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
}`

recyclerview not visible at run time

I implemented a simple recyclerview using databinding using kotlin language.
In xml, recyclerview seems to be the default,
but when I run it, it doesn't show up as default.
Other buttons and views included in the fragment appear normally when executed, but only the recyclerview is not visible. Which part is wrong?
class WorkFragment : Fragment() {
private var _binding: FragmentWorkBinding? = null
private val binding get() = _binding!!
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
_binding = FragmentWorkBinding.inflate(inflater, container, false)
val view = binding.root
return view
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val data = mutableListOf<WorkList>()
val adapter = WorkAdapter()
adapter.data = data
binding.recycler1.adapter = adapter
binding.recycler1.layoutManager = LinearLayoutManager(requireContext())
}
}
class WorkAdapter : RecyclerView.Adapter<WorkAdapter.ViewHolder>() {
var data = mutableListOf<WorkList>()
class ViewHolder(val binding: RecyclerviewWorkItemBinding) : RecyclerView.ViewHolder(binding.root) {
fun bind(workList: WorkList) {
binding.tvStarttime.text = workList.Starttime
binding.tvAdmin.text = workList.Admin
binding.tvPart.text = workList.Part
binding.tvStoptime.text = workList.Stoptime
binding.tvWorkers.text = workList.Workers.toString()
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): WorkAdapter.ViewHolder {
val binding = RecyclerviewWorkItemBinding.inflate(LayoutInflater.from(parent.context), parent, false)
return ViewHolder(binding)
}
override fun onBindViewHolder(holder: WorkAdapter.ViewHolder, position: Int) {
holder.bind(data[position])
}
override fun getItemCount(): Int {
return data.size
}
// fun replaceList(newList: MutableList<WorkList>) {
// data = newList.toMutableList()
// notifyDataSetChanged()
// }
}
Is there something wrong with my code?
For reference, I just used a fragment, not an activity.

its typically for the RecyclerView to behave like its hidden but actually its not. the reason is you are passing an empty list so the recycler will not be extended or show because there is no items in the list.

How do I filter cards in a RecyclerView through a SearchView (Kotlin)?

I am currently working on a simple journal app where the user can make new entries, which get stored into a room database and displayed through a RecyclerView using cards. I am currently trying to implement a way to filter card entries based on the text within them using a SearchView. However, everything that I've found online seems to be entirely in Java, just filtering a list, etc, so I'm not sure how I would go about doing this. Any help would be massively appreciated!
Here is my code (without imports):
Fragment that displays entries through RecyclerView:
class HomeFragment : BaseFragment() {
private lateinit var homeViewModel: HomeViewModel
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
homeViewModel =
ViewModelProvider(this).get(HomeViewModel::class.java)
val root = inflater.inflate(R.layout.fragment_home, container, false)
return root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
recycler_view.setHasFixedSize(true)
recycler_view.layoutManager = StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL)
launch {
context?.let {
var journal = JournalDatabase.getDatabase(it).JournalDao().allJournal()
recycler_view.adapter = JournalAdapter(journal)
}
}
newEntryButton.setOnClickListener {
Navigation.findNavController(view).navigate(R.id.action_nav_home_to_nav_new_entry)
}
}
}
My adapter:
class JournalAdapter(val arrList: List<Journal>) :
RecyclerView.Adapter<JournalAdapter.JournalViewHolder>() {
class JournalViewHolder(view: View) : RecyclerView.ViewHolder(view) {
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): JournalViewHolder {
return JournalViewHolder(LayoutInflater.from(parent.context).inflate(R.layout.recyclerview_entry, parent, false))
}
override fun onBindViewHolder(holder: JournalViewHolder, position: Int) {
holder.itemView.rvTitle.text = arrList[position].title
holder.itemView.rvText.text = arrList[position].journalText
holder.itemView.rvDateTime.text = arrList[position].dateTime
}
override fun getItemCount(): Int {
return arrList.size
}
}

System services not available to Activities before onCreate(), with Android RecyclerView inside a fragment Kotlin

I'm having trouble with Android RecyclerView in Kotlin inside a fragment who is in Home activity.
Here's my code:
myFragmentLayout:
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/rvChapterList"
android:layout_width="match_parent"
android:layout_height="match_parent" />
myFragmentCode:
val chaptersList: ArrayList<String> = ArrayList()
private lateinit var layoutManager: RecyclerView.LayoutManager
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
return inflater.inflate(R.layout.courses_layout, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
chaptersList.add("Android")
chaptersList.add("Kotlin")
chaptersList.add("RecyclerView")
layoutManager = LinearLayoutManager(context)
rvChapterList.layoutManager = layoutManager
rvChapterList.adapter = ChapterAdapter(Home(), chaptersList)
}
and myChapterAdapter:
class ChapterAdapter(private val context: Home, private val chaptersList: ArrayList<String>) : RecyclerView.Adapter<ChapterAdapter.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
return ViewHolder(LayoutInflater.from(context).inflate(R.layout.list_item, parent, false))
}
override fun getItemCount(): Int {
return chaptersList.size
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.chapterName?.text = chaptersList.get(position)
holder.itemView.setOnClickListener {
Toast.makeText(context, chaptersList.get(position), Toast.LENGTH_LONG).show()
}
}
class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
val chapterName = view.tvChapterName
}
}
It got this code from this tutorial, it's working inside an activity but not iside a fragment.

rvChapterList.adapter = ChapterAdapter(Home(), chaptersList)
Never create an Activity or other type of Context yourself. You always obtain them from the framework.
Replace that with:
rvChapterList.adapter = ChapterAdapter(requireActivity(), chaptersList)
and change the context property in ChapterAdapter to be a Context or Activity, not Home.

Listview adapter in a fragment giving null pointer exception

I made a listview in a fragment
There is a null pointer exception for the adapter of the list view
But the Arraylist and the adapter are not null.
Error: lvElevator cannot be null
The error is for the below line
lvElevator.adapter = EAdapter
Fragment Class
var EList=ArrayList<E1List>()
class EDetails: Fragment() {
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
EList.add(E1List(1))
EList.add(E1List(2))
var EAdapter = EleAdapter(EList)
lvElevator.adapter = EAdapter
return inflater.inflate(R.layout.fragment_elevators, container, false)
}
inner class EleAdapter : BaseAdapter {
var EListAdapter = ArrayList<E1List>()
constructor(EListAdapter: ArrayList<E1List>) : super() {
this.EListAdapter = EListAdapter
}
override fun getView(position: Int, convertView: View?, parent: ViewGroup?): View {
var myView = layoutInflater.inflate(R.layout.elevator_ticket, null)
var myEle = EListAdapter[position]
myView.tvEnum.text = myEle.elevatornum.toString()
return myView
}
override fun getItem(position: Int): Any {
return EListAdapter[position]
}
override fun getItemId(position: Int): Long {
return position.toLong()
}
override fun getCount(): Int {
return EListAdapter.size
}
}
}

You are trying to define lvElevator before fragment inflate the xml layout file.
There is two way to fix it.
1) Use onViewCreated() method instead to load data into views. And use onCreateView method to just inflate the view only.
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
EList.add(E1List(1))
EList.add(E1List(2))
var EAdapter = EleAdapter(EList)
lvElevator.adapter = EAdapter
}
2) Modify onCreateView() method like below.
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
// Define views manually..
val view = inflater.inflate(R.layout.fragment_elevators, container, false)
val lvElevator = view.findViewById<ListView>(R.id.lvElevator)
EList.add(E1List(1))
EList.add(E1List(2))
var EAdapter = EleAdapter(EList)
lvElevator.adapter = EAdapter
return view
}
As an experienced developer, I would recommended to use the first way as that method will only come in scope after layout completely inflated.