当我的列表为空时如何显示图像或文本？

Question

我是颤振的新手我想显示一个图像或文本，就像No Record Found我从 listView 或 listView 中删除所有项目一样是空的。在 Android 中，我用于setEmptyView()这种情况，但我不知道如何在颤振中做到这一点。目前我正在通过 ListCan有人帮我吗？

  DatabaseHelper databaseHelper = DatabaseHelper();
  List<TaskModel> list;
  int count = 0;
  TaskModel taskModel;

  @override
  Widget build(BuildContext context) {
    if (list == null) {
      list = List<TaskModel>();
      updateListView();
    }
    return Scaffold(
      appBar: AppBar(
        title: Text('Task'),
      ),
      floatingActionButton: FloatingActionButton(
          backgroundColor: Colors.purple,
          child: Icon(Icons.add),
          onPressed: () {
            Navigator.push(context,
                new MaterialPageRoute<void>(builder: (context) {
                  return new CreateTask(TaskModel('', '', '', '', '', '', ''),'Add Task');
                }));
          }),
      body: getTasListView()
    );
  }

  ListView getTasListView(){
    return ListView.builder(
        itemCount: count,
        itemBuilder: (BuildContext context, int position){
          return Card(
            color: Colors.white,
            elevation: 2.0,
            child: Column(
              children: <Widget>[
                ListTile(
                  title: Text(this.list[position].task),
                  onLongPress: () => navigateToDetail(this.list[position],'Edit Task'),
                )
              ],
            ),
          );
        }
    );
  }
}

Answer 1

检查长度或数组并决定返回哪个小部件。

   Widget getTasListView() {
        return arrList.isNotEmpty
            ? ListView.builder(
                itemCount: arrList.length,
                itemBuilder: (BuildContext context, int position) {
                  return Card(
                    color: Colors.white,
                    elevation: 2.0,
                    child: Column(
                      children: <Widget>[
                        ListTile(
                          title: Text(this.list[position].task),
                          onLongPress: () =>
                              navigateToDetail(this.list[position], 'Edit Task'),
                        )
                      ],
                    ),
                  );
                })
            : Center(child: Image.asset("path/image/img.png"));
      }

并使用arrList.length代替itemCount: count.