Question

为什么底部导航栏标题不显示？它应该显示在图标下方

class FlutterProject extends StatefulWidget {
  final String title = "Flutter Bottom Tab demo";

  @override
  GoalsListState createState() {
    return GoalsListState();
  }
}

class GoalsListState extends State<FlutterProject>
    with SingleTickerProviderStateMixin {
  int _cIndex = 0;

  void _incrementTab(index) {
    setState(() {
      _cIndex = index;
    });
  }

  final List<Widget> _children = [
    new One(),
    new Two(),
    new Three(),
    new Four(),
    new More()
  ];

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
        body: _children[_cIndex],
        bottomNavigationBar: BottomNavigationBar(
          currentIndex: _cIndex,
          type: BottomNavigationBarType.shifting,
          items: [
            BottomNavigationBarItem(
                icon:
                    Icon(Icons.graphic_eq, color: Color.fromARGB(255, 0, 0, 0)),
                title: new Text('One')),
            BottomNavigationBarItem(
                icon: Icon(Icons.report_problem,
                    color: Color.fromARGB(255, 0, 0, 0)),
                title: new Text('Two')),
            BottomNavigationBarItem(
                icon: Icon(Icons.work, color: Color.fromARGB(255, 0, 0, 0)),
                title: new Text('Three')),
            BottomNavigationBarItem(
                icon: Icon(Icons.domain, color: Color.fromARGB(255, 0, 0, 0)),
                title: new Text('Four')),
            BottomNavigationBarItem(
                icon: Icon(Icons.menu, color: Color.fromARGB(255, 0, 0, 0)),
                title: new Text('Five')),
          ],
          onTap: (index) {
            _incrementTab(index);
          },
        ));
  }
}

我在这里想念什么？

Answer 1

如果提供了3个以上的BottomNavigationBar项目，但类型未指定，则根据https://docs.flutter.io/flutter/material/BottomNavigationBar/BottomNavigationBar.html更改为BottomNavigationBarType.shifting。这些信息应在课程文档中突出显示。很容易忽略它在哪里（我忽略了它）。

添加类型：BottomNavigationBarType。已固定在BottomNavigationBar上

BottomNavigationBar(
   type: BottomNavigationBarType.fixed,
   items: <BottomNavigationBarItem>[],
)

Answer 2

项目的长度必须至少为两个，并且每个项目的图标和标题不能为空。

如果type为null，则当有两个或三个项目时使用BottomNavigationBarType.fixed，否则使用BottomNavigationBarType.shifting。

如果您想每次都显示标题，请添加类型：BottomNavigationBarType.fixed,

 bottomNavigationBar: BottomNavigationBar(
   type: BottomNavigationBarType.fixed,
   currentIndex: _page,
   items: tabsList,
 )

如果只希望标题位于“选定”选项卡上，则像这样添加到showSelectedLabels: true,和showUnselectedLabels: false,，

 bottomNavigationBar: BottomNavigationBar(
   type: BottomNavigationBarType.fixed,
   showSelectedLabels: true,
   showUnselectedLabels: false,
   currentIndex: _page,
   items: tabsList,
 )

Answer 3

确实显示了标题，但如果您仔细观察，则标题颜色为white。只需在文本中添加color即可正确显示它。

title: new Text('One', style: TextStyle(color: Colors.black))

Answer 4

你应该使用这个代码：

bottomNavigationBar: BottomNavigationBar(
//use both properties
   type: BottomNavigationBarType.fixed,
   showUnselectedLabels: true,
//-----------
    items: const <BottomNavigationBarItem>[
    BottomNavigationBarItem(
      icon: Icon(Icons.icon1),
      label:'item 1',
   ),
   BottomNavigationBarItem(
     icon: Icon(Icons.icon2),
     label: 'item 2',
   ),
 ],
)

Answer 5

这里有一个简单的技巧来显示导航栏项目的标签

 BottomNavigationBarItem(
            icon: Column(
              children: [
                new Icon(widget.currentTab == 2 ? Icons.dashboard_outlined : Icons.dashboard_outlined),
                Text("Homes")
              ],
            ),
            label: 'Home',

          ),

BottomNavigationBar标题未显示在Flutter中

5 个答案: