Question

问题：单击一个复选框仅会删除位于回收站视图位置[0]的第一个项目（卡片视图）。如果我单击另一个具有不同位置的复选框，则该项目不会被删除。

我尝试的方法：我创建了一个界面来监听click事件处理程序。我得到了适配器的位置，并将其传递给我的点击监听器。我还尝试使用Lamba，并尝试在适配器构造函数内部传递click监听器。*

我希望发生的事情：单击复选框后，具有该位置的项目（卡片视图）将被删除。

适配器类

 class ListAdapter(
    private val callback: AdapterCallBack

) :
    RecyclerView.Adapter<ListAdapter.MyViewHolder>() {

    private var todoList: List<TodoItem> = ArrayList()

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
        val context = parent.context
        val view = LayoutInflater.from(context).inflate(
            R.layout.item_list, parent, false
        )
        return MyViewHolder(view)
    }

    override fun getItemCount(): Int {
        return todoList.size
    }

    override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
        val currentItem = todoList[position]
        holder.itemView.tvTitle.text = currentItem.title
        holder.itemView.dueDate.text = currentItem.dueDate
        holder.bind(currentItem)
    }

    fun setList(todo: List<TodoItem>) {
        this.todoList = todo
        notifyDataSetChanged()

    }

    inner class MyViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {

        fun bind(todoItem: TodoItem) {
            val position = adapterPosition

            itemView.setOnClickListener() {
                callback.onItemClick(todoItem, position)
            }
            itemView.doneCheckBox.setOnClickListener() {
                callback.onCheckBoxClick(todoItem, position)
            }
        }
    }


}

界面


 interface AdapterCallBack {
 fun onCheckBoxClick(todoItem: TodoItem, position: Int)

 fun onItemClick(todoItem: TodoItem, position: Int)

}

MainFragment（实现接口）


    class MainFragment : Fragment(), AdapterCallBack {
            private lateinit var todoViewModel: TodoViewModel
            private lateinit var adapter : ListAdapter
            
        override fun onCreateView(
            inflater: LayoutInflater, container: ViewGroup?,
            savedInstanceState: Bundle?
        ): View? {
            val view = inflater.inflate(R.layout.fragment_main, container, false)
            val recyclerView = view.recyclerview
           // checkDone  = view.findViewById<CheckBox>(R.id.doneCheckBox)
          adapter =
                ListAdapter(this)
            recyclerView.adapter = adapter
            recyclerView.layoutManager = LinearLayoutManager(requireContext())
            todoViewModel = ViewModelProvider(this).get(TodoViewModel::class.java)
            todoViewModel.getAllTodoItems.observe(viewLifecycleOwner, Observer {
                adapter.setList(it)
                Log.i("list", "$it")
            })
            view.fabBtn.setOnClickListener {
                findNavController().navigate(R.id.action_mainFragment_to_detailFragment)
                (activity as AppCompatActivity?)!!.supportActionBar!!.title = "Create"
                Log.i("fab_btn", "Fab button is pressed")
            }
    
            return view
        }
    
        override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
            inflater.inflate(R.menu.delete_all, menu)
    
            super.onCreateOptionsMenu(menu, inflater)
        }
    
        override fun onOptionsItemSelected(item: MenuItem): Boolean {
            when (item.itemId) {
                R.id.delete_all_items -> {
                    todoViewModel.deleteAllItems()
                    Toast.makeText(requireContext(), "All items deleted", Toast.LENGTH_SHORT).show()
                    return true
                }
            }
    
            return super.onOptionsItemSelected(item)
        }
        override fun onCreate(savedInstanceState: Bundle?) {
            super.onCreate(savedInstanceState)
            setHasOptionsMenu(true)
        }
        override fun onCheckBoxClick(todoItem: TodoItem, position: Int) {
            if (doneCheckBox.isChecked) {
                todoViewModel.deleteItem(todoItem)
                Toast.makeText(
                    requireContext(),
                    "Item deleted at position $position is click!",
                    Toast.LENGTH_SHORT
                ).show()
                Log.i("check_click", "$todoItem is deleted at position $position")
            }
        }
        override fun onItemClick(todoItem: TodoItem, position: Int) {
            val action = MainFragmentDirections.actionMainFragmentToDetailFragment(todoItem)
            findNavController().navigate(action)
            Log.i("cardview_click", "Card view  item $todoItem is click at position $position")
        }
    }

ViewModel类

class TodoViewModel(application: Application) : AndroidViewModel(application) {
    val getAllTodoItems: LiveData<List<TodoItem>>
    private val repository: TodoRepository
    private val selectedDate: MutableLiveData<String> = MutableLiveData()
    private val selectedTime: MutableLiveData<String> = MutableLiveData()
    val date: LiveData<String>
        get() = selectedDate
    val time: LiveData<String>
        get() = selectedTime

    init {
        val todoDao = TodoDatabase.getDatabase(application).todoDao
        repository = TodoRepository(dao = todoDao)
        getAllTodoItems = repository.todoItems
    }

    fun insertItem(todoItem: TodoItem) {
        viewModelScope.launch(Dispatchers.IO) {
            repository.insert(todoItem)
        }
    }
    fun updateItem(todoItem: TodoItem) {
        viewModelScope.launch(Dispatchers.IO) {
            repository.update(todoItem)
        }

    }

    fun deleteItem(todoItem: TodoItem) {
        viewModelScope.launch(Dispatchers.IO) {
            repository.delete(todoItem)
        }
    }

    fun deleteAllItems() {
        viewModelScope.launch(Dispatchers.IO) {
            repository.deleteAll()

        }
    }

    fun setDateCalenderValue(date: String) {
        selectedDate.value = date
    }

    fun setTimePickerValue(time: String) {
        selectedTime.value = time
    }
}

Answer 1

您需要通知适配器哪一行已被删除

将您的onCheckBoxClick函数实现更改为此

        override fun onCheckBoxClick(todoItem: TodoItem, position: Int) {
            if (doneCheckBox.isChecked) {
                todoViewModel.deleteItem(todoItem)
                adapter.notifyItemRemoved(position) // Add this line
                Toast.makeText(
                    requireContext(),
                    "Item deleted at position $position is click!",
                    Toast.LENGTH_SHORT
                ).show()
                Log.i("check_click", "$todoItem is deleted at position $position")
            }
        }

如何通过复选框删除recyclerview项目？

1 个答案: