Develop Reference

custome layout in HeadersSupportFragment whit leanback

I have just started working with leanback. I want to add my custom layout to this class.please help me...
`class CustomHeadersFragment: HeadersSupportFragment(),OnHeaderClickedListener {
lateinit var adapter: ArrayObjectAdapter
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
// customSetBackground(R.color.fastlane_background)
setOnHeaderClickedListener(this)
setHeaderAdapter()
presenterSelector
}
private fun setHeaderAdapter() {
adapter = ArrayObjectAdapter()
val fragments: LinkedHashMap<Int, CustomRowsFragment> =
(activity as MainActivity?)?.getFragments()!!
var id = 0
for (i in 0 until fragments.size) {
val header = HeaderItem(id.toLong(), "Category $i")
val innerAdapter = ArrayObjectAdapter()
innerAdapter.add(fragments[i])
adapter.add(id, ListRow(header, innerAdapter))
id++
}
setAdapter(adapter)
}`
this is my rows fragment
`class CustomRowsFragment : RowsSupportFragment() {
private var rowsAdapter: ArrayObjectAdapter? = null
private var cardPresenter: Presenter? = null
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val v = super.onCreateView(inflater, container, savedInstanceState)
return v
}`

What is a view model and how can I use it to replace findViewById with View Binding and

I am working on a basic bluetooth app in android studio and I am having trouble with view binding. So far I have this in my MainActivity.kt
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
...
Later in the onCreate I have this line
val btnONOFF = findViewById<View>(R.id.btnONOFF) as Button
and I would like to replace the findViewById using viewbinding but I'm not sure what to replace that line with.
The android developers website says to use something like this
binding.name.text = viewModel.name
but I'm also not sure what a viewModel is.
Here is my ViewFragment.kt incase that is helpful
class ViewFragment : Fragment() {
private var _binding: ActivityMainBinding? = null
private val binding get() = _binding!!
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): RelativeLayout {
_binding = ActivityMainBinding.inflate(inflater, container, false)
return binding.root
}
override fun onDestroyView() {
super.onDestroyView()
_binding = null
}}
Any help is appreciated, thanks!

You can find the tutorial of viewmodel from here.
ViewFragment.kt
class ViewFragment : Fragment() {
private var _binding: ActivityMainBinding? = null
private val binding get() = _binding!!
private val viewModel by viewModel<ActivityViewModel>()
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): RelativeLayout {
_binding = ActivityMainBinding.inflate(inflater, container, false)
setupView()
return binding.root
}
private fun setupView(){
binding.text = viewModel.name
}
override fun onDestroyView() {
super.onDestroyView()
_binding = null
}
}
You can customise your ActivityViewModel.kt
class ActivityViewModel : ViewModel() {
val name = "Hello"
}
Note: by viewModel is koin injection.

Android : Acces parent fragment function from child fragment

I have a Parent Fragment in an activity and have a Child Fragment in Parent Fragment. The NavGraphs of the two Fragments are different. I want to access the function in the Parent Fragment from the Child Fragment, but the application crashes. How can I do it?
Child Fragment:
class ProfilinMenu : Fragment(){
private var _binding : FragmentProfilinMenuBinding? = null
private val profilinmenubinding get() = _binding!!
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,savedInstanceState: Bundle?): View {
_binding = FragmentProfilinMenuBinding.inflate(inflater,container,false)
(parentFragment as Parent).changeName() // this is for access parent
return profilinmenubinding.root
}}
Parent Fragment:
public class Parent : Fragment() {
private var _binding : FragmentParentBinding? = null
private val parentBinding get() = _binding!!
private var instance: Parent? = null
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
_binding = FragmentParentBinding.inflate(inflater, container, false)
val view = parentBinding.root
return view
}
public fun changeName(){
parentBinding.profilinIsmin.text = "Merhaba"
}

Try this..
NavHostFragment navHostFragment = (NavHostFragment) getParentFragment();
ParentFragment parent = (ParentFragment) navHostFragment.getParentFragment();
parent.changeName()

Accessing view of parent fragment from a child fragment connected by viewpager

I have a fragment which happens to be the host fragment with a view pager to three other fragment. I want to access the view pager in the parent fragment from the children so I can manage the currentItem property on button click but using parentFragment is not working.
Parent Fragment
class ClientFragment : DaggerFragment() {
lateinit var adapter: ViewPagerAdapter
private lateinit var nextBtn: Button
private lateinit var progressBar: ProgressBar
private val title by lazy {
getName()
}
val clientManagementViewPager by lazy {
(client_management_included_viewPager as? ViewPager2)
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_client, container, false)
}
override fun onResume() {
super.onResume()
setupViewPager()
val toolbar = (client_management_toolbar as Toolbar)
toolbar.setTitleTextColor(
ContextCompat.getColor(
requireContext(),
R.color.colorPrimaryDark
)
)
val navController = Navigation.findNavController(client_management_appBar)
NavigationUI.setupWithNavController(toolbar, navController)
nextBtn = client_account_next_btn2.findViewById(R.id.btn)
progressBar = client_account_next_btn2.findViewById(R.id.progress_bar)
val nextBtnBackground =
ContextCompat.getDrawable(requireContext(), R.drawable.rounded_corner_background)
nextBtnBackground?.colorFilter = PorterDuffColorFilter(
ContextCompat.getColor(requireContext(), R.color.colorPrimary),
PorterDuff.Mode.SRC_IN
)
nextBtn.text = getString(R.string.next)
nextBtn.background = nextBtnBackground
nextBtn.setTextColor(ContextCompat.getColor(requireContext(), R.color.colorAccent))
nextBtn.setOnClickListener {
clientManagementViewPager?.currentItem = 1
}
clientManagementViewPager?.registerOnPageChangeCallback(object :ViewPager2.OnPageChangeCallback(){
override fun onPageSelected(position: Int) {
super.onPageSelected(position)
when(position){
1 -> nextBtn.hide()
0-> nextBtn.show()
}
}
})
}
}
Child Fragment
class ClientAccountFragment : DaggerFragment(){
private val title by lazy {
getName()
}
private lateinit var nextBtn: Button
private lateinit var progressBar: ProgressBar
#Inject
lateinit var viewModelProviderFactory: ViewModelFactory
private val authViewModel: AuthViewModel by lazy {
ViewModelProvider(this, viewModelProviderFactory).get(AuthViewModel::class.java)
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_client_account, container, false)
}
override fun onResume() {
super.onResume()
(parentFragment as? ClientFragment)?.setItem(2)
nextBtn.setOnClickListener {
Log.i(title, "here2")
(parentFragment as? ClientFragment)?.clientManagementViewPager?.currentItem = 1
}
}
}

I was able to fix this with following lines
val navHostFragment = requireActivity().supportFragmentManager.fragments[0] as NavHostFragment
val parent = navHostFragment.childFragmentManager.primaryNavigationFragment as ClientFragment

Fragments don't communicate via sharedViewModel and LiveData

I want first fragment to observe information via LiveData comming from second fragment. I tried doing the same but only in 1 Fragment and it worked, but as soon as I want to recieve the data in other fragment it stops working (textView has no text). How should I fix this problem?
SharedViewModel:
class SharedViewModel : ViewModel() {
private val selected : MutableLiveData<Person> = MutableLiveData<Person>()
fun select(person: Person){
selected.value = person
}
fun getSelected(): LiveData<Person>{
return selected
}
}
First fragment:
class FirstFragment : Fragment() {
private lateinit var sharedViewModel: SharedViewModel
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
sharedViewModel =
ViewModelProviders.of(this).get(SharedViewModel::class.java)
val root = inflater.inflate(R.layout.fragment_home, container, false)
val textView: TextView = root.findViewById(R.id.text_home)
sharedViewModel.getSelected().observe(viewLifecycleOwner, Observer{
textView.text = it.name
})
return root
}
}
Second Fragment:
class SecondFragment : Fragment() {
private lateinit var sharedViewModel: SharedViewModel
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
sharedViewModel =
ViewModelProviders.of(this).get(SharedViewModel::class.java)
val root = inflater.inflate(R.layout.fragment_dashboard, container, false)
val textView: TextView = root.findViewById(R.id.text_dashboard)
val person = Person("John")
val newPerson = Person("Anton")
val button2: Button = root.findViewById(R.id.button2)
val button: Button = root.findViewById(R.id.button)
button2.setOnClickListener {
sharedViewModel.select(person)
}
button.setOnClickListener {
sharedViewModel.select(newPerson)
}
return root
}
}
Class Person:
class Person (var name: String) {
}

I think you are using https://developer.android.com/reference/android/arch/lifecycle/ViewModelProviders#of(android.support.v4.app.Fragment) but instead you should be using https://developer.android.com/reference/android/arch/lifecycle/ViewModelProviders#of(android.support.v4.app.FragmentActivity). That's how sharing works.