我有一个ActionBar打开CategoryFragment. 该片段接受从另一个片段传递的category对象参数。SafeArgs在 中CategoryFragment，我将category的名称和 idViewModel作为SavedStateHandle值存储到片段的共享中。我已经对其进行了设置，以便片段在SavedStateHandle需要时使用存储的类别名称和 id 值。例如，第一次CategoryFragment使用从发送片段传递的类别对象，但随后的创建CategoryFrgament将使用这些SavedStateHandle值。
问题是，如果在第一次打开CategoriesFragment然后通过按手机的物理后退按钮或从导航栏中手机的最近按钮终止应用程序退出应用程序后，现在CategoryFragment通过按操作栏菜单图标直接打开应用程序会显示一个空白屏幕。这是因为从返回的值SavedStateHandle是空的。我怎样才能解决这个问题？
类别片段
class CategoryFragment : Fragment(), SearchView.OnQueryTextListener {
lateinit var navController: NavController
private var adapter: TasksRecyclerAdapter? = null
private val viewModel: CategoryTasksViewModel by activityViewModels()
private var fromCategoriesFragment: Boolean = false
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_category, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
navController = Navigation.findNavController(view)
observerSetup()
recyclerSetup()
var searchView = category_tasks_searchview
searchView.setOnQueryTextListener(this)
fab_new_task.setOnClickListener {
navController.navigate(R.id.action_categoryFragment_to_newTaskDialogFragment)
}
showTasks()
}
private fun showTasks() {
if(fromCategoriesFragment){
PomoPlayObservablesSingleton.fromCategoriesFragment.onNext(false)
if (!arguments?.isEmpty!!) {
var args = CategoryFragmentArgs.fromBundle(arguments!!)
category_title.text = args.category?.name
var category = args.category
viewModel.setPomoCategoryName(category.name)
viewModel.setCategoryId(category.id)
viewModel.searchTasksByCategoryId(category.id)
}
}
else{
category_title.text = viewModel.getPomoCategoryName()
viewModel.searchTasksByCategoryId(viewModel.getCategoryId())
Log.i("CategoryFrag-CatName", viewModel.getPomoCategoryName().toString())
Log.i("CategoryFrag-CatId", viewModel.getCategoryId().toString())
}
}
private fun observerSetup() {
viewModel.getSearchTasksByCategoryIdResults().observe(this,androidx.lifecycle.Observer { tasks ->
if(tasks.isNotEmpty()){
adapter?.setTasksList(tasks.sortedBy { task -> task.name?.toLowerCase() })
task_not_found_bubble.visibility = View.GONE
task_not_found_text.visibility = View.GONE
}
else{
task_not_found_bubble.visibility = View.VISIBLE
task_not_found_text.visibility = View.VISIBLE
}
})
PomoPlayObservablesSingleton.fromCategoriesFragment.subscribe {value -> fromCategoriesFragment = value}
}
private fun recyclerSetup() {
adapter = context?.let { TasksRecyclerAdapter(it) }
tasks_list?.layoutManager = LinearLayoutManager(context)
tasks_list?.adapter = adapter
}
override fun onQueryTextSubmit(query: String?): Boolean {
Log.i("Lifecycle-CatFragment", "onQueryTextSubmit() called")
var q = query?.toLowerCase()?.trim()?.replace("\\s+".toRegex(), " ")
setLastSearchQuery(q.toString())
viewModel.searchTasksByName(viewModel.getLastSearchQuery().toString())
return false
}
private fun setLastSearchQuery(lastSearchQuery: String) {
viewModel.setLastSearchQuery(lastSearchQuery)
}
}
CategoryTasksViewModel
class CategoryTasksViewModel(application: Application, state: SavedStateHandle) : AndroidViewModel(application) {
private val repository: PomoPlayRepository = PomoPlayRepository(application)
private val allCategories: LiveData<List<Category>>?
private val allPomoTasks: LiveData<List<PomoTask>>?
private val searchCategoriesByNameResults: MutableLiveData<List<Category>>
private val searchCategoryByIdResults: MutableLiveData<Category>
private val searchTasksByIdResults: MutableLiveData<PomoTask>
private val searchTasksByNameResults: MutableLiveData<List<PomoTask>>
private val searchTasksByCategoryIdResults: MutableLiveData<List<PomoTask>>
private val savedStateHandle = state
companion object{
private const val LAST_SEARCH_QUERY = "lastSearchQuery"
}
init {
allCategories = repository.allCategories
allPomoTasks = repository.allPomoTasks
searchTasksByIdResults = repository.searchTasksByIdResults
searchTasksByNameResults = repository.searchTasksByNameResults
searchTasksByCategoryIdResults = repository.searchTasksByCategoryIdResults
searchCategoryByIdResults = repository.searchCategoriesByIdResults
searchCategoriesByNameResults = repository.searchCategoriesByNameResults
}
fun setLastSearchQuery(lastSearchName: String){
savedStateHandle.set(LAST_SEARCH_QUERY, lastSearchName)
}
fun getLastSearchQuery(): String?{
return savedStateHandle.get<String>(LAST_SEARCH_QUERY)
}
fun setPomoCategoryName(name: String?){
savedStateHandle.set("categoryName", name)
}
fun getPomoCategoryName(): String?{
return savedStateHandle.get<String>("categoryName")
}
fun setCategoryId(id: Int){
savedStateHandle.set("categoryId", id)
}
fun getCategoryId(): Int?{
return savedStateHandle.get<Int>("categoryId")
}
fun insertTask(pomoTask: PomoTask?) {
repository.insertTask(pomoTask)
}
fun deleteTask(pomoTask: PomoTask) {
repository.deleteTask(pomoTask)
}
fun updateTask(pomoTask: PomoTask) {
repository.updateTask(pomoTask)
}
fun searchTasksByName(name: String) {
repository.searchTasksByName(name)
}
fun searchTasksById(pomoTaskId: Int){
repository.searchTasksById(pomoTaskId)
}
fun searchTasksByCategoryId(categoryId: Int?){
repository.searchTasksByCategoryId(categoryId)
}
fun getAllPomoTasks() : LiveData<List<PomoTask>>? {
return allPomoTasks
}
fun getSearchTasksbyNameResults() : MutableLiveData<List<PomoTask>> {
return searchTasksByNameResults
}
fun getSearchTasksByIdResults() : MutableLiveData<PomoTask> {
return searchTasksByIdResults
}
fun getSearchTasksByCategoryIdResults() : MutableLiveData<List<PomoTask>> {
return searchTasksByCategoryIdResults
}
}