在我看来,当我使用viewModel
时,我应该添加binding.lifecycleOwner=this
。
我发现很多项目如代码A不加binding.lifecycleOwner=this
,为什么?
代码 A 来自项目 https://github.com/enpassio/Databinding
代码 A
class AddToyFragment : androidx.fragment.app.Fragment() {
private lateinit var binding: AddToyBinding
...
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
binding = DataBindingUtil.inflate(
inflater, R.layout.fragment_add_toy, container, false
)
setHasOptionsMenu(true)
return binding.root
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
(requireActivity() as AppCompatActivity).supportActionBar?.setDisplayHomeAsUpEnabled(true)
//If there is no id specified in the arguments, then it should be a new toy
val chosenToy : ToyEntry? = arguments?.getParcelable(CHOSEN_TOY)
//Get the view model instance and pass it to the binding implementation
val factory = AddToyViewModelFactory(provideRepository(requireContext()), chosenToy)
mViewModel = ViewModelProviders.of(this, factory).get(AddToyViewModel::class.java)
binding.viewModel = mViewModel
binding.fab.setOnClickListener {
saveToy()
}
binding.lifecycleOwner=this //I think it should add
}
binding.lifecycleOwner
用于观察具有数据绑定的LiveData
。 有点android:text=@{viewModel.text}
val text:LiveData<String>
的地方。视图将在运行时观察文本更改。
据我所知,
绑定.生命周期所有者= 这个
一端用于订阅以在 liveData 更改时接收消息(因此视图中的信息保持一致(,另一端用于在视图和片段被销毁时从列表中删除观察者(以防止内存泄漏(。片段的视图生命周期所有者更适合以这种方式作为生命周期所有者进行绑定,不是吗?