小编yug*_*g k的帖子

我想将两个数组转换为字典。我有两个动态列表，之后我需要将两个列表合并为字典（地图）

var x = ["car", "train", "bus"];
var y = ["https://car", "https://train", "https://bus"]

Expected:
 final Map<String, String> z = ["car": "https://car", "train": "https://train", "bus": "https://bus"];

我需要在标签栏视图的应用栏中添加后退按钮。

当您将标签栏视图控制器推送到导航堆栈时，我无法在标签菜单的应用栏中看到后退按钮。当我从左向右滑动时，我将转到上一个屏幕，但在应用栏中看不到后退按钮

下面是我如何将标签栏推入导航堆栈

Navigator.push(
                context,
                MaterialPageRoute(
                    builder: (context) => TabBarScreen()),
              );


class TabBarScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: DefaultTabController(
        length: 3,
        child: Scaffold(
          appBar: AppBar(
            bottom: TabBar(
              tabs: [
                Tab(icon: Icon(Icons.directions_car)),
                Tab(icon: Icon(Icons.directions_transit)),
                Tab(icon: Icon(Icons.directions_bike)),
              ],
            ),
            title: Text('Tabs Demo'),
            automaticallyImplyLeading: true,

          ),
          body: TabBarView(
            children: [
              Icon(Icons.directions_car),
              Icon(Icons.directions_transit),
              Icon(Icons.directions_bike),
            ],
          ),
        ),
      ),
    );
  }
}