如何解决我的MVVM Room recyclerview杀死应用后刚刚刷新
MainActivity显示一个recyclerview以及一个浮动操作按钮，该意图用于AddActivity，我可以在其中将数据存储到房间数据库中，但是当我保存新数据时，只有在我杀死了应用程序并重新打开，它会显示添加的新数据，不支持livedata观察并注意更改？
主要活动
class MainActivity : AppCompatActivity() {
private lateinit var binding:ActivityMainBinding
private lateinit var clienteViewModel : ClienteViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = DataBindingUtil.setContentView(this,R.layout.activity_main)
val dao = ClienteDataBase.getInstance(application).clienteDAO
val repository = ClienteRespository(dao)
val factory = ClienteVIewModelFactory(repository)
clienteViewModel = ViewModelProvider(this,factory).get(ClienteViewModel::class.java)
binding.viewModel = clienteViewModel
binding.lifecycleOwner = this
displayRecyclerview()
val fab: View = findViewById(R.id.fab)
fab.setOnClickListener { view ->
Snackbar.make(view,"Here's a Snackbar",Snackbar.LENGTH_LONG)
.setAction("Action",null)
.show()
val intent = Intent(this@MainActivity,NewItemActivity::class.java)
startActivity(intent)
}
}
private fun displayRecyclerview(){
binding.clientesRecyclerView.layoutManager = LinearLayoutManager(this)
displayListaClientes()
}
private fun displayListaClientes(){
clienteViewModel.cliente.observe(this,Observer {
Log.i("mYtAG",it.toString() )
binding.clientesRecyclerView.adapter = RecyclerViewAdapter(it)
})
}
}
添加数据的活动
class NewItemActivity：AppCompatActivity（）{
private lateinit var binding:ActivityNewItemBinding
private lateinit var clienteViewModel : ClienteViewModel
companion object {
val ITEM_NAME = "new_item_activity.item_name"
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = DataBindingUtil.setContentView(this,R.layout.activity_new_item)
val dao = ClienteDataBase.getInstance(application).clienteDAO
val repository = ClienteRespository(dao)
val factory = ClienteVIewModelFactory(repository)
clienteViewModel = ViewModelProvider(this,factory).get(ClienteViewModel::class.java)
binding.viewModel = clienteViewModel
binding.lifecycleOwner = this
}
// As an alternative to 'setCanceledOnTouchOutside(false)' method.
override fun onTouchEvent(event: MotionEvent): Boolean = true
}
ViewModel
Class ClienteViewModel（私有val储存库：ClienteRespository）：ViewModel（），可观察{
val cliente : LiveData<List<Cliente>> = repository.cliente
@Bindable
val inputNome = MutableLiveData<String>()
@Bindable
val inputProduto = MutableLiveData<String>()
@Bindable
val inputValor = MutableLiveData<String>()
@Bindable
val saveOrupdateBtn = MutableLiveData<String>()
@Bindable
val deleteAllBtn = MutableLiveData<String>()
init {
saveOrupdateBtn.value = "Save"
deleteAllBtn.value = "Clear ALl"
}
fun saveOrUpdate() {
val nome: String = inputNome.value!!
val produto: String = inputProduto.value!!
val valor: String = inputValor.value!!
insertCliente(Cliente(0,nome,produto,valor))
inputNome.value = null
inputProduto.value = null
inputValor.value = null
}
fun clearOrDelete() {
deleteAllCliente()
}
private fun insertCliente(cliente: Cliente) = viewModelScope.launch {
repository.insert(cliente)
}
fun upDateCliente(cliente: Cliente) = viewModelScope.launch {
repository.update(cliente)
}
fun deleteCliente(cliente: Cliente) = viewModelScope.launch {
repository.delete(cliente)
}
fun deleteAllCliente() = viewModelScope.launch {
repository.deleteAll()
}
override fun removeOnPropertyChangedCallback(callback: Observable.OnPropertyChangedCallback?) {
}
override fun addOnPropertyChangedCallback(callback: Observable.OnPropertyChangedCallback?) {
}
}
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