Develop Reference

Android: How to reference to an outside View, in RecyclerView

Hi I have an simple app with Bottom Navigation Activity. In Home Fragment I have a Button called Fruits. It opens a PopupWindow. In the popup is a RecyclerView with 4 Buttons(fruits names).
I want, when I press on a Button in the PopupWindow, to change the name of Button(called Fruits) form home_fragment, in whatever fruit was chosen.
HomeFragment:
class HomeFragment : Fragment() {
private var _binding: FragmentHomeBinding? = null
private val binding get() = _binding!!
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
_binding = FragmentHomeBinding.inflate(inflater, container, false)
val root: View = binding.root
return root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
binding.Fruits.setOnClickListener {
show_popup(requireContext(), view, R.layout.fruits_popup)
}
}
override fun onDestroyView() {
super.onDestroyView()
_binding = null
}
fun show_popup(c: Context, v: View, l: Int){
val popup_window = PopupWindow(c)
val inflater = layoutInflater.inflate(l, null)
val recyclerView: RecyclerView = inflater.findViewById(R.id.recycler_view)
recyclerView.layoutManager = LinearLayoutManager(context)
recyclerView.adapter = FruitsAdapter()
popup_window.contentView = inflater
popup_window.isFocusable = true
popup_window.isOutsideTouchable = true
popup_window.showAtLocation(v, Gravity.CENTER, 0, 0)
}
}
FruitsAdapter:
class FruitsAdapter : RecyclerView.Adapter<FruitsAdapter.FruitsViewHolder>() {
private val list = listOf<String>("Banana", "Orange", "Apple", "Watermelon")
class FruitsViewHolder(val view: View): RecyclerView.ViewHolder(view) {
val button = view.findViewById<Button>(R.id.fruit)
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): FruitsViewHolder {
val layout = LayoutInflater.from(parent.context).inflate(R.layout.fruit, parent, false)
return FruitsViewHolder(layout)
}
override fun onBindViewHolder(holder: FruitsViewHolder, position: Int) {
val item = list.get(position)
holder.button.text = item.toString()
}
override fun getItemCount(): Int {
return list.size
}
}
fragment_gome.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ui.home.HomeFragment">
<Button
android:id="#+id/Fruits"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Fruits"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.254" />
</androidx.constraintlayout.widget.ConstraintLayout>
fruits_popup.xml:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<androidx.recyclerview.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/recycler_view"/>
</FrameLayout>
fruit.xml
<?xml version="1.0" encoding="utf-8"?>
<Button xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/fruit"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="4dp"
android:padding="8dp" />

Try to google with keyword 'callback' bro

creating bottom sheet dialog with ConstraintLayout

I am trying to create modal bottom sheet dialog to show a list of items which will be scrollable.
dialog_bottom_example.xml:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/white"
xmlns:app="http://schemas.android.com/apk/res-auto">
<LinearLayout
android:id="#+id/container"
android:layout_width="0dp"
android:layout_height="0dp"
android:orientation="vertical"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
Items in LinearLayout is getting added dynamically based on list size as below:
ExampleDialogBottom:
class ExampleDialogBottom: BottomSheetDialogFragment() {
private lateinit var binding: DialogExampleBinding
private var skusItems = mutableListOf<SkuItem>();
companion object {
internal const val TAG = "ExampleDialogBottom"
#JvmStatic
fun newInstance(nonEligibleErxItem: NonEligibleErxItem) = NonEligibleBottomDialog
}
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
binding = DialogExampleBinding.inflate(inflater, container, false)
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
configureSkuItems()
}
private fun configureSkuItems() {
if (!skuItems.isNullOrEmpty()) {
val inflater = LayoutInflater.from(context)
for (sku in skuItems) {
val skuItemView = SingleSkuItemViewBinding.inflate(inflater, null, false)
skuItemView.skuImage.setImageWithVisibility(sku.imageUrl)
skuItemView.skuTitle.setTextWithVisibility(sku.name)
binding.container.addView(skuItemView.root)
}
binding.container.visibility = View.VISIBLE
} else {
binding.container.visibility = View.GONE
}
}
ExmpaleActivity:
button.setOnClickListener {
ExampleDialogBottom.newInstance().show(getSupportFragmentManager(),
ExampleDialogBottom.TAG);
}
However, when I click on button, a transparent dialog shows up, no content is showing.
When I removed match-contraint and changed it match-parent or wrap-content, it's working as expected.
It would be great if someone could help? Thanks in advance.

databinding on custom view causes type mismatch

I have a custom view (LoadingButton) and when linking it to a variable in my fragment via databinding, it causes the following error: Type mismatch: inferred type is View but LoadingButton was expected
But when i use findViewById it works perfectly fine. How can I use databinding in this case?
Apparently, this question needs more text as there is an error message in stackoverflow which says "It looks like your post ist mostly code; please add some more details", so I guess have to write some more details:
code:
[FRAGMENT] LoginFragment.kt
class LoginFragment : Fragment() {
private lateinit var binding: FragmentLoginBinding
private lateinit var login: LoadingButton
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View {
binding = FragmentLoginBinding.inflate(inflater, container, false)
binding.mainViewModel = mainViewModel
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
initUi()
}
private fun initUi() {
login = binding.buttonLoginLogin // causes error
// login = requireActivity().findViewById(R.id.button_login_login) // doesn't cause error
}
[LAYOUT XML] fragment_login.xml
<?xml version="1.0" encoding="utf-8"?>
<layout>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.myapp.LoadingButton
android:id="#+id/button_login_login"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
[CUSTOM VIEW XML] view_loading_button.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:clipChildren="false">
<ProgressBar
android:id="#+id/progressBar"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:layout_margin="4dp"
app:layout_constraintTop_toTopOf="#id/button"
app:layout_constraintStart_toStartOf="#id/button"
app:layout_constraintBottom_toBottomOf="#id/button"
app:layout_constraintEnd_toEndOf="#id/button"
android:elevation="4dp"/>
<androidx.appcompat.widget.AppCompatButton
android:id="#+id/button"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_centerInParent="true"
android:layout_margin="4dp"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>
[CUSTOM VIEW CLASS] LoadingButton.kt
class LoadingButton #JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0
) :
ConstraintLayout(context, attrs, defStyleAttr) {
private val button: Button
private val progressBar: ProgressBar
private var loading: Boolean = false
private var buttonText: String = ""
private var textColor: Int
init {
inflate(context, R.layout.view_loading_button, this)
button = findViewById(R.id.button)
progressBar = findViewById(R.id.progressBar)
context.theme.obtainStyledAttributes(attrs, R.styleable.LoadingButton, 0, 0).apply {
try {
loading = getBoolean(R.styleable.LoadingButton_loading, false)
buttonText = getString(R.styleable.LoadingButton_text).toString()
textColor = getInt(R.styleable.LoadingButton_textColor, 0)
button.setTextColor(textColor)
button.text = buttonText
button.background = getDrawable(R.styleable.LoadingButton_buttonBackground)
setLoading(loading)
} finally {
recycle()
}
}
}
fun setLoading(isLoading: Boolean) {
loading = isLoading
if (loading) {
this.isClickable = false
button.isClickable = false
buttonText = button.text.toString()
button.text = ""
progressBar.visibility = View.VISIBLE
} else {
this.isClickable = true
button.isClickable = true
button.text = buttonText
progressBar.visibility = View.GONE
}
invalidate()
requestLayout()
}
}

It seems like this is some kind of bug as the code compiles on other user's IDE.
A workaround that works for me is by casting it explicitely (despite the IDE protesting):
login = binding.buttonLoginLogin as LoadingButton

Trouble with Recyclerview. recyclerview.xml must no be null

i have the xml with recyclerview, id = list_chat
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ui.chats.ChatsFragment">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/list_chat"
android:layout_width="match_parent"
android:layout_height="match_parent">
</androidx.recyclerview.widget.RecyclerView>
</androidx.constraintlayout.widget.ConstraintLayout>
my Fragment where will be recyclerview with function uploadList which put data in my array for recyclerView
class ChatsFragment : Fragment() {
var list: MutableList<Chat> = ArrayList()
lateinit var adapter: ChatListAdapter
lateinit var manager: RecyclerView.LayoutManager
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
uploadList()
Log.e("TAG", list.toString())
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val view: View = inflater.inflate(R.layout.fragment_chats, container, false)
uploadList()
manager = LinearLayoutManager(activity)
list_chat.layoutManager = manager
adapter = ChatListAdapter(list)
list_chat.adapter = adapter
return view
}
private fun uploadList(){
list.add(Chat("11111", "11111"))
list.add(Chat("11222221", "133311"))
list.add(Chat("1122221", "114444411"))
list.add(Chat("112222211", "5555555"))
}
}
xml with item for list. ImageView is no matter for now. Need only two textView
<?xml version="1.0" encoding="utf-8"?>
<layout
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
xmlns:android="http://schemas.android.com/apk/res/android">
<LinearLayout
android:id="#+id/item_list"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal">
<de.hdodenhof.circleimageview.CircleImageView
android:id="#+id/chatImage"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#mipmap/ic_launcher"/>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
android:layout_marginStart="5sp">
<TextView
android:id="#+id/nameChat"
android:text="2222222222222"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<TextView
android:id="#+id/infoChat"
android:text="11111111"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
</LinearLayout>
</LinearLayout>
</layout>
and my custom Adapter
class ChatListAdapter(private val myDataset: MutableList<Chat>) :RecyclerView.Adapter<ChatListAdapter.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val layoutInflater = LayoutInflater.from(parent.context)
.inflate(R.layout.item_list, parent, false)
return ViewHolder(layoutInflater)
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.bind(myDataset[position])
}
override fun getItemCount() = myDataset.size
class ViewHolder(v: View) : RecyclerView.ViewHolder(v){
private val nameChat: TextView = itemView.findViewById(R.id.nameChat)
private val infoChat: TextView = itemView.findViewById(R.id.infoChat)
fun bind(chat: Chat){
nameChat.text = chat.name
infoChat.text = chat.info
}
}
}
and i catch java.lang.IllegalStateException: list_chat must not be null here list_chat.layoutManager = manager
help me with it, i have list_chat only in fragment_chats, so it is right recyclerview.
Because help me pls, I dont know what is the problem

Initialize layout manager and adapter in onViewCreated() Method
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
uploadList()
manager = LinearLayoutManager(activity)
list_chat.layoutManager = manager
adapter = ChatListAdapter(list)
list_chat.adapter = adapter
})

Are you using kotlinx.android.synthetic to find your views? If so, these are not valid until after onCreateView() returns, and so you cannot use them within onCreateView().
Move your code to onViewCreated(), or switch to manually calling view.findViewById() from inside onCreateView().

Approach 1 :
Create a recyclerview object :
val rv = view.findViewById(your rv id)
and assign the layout manager and adapter to it.
Approach 2 :
In your layout file, in recyclerview add this line :
<androidx.recyclerview.widget.RecyclerView
<!-- your default lines -->
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
/>
and assign the adapter in onViewCreated method.

Android recyclerView problem - multi-layer scrolling content?

I am brand new in Android/kotlin development. I created my very first app with a recyclerView to display the folders and files of the phone. I put the recyclerView into a segment, created my data structure and adapter. Assembled together. It works - or seems to work. But the problem is that when I try to scroll the list, the initial state remains "ther" and the list content starts to scroll. Like it was two different layers. I have no clue where to find the problem. Never heard about such a bug like this. Please give me advice, some keywords where to dig and find the solution. Thanks!
class BrowseFileFragment : Fragment() {
private lateinit var attachedCtx : Context
override fun onAttach(context: Context) {
super.onAttach(context)
this.attachedCtx = context
}
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,savedInstanceState: Bundle?): View?
{
var view : View = inflater.inflate(R.layout.fragment_browse_file, container, false)
val modelFactory = FileBrowseModelFactory()
val data = modelFactory.create()
bindModelToView(data, view)
return view
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
}
private fun bindModelToView(data: BrowseSettings, view: View)
{
var adapter = MyFileAdapter(data.FoldersAndFiles, this.attachedCtx)
var recyclerView = view.findViewById<RecyclerView>(R.id.fileItemView)
var linearLayoutManager = LinearLayoutManager(this.attachedCtx)
recyclerView.layoutManager = linearLayoutManager
recyclerView.adapter = adapter
var folderLabel = view.findViewById<TextView>(R.id.folderName)
folderLabel.text = data.CurrentFolder
}
}
The segment layout
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".BrowseFileFragment">
<TextView
android:id="#+id/folderName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="5dp"
android:text="#string/hello_first_fragment"
android:textAlignment="viewStart"
android:textAppearance="#style/TextAppearance.AppCompat.Display1"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/fileItemView"
android:layout_width="match_parent"
app:layout_constrainedHeight="true"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="#+id/folderName"
app:layout_constraintStart_toStartOf="#+id/folderName"
app:layout_constraintTop_toBottomOf="#+id/folderName" />
</androidx.constraintlayout.widget.ConstraintLayout>
The list line layout
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="60dp">
<TextView
android:background="#color/cardview_shadow_start_color"
android:id="#+id/itemName"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintBottom_toTopOf="parent"
android:padding="5dp"
android:textSize="30dp"
android:textStyle="bold" />
</androidx.constraintlayout.widget.ConstraintLayout>
And finally my adapter:
class MyFileAdapter(private val items: List<FileItem>, private val context: Context)
: RecyclerView.Adapter<MyFileAdapter.MyViewHolder>()
{
class MyViewHolder (itemView: View) :RecyclerView.ViewHolder(itemView), View.OnClickListener {
init {
itemView.setOnClickListener(this)
}
fun bindItem(f: FileItem) {
var name: TextView = itemView.findViewById(R.id.itemName) as TextView
name.text = f.Name
}
}
override fun getItemCount() = items.size
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
val view = LayoutInflater
.from(context)
.inflate(R.layout.recyclerview_filteitem_row, parent, false)
return MyViewHolder(view)
}
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
var item = items\[position\]
holder!!.bindItem( item )
}
}

It found out that as the whole list view is saved as a segment, this segment loads "automatically" and was loaded programatically also, and the two "loads" causes this thing. :( Thanks for your time guys.