of my functions to update some document fields that are saved in a Map. I do change setData to set , but I get an error with the new FlutterFire plugin that "merge" isn't defined. I found in the migration docs that setData/set now supports SetOptions to merge data/fields (previously this accepted a Map) The document reference also says: /// If [SetOptions] are provided, the data will be

问题 In Flutter we use async await and Future, can someone explain that if we don't use another thread (which we can't in dart) and run the job on main UIThread only won't the app become choppy because even if we are waiting for the job to execute it will ultimately execute on UIThread only. I somewhere read about isolates also. But cannot paint the exact picture. If someone can explain in detail. 回答1: I think you missed something in asynchronous methods in Dart. Dart is a single threaded