Question

我想将复选框小部件的选中状态保存在共享首选项中。这样，当我们再次启动该应用程序时，我们应该会看到选中的列表。

这是代码，但是由于在检查列表中刷新后变为未检查列表，因此无法正常工作。

我已使用SQLite数据库保存“待办事项”列表详细信息。

class _HomeState extends State<Home> {

  TodoService _todoService;
  var _selectedValue;
  var _categories = List<DropdownMenuItem>();

  List<Todo>_todoList=List<Todo>();
  final GlobalKey<ScaffoldState> _globalKey=GlobalKey<ScaffoldState>();




  @override
  initState(){
    super.initState();
    getAllTodos();
    _loadCategories();
    getValues();
  }


  getAllTodos()async{
    _todoService=TodoService();
    _todoList=List<Todo>();

    var todos= await _todoService.readTodo();

    todos.forEach((todo){
      setState(() {
        var model=Todo();
        model.id=todo['id'];
        model.title=todo['title'];
        model.dueDate=todo['dueDate'];
        model.category=todo['category'];
        model.isFinished=todo['isFinished'];
        _todoList.add(model);
      });
    });
  }


  _save(String key,dynamic val)async{
    final SharedPreferences prefs = await SharedPreferences.getInstance();
    prefs.setBool(key,val);
  }
  getValues() async {
    final SharedPreferences prefs = await SharedPreferences.getInstance();
    bool value=prefs.getBool('Checked');
    return value;
  }

      body: ListView.builder(itemCount: _todoList.length,itemBuilder: (context, index){
        return Padding(
          padding:  EdgeInsets.only(top:8.0, left: 8.0, right: 8.0),
          child: Card (
            elevation: 8.0,
            shape: RoundedRectangleBorder(
              borderRadius: BorderRadius.circular(0)
            ),
              child: ListTile(
                leading: Checkbox(
                  checkColor: Colors.indigo,
                  value: _todoList[index].isChecked,
                  onChanged:(bool value){
                      setState(() {
                        _todoList[index].isChecked=value;


                      });
                      _save('Checked',value);

        },

                ),
                title: Row(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                  children: <Widget>[
                    Text(_todoList[index].title ?? 'No Title',
                      style: TextStyle(decoration: (_todoList[index].isChecked? TextDecoration.lineThrough: TextDecoration.none),
                      ),
                    ),
                    IconButton(icon: Icon(Icons.delete,color: Colors.red,
                    ),
                        onPressed: (){
                          _deleteFormDialog(context,_todoList[index].id);
                        }
                    ),
                  ],
                ),
                subtitle: Text(_todoList[index].dueDate ?? 'No Due Date'),
//                  trailing: Text(_todoList[index].dueDate ?? 'No Due Date'),
              ),
          ),
        );
      }),
      floatingActionButton: FloatingActionButton(
        onPressed: ()=>Navigator.of(context).push(MaterialPageRoute(builder:(context)=>TodoScreen())),
        child: Icon(Icons.add),
      ),
    );
  }
}

Answer 1

您不会对在let cell; // is of type Cell let input; // is of type PlayerInput if cell is Player or Metal, FALSE if cell is Boulder(_) or Diamond(_) and input is Down, FALSE if cell is Boulder(NotFalling) and input is Up, FALSE if cell is Boulder(_) and input is Right or Left, and oneMoreCondition(cell,input) is true, FALSE otherwise TRUE中调用的getValues()函数返回的值做任何事情。

initState()

我看到您的复选框的值是从列表中设置的，也许是将值存储在@override initState(){ super.initState(); getAllTodos(); _loadCategories(); getValues(); // This is returning the saved value, either true, false, or null. You must set your checkBox initially to this value. }函数的列表中。

getValues()

getValues() async { final SharedPreferences prefs = await SharedPreferences.getInstance(); bool val = prefs.getBool('Checked'); setState(() { _todoList[0].isChecked = val?? false; }); }是一个空值运算符，如果保存的??是_todoList[0].isChecked，它将false设置为val，如果您不这样做，则会发生这种情况。还没有保存任何东西。

如何在flutter中的共享首选项中保存复选框的状态？

1 个答案: