我正在使用Android Jetpack导航,MVVM和dataBinding,并且遇到了一个问题。每当我从详细信息片段导航回来时,我的主List片段都会刷新(再次调用API,并再次绘制recyclerList)。我该如何预防?
这是主列表片段代码:
class PostListFragment : BaseFragment() {
private lateinit var viewModel: PostListViewModel
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val binding = TestFragmentBinding.inflate(inflater, container, false)
val factory = InjectorUtils.providePostListViewModelFactory()
viewModel = ViewModelProviders.of(this, factory).get(PostListViewModel::class.java)
val adapter = MainListAdapter()
binding.mainList.adapter = adapter
binding.let {
it.viewmodel = viewModel
it.setLifecycleOwner(this@PostListFragment)
}
subscribeUi(adapter)
return binding.root
}
private fun subscribeUi(adapter: MainListAdapter) {
viewModel.progressVisible.postValue(true)
addToDisposable(viewModel.getContentRepository().getAllPosts(requireContext())
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe({ result ->
viewModel.progressVisible.postValue(false)
adapter.submitList(result)
}, { error ->
viewModel.progressVisible.postValue(false)
}))
}
}
我还要补充一点,我正在MainFragment上使用此片段,其中包含viewPager。
我的MainFragment代码:
class MainFragment : Fragment() {
private lateinit var sharedViewModel: SharedNewPostViewModel
private lateinit var viewModel: MainViewModel
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val binding = MainFragmentBinding.inflate(inflater, container, false)
val factory = InjectorUtils.provideMainViewModelFactory()
viewModel = ViewModelProviders.of(this, factory).get(MainViewModel::class.java)
binding.let {
it.viewModel = viewModel
it.setLifecycleOwner(this@MainFragment)
}
sharedViewModel = activity?.run {
ViewModelProviders.of(this).get(SharedNewPostViewModel::class.java)
} ?: throw Exception("Invalid activity")
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val pagerAdapter = MainPagerAdapter(childFragmentManager)
viewPager.adapter = pagerAdapter
tabLayout.setupWithViewPager(viewPager)
}
}
最佳答案
需要先检查savedInstanceState
中的Activity.onCreate()
:
if(savedInstanceState == null) {
...
}
并且当它不是
null
时,请不要给Fragment
充气-以后不会再调用Fragment.onCreateView()
两次(否则很难从那里返回View
)。
关于android - 如何防止在背面 fragment 导航中再次设置 View 模型,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/54519452/