Android listadapter中未调用DiffCallback
嗨,我正在尝试在我的应用程序中使用listadapter和diffcallback。不知何故,当我做某事时,视图根本不会更新 当我在回调中的“areItemsTheSame”和“areContentsTheSame”中放入一些日志时,根本不会调用它 这是我的主要活动Android listadapter中未调用DiffCallback,android,kotlin,android-recyclerview,Android,Kotlin,Android Recyclerview,嗨,我正在尝试在我的应用程序中使用listadapter和diffcallback。不知何故,当我做某事时,视图根本不会更新 当我在回调中的“areItemsTheSame”和“areContentsTheSame”中放入一些日志时,根本不会调用它 这是我的主要活动 class MainActivity : AppCompatActivity() { private lateinit var recyclerView: RecyclerView private lateinit var vie
class MainActivity : AppCompatActivity() {
private lateinit var recyclerView: RecyclerView
private lateinit var viewAdapter: TodoAdapter
private lateinit var viewManager: RecyclerView.LayoutManager
private lateinit var viewModel : TodoViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val binding: ActivityMainBinding = DataBindingUtil.setContentView(this, R.layout.activity_main)
//viewModel
viewModel = ViewModelProviders.of(this).get(TodoViewModel::class.java)
viewManager = LinearLayoutManager(this)
viewAdapter = TodoAdapter(viewModel.todos)
binding.btnNew.setOnClickListener {
viewModel.todos.value!!.add(Todo(3, binding.newText.text.toString()))
}
recyclerView = binding.myRecyclerView
recyclerView.apply {
layoutManager = viewManager
adapter = viewAdapter
}
viewModel.todos.observe(this, Observer{ list ->
viewAdapter.submitList(list)
Log.i("debug", "im @observe " + list.toString())
})
}
viewModel.todos.observe(this, Observer{ list ->
viewAdapter.submitList(list.toMutableList())
})
}
这是我的适配器
class TodoAdapter(var items: MutableLiveData<ArrayList<Todo>>):
ListAdapter<Todo, TodoAdapter.MyViewHolder>(TodoDiffCallback()) {
// Create new views (invoked by the layout manager)
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
// create a new view
val inflater = LayoutInflater.from(parent.context)
val binding = ListItemBinding.inflate(inflater)
return MyViewHolder(binding)
}
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
holder.todoText.text = getItem(position).task
//delete
holder.delBtn.setOnClickListener {
items.value!!.removeAt(position)
submitList(items.value)
Log.i("debug", "@adapter what is items " + items.value.toString())
}
//override fun getItemCount() = items.value!!.size
class MyViewHolder(val binding: ListItemBinding) : RecyclerView.ViewHolder(binding.root) {
val todoText = binding.todoItem
val delBtn = binding.btnDelete
val ediBtn = binding.btnEdit
}
类ToLoadapter(变量项:MutableLiveData):
ListAdapter(TodoDiffCallback()){
//创建新视图(由布局管理器调用)
重写CreateViewHolder(父级:ViewGroup,viewType:Int):MyViewHolder{
//创建新视图
val inflater=LayoutInflater.from(parent.context)
val binding=ListItemBinding.充气(充气机)
返回MyViewHolder(绑定)
}
覆盖onBindViewHolder(holder:MyViewHolder,位置:Int){
holder.todoText.text=getItem(position).task
//删除
holder.delBtn.setOnClickListener{
items.value!!.removeAt(位置)
submitList(items.value)
Log.i(“debug”,“@adapter what is items”+items.value.toString())
}
//重写fun getItemCount()=items.value!!.size
类MyViewHolder(val绑定:ListItemBinding):RecyclerView.ViewHolder(binding.root){
val todoText=binding.todoItem
val delBtn=binding.btnDelete
val ediBtn=binding.btnEdit
}
}
类TodoDiffCallback:DiffUtil.ItemCallback(){
覆盖乐趣项相同(p0:Todo,p1:Todo):布尔值{
Log.i(“debug”,“here”+p0+“inItems”+p1)
返回p0==p1
}
覆盖乐趣内容相同(p0:Todo,p1:Todo):布尔值{
Log.i(“调试”,“此处”+p0+“inContents”+p1)
返回p0.equals(p1)
}
}
我的视图模型
class TodoViewModel: ViewModel() {
val todos = MutableLiveData<ArrayList<Todo>>()
init{
todos.value = arrayListOf(
Todo(1, "cooking"),
Todo(2, "washing")
)
}
class-TodoViewModel:ViewModel(){
val todos=MutableLiveData()
初始化{
todos.value=arrayListOf(
Todo(1,“烹饪”),
待办事项(2,“清洗”)
)
}
}
不幸的是,android文档没有给出更多的例子
同样,DiffUtil类中的两个“日志”根本没有被调用。当我单击remove按钮时,UI没有更新,但日志显示了正确的结果
感谢当前的工作解决方案 我读过关于“在liveData中观察”的文章,它直到我调用“setValue”方法才被触发 因此,我在ViewModel类中添加了一些新方法,并在其中应用setValue 添加newItem的示例
fun addTodo(text: String) {
_todos.value!!.add(Todo(3, text))
_todos.setValue(_todos.value)
}
到目前为止,它是有效的。我现在只运行一次submitList,在我的observe in Main活动中
class MainActivity : AppCompatActivity() {
private lateinit var recyclerView: RecyclerView
private lateinit var viewAdapter: TodoAdapter
private lateinit var viewManager: RecyclerView.LayoutManager
private lateinit var viewModel : TodoViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val binding: ActivityMainBinding = DataBindingUtil.setContentView(this, R.layout.activity_main)
//viewModel
viewModel = ViewModelProviders.of(this).get(TodoViewModel::class.java)
viewManager = LinearLayoutManager(this)
viewAdapter = TodoAdapter(viewModel.todos)
binding.btnNew.setOnClickListener {
viewModel.todos.value!!.add(Todo(3, binding.newText.text.toString()))
}
recyclerView = binding.myRecyclerView
recyclerView.apply {
layoutManager = viewManager
adapter = viewAdapter
}
viewModel.todos.observe(this, Observer{ list ->
viewAdapter.submitList(list)
Log.i("debug", "im @observe " + list.toString())
})
}
viewModel.todos.observe(this, Observer{ list ->
viewAdapter.submitList(list.toMutableList())
})
我仍然有一个问题,即项目的“位置”仍然不正确。例如:
[更新](通过使用:holder.getAdapterPosition()解决问题)我能看看你的视图模型吗?你确定你的列表确实在变化吗?我昨天和你有同样的问题。那是因为你使用的列表在viewmodel中是相同的索引引用。你可以尝试调试并检查adapter和livedata视图模型中的列表。我的解决方案是从实时数据复制数组,然后用不同的reference@RofieSagara我在上面的问题中添加了它,谢谢,在TODO初始设置后,您并没有真正更改TODO的值。为什么会触发diffutils?