Develop Reference

RecyclerView shows a list of copies of activity screen instead of data from database table

I am simply trying to setup the ClickListener for changing the user name. Google's tutorials emphasize fragments, which I will do later. Based on what I've seen in other examples and the Android documentation, I thought I had the View Binding set up properly. I don't have enough information to understand why I see a list of copies of the activity screen inside the RecyclerView.
UserListAdapter.kt
package com.neillbarrett.debitsandcredits
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.EditText
import android.widget.TextView
import android.widget.Toast
import androidx.recyclerview.widget.DiffUtil
import androidx.recyclerview.widget.ListAdapter
import androidx.recyclerview.widget.RecyclerView
import com.neillbarrett.debitsandcredits.database.UsersTable
import com.neillbarrett.debitsandcredits.databinding.ActivityManageUsersBinding
val inAdapter: String = "In UserListAdapter "
class UserListAdapter(private val userSelect: (UsersTable?) -> Unit) :
ListAdapter<UsersTable, UserListAdapter.UserViewHolder>(UsersComparator()) {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): UserListAdapter.UserViewHolder {
Log.w(inAdapter,"OnCreateViewHolder started")
val view = LayoutInflater.from(parent.context)
.inflate(R.layout.activity_manage_users, parent, false)
return UserViewHolder.create(parent)
}
class UserViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
fun bind(usersTable: UsersTable?, userSelect: (UsersTable?) -> Unit) {
Log.w(inAdapter,"UserViewHolder started")
itemView.setOnClickListener { View.OnClickListener {
/* if (View.) { }*/
val nameSelected = userSelect(usersTable)
//userSelect(usersTable)
//need to assign the result of the clicklistener to the editText
//binding.etEditName.setText(R.layout.activity_list_of_users.toString())
}}
}
companion object {
fun create(parent: ViewGroup) : UserViewHolder {
Log.w(inAdapter,"Companion object 'Create' function started")
val view: View = LayoutInflater.from(parent.context)
.inflate(R.layout.activity_manage_users, parent, false)
return UserViewHolder(view)
}
}
}
override fun onBindViewHolder(holder: UserViewHolder, position: Int) {
Log.w(inAdapter,"OnBindViewHolder started")
val current = getItem(position)
holder.bind(current, userSelect)
}
class UsersComparator : DiffUtil.ItemCallback<UsersTable>() {
override fun areItemsTheSame(oldItem: UsersTable, newItem: UsersTable): Boolean {
Log.w(inAdapter,"areItemsTheSame function started")
return oldItem == newItem
}
override fun areContentsTheSame(oldItem: UsersTable, newItem: UsersTable): Boolean {
Log.w(inAdapter,"areContentsTheSame function started")
return oldItem.userName == newItem.userName
}
}
}
ManageUsers.kt
package com.neillbarrett.debitsandcredits
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.text.TextUtils
import android.util.Log
import android.widget.Button
import android.widget.EditText
import android.widget.Toast
import androidx.activity.viewModels
import androidx.lifecycle.Observer
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.neillbarrett.debitsandcredits.database.CreditsAndDebitsApp
import com.neillbarrett.debitsandcredits.database.UsersTable
import com.neillbarrett.debitsandcredits.databinding.ActivityManageUsersBinding
class ManageUsers : AppCompatActivity() {
lateinit var binding: ActivityManageUsersBinding
lateinit var recyclerView: RecyclerView
lateinit var editTextAddUser: EditText
lateinit var editTextChangeUser: EditText
lateinit var newUser: String
var userSelect: ((UsersTable?) -> Unit) = {}
var position: Long = 0
val inWhichActivity: String = "In ManageUsers"
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityManageUsersBinding.inflate(layoutInflater)
val view = binding.root
setContentView(view)
//setContentView(R.layout.activity_manage_users)
Log.w(inWhichActivity, "Setting up userViewModel & repository")
val userViewModel: UserViewModel by viewModels {
UserViewModelFactory((application as CreditsAndDebitsApp).repository)
}
recyclerView = findViewById(R.id.rec_view_userList)
editTextAddUser = findViewById(R.id.et_AddUser)
editTextChangeUser = findViewById(R.id.et_Edit_Name)
val adapter = UserListAdapter(userSelect)
binding.recViewUserList.adapter = adapter
recyclerView.adapter = adapter
recyclerView.layoutManager = LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false)
userViewModel.allUsers.observe(this, Observer() {user ->
Log.w(inWhichActivity,"Starting Observer")
user?.let { adapter.submitList(it) }
Log.w(inWhichActivity, "Started Observer")
})
val btnAddUser = findViewById<Button>(R.id.btn_AddUser)
btnAddUser.setOnClickListener {
Log.w(inWhichActivity,"Started btnAddUser.setOnClickListener")
if (TextUtils.isEmpty(editTextAddUser.text)) {
Toast.makeText(this, "User name cannot be empty", Toast.LENGTH_SHORT).show()
} else {
newUser = editTextAddUser.text.toString()
// Log.w("Add user button", "Username put into newUser")
userViewModel.insertUser(UsersTable(0, newUser))
// Toast.makeText(this, "Username added to table", Toast.LENGTH_SHORT).show()
// Log.w("Add user button", "Username added to table")
}
}
val btnChangeUser = findViewById<Button>(R.id.btn_ChangeUserName)
btnChangeUser.setOnClickListener {
Log.w(inWhichActivity,"Started btnChangeUser.setOnClickListener")
Toast.makeText(this, "Selected position is ${recyclerView.getChildAdapterPosition(it)}", Toast.LENGTH_SHORT).show()
/* if (recyclerView.getChildAdapterPosition(it) == -1) {
Toast.makeText(this, "Select a name.", Toast.LENGTH_SHORT).show()
} else {
if (editTextChangeUser.text.toString() == recyclerView.adapter.toString()) {
Toast.makeText(this, "Name has not been changed.", Toast.LENGTH_SHORT).show()
} else {
Toast.makeText(this, "Name would have been changed.", Toast.LENGTH_SHORT).show()
val rvItemRecId: Long
rvItemRecId = adapter.getItemId(position.toInt())
userViewModel.updateUser(UsersTable(rvItemRecId.toInt(), adapter.toString()))
}
}*/
}
}
}
UserViewModel.kt
package com.neillbarrett.debitsandcredits
import android.util.Log
import androidx.lifecycle.*
import com.neillbarrett.debitsandcredits.database.UsersTable
import kotlinx.coroutines.launch
import java.lang.IllegalArgumentException
val inViewModel: String = "In UserViewModel "
class UserViewModel(private val repository: UserRepository) : ViewModel() {
// Using LiveData and caching what allWords returns has several benefits:
// - We can put an observer on the data (instead of polling for changes) and only update the
// the UI when the data actually changes.
// - Repository is completely separated from the UI through the ViewModel.
val allUsers: LiveData<List<UsersTable>> = repository.allUsers.asLiveData()
/**
* Launching a new coroutine to insert the data in a non-blocking way
*/
fun insertUser(user: UsersTable) = viewModelScope.launch {
repository.insertUser(user)
Log.w(inViewModel,"insertUser called")
//repository.insertUser(usersTable = List<UsersTable>())
//repository.insertUser(UsersTable(0, userName = user.userName))
}
fun updateUser(user: UsersTable) = viewModelScope.launch {
repository.updateUser(user)
Log.w(inViewModel, "updateUser called")
}
fun deleteUser(user: UsersTable) = viewModelScope.launch {
repository.deleteUser(user)
Log.w(inViewModel, "deteUser called")
}
}
class UserViewModelFactory(private val repository: UserRepository) : ViewModelProvider.Factory{
override fun <T : ViewModel> create(modelClass: Class<T>): T {
Log.w(inViewModel,"UserViewModelFactory called")
if (modelClass.isAssignableFrom(UserViewModel::class.java)) {
#Suppress("UNCHECKED_CAST")
return UserViewModel(repository) as T
}
throw IllegalArgumentException("Unknown ViewModel class")
}
}

How to call a method in adapter from a fragment in kotlin?

I have been trying to call a function from fragment to adapter, but I can't approach it right.
I want to invisible the button present in the fragment from adapter.
**My Adapter Code:**
package com.littleboo.brandlogo.Adapters
import android.R
import android.content.Context
import android.content.Intent
import android.graphics.Color
import android.graphics.drawable.ColorDrawable
import android.net.Uri
import android.os.Build
import android.os.VibrationEffect
import android.os.Vibrator
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.view.animation.Animation
import android.view.animation.AnimationUtils
import android.widget.Button
import android.widget.TextView
import android.widget.Toast
import androidx.appcompat.app.AlertDialog
import androidx.core.content.ContextCompat.getSystemService
import androidx.recyclerview.widget.RecyclerView
import com.littleboo.brandlogo.Fragments.QuizFragment
import com.littleboo.brandlogo.MainActivity
import com.littleboo.brandlogo.Models.Question
import com.littleboo.brandlogo.databinding.ActivityMainBinding.inflate
import com.littleboo.brandlogo.databinding.FragmentQuizBinding
import kotlinx.coroutines.NonDisposableHandle.parent
class QuestionAdap(val context: Context, val question: Question) :
RecyclerView.Adapter<QuestionAdap.OptionViewHolder>() {
var index = 1
var score = 0
val animShake: Animation = AnimationUtils.loadAnimation(context, com.littleboo.brandlogo.R.anim.shake)
private var options: List<String> = listOf(question.option1, question.option2, question.option3, question.option4)
inner class OptionViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView){
var optionView = itemView.findViewById<TextView>(com.littleboo.brandlogo.R.id.quiz_option)
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): OptionViewHolder {
val view = LayoutInflater.from(context).inflate(com.littleboo.brandlogo.R.layout.quizoptions, parent, false)
return OptionViewHolder(view)
}
override fun onBindViewHolder(holder: OptionViewHolder, position: Int) {
holder.optionView.text = options[position]
holder.itemView.setOnClickListener {
question.userAnswer = options[position]
notifyDataSetChanged()
}
if(question.userAnswer == options[position] && question.userAnswer == question.answer){
holder.itemView.setBackgroundResource(com.littleboo.brandlogo.R.drawable.option_item_selected_bg)
score += 10
Toast.makeText(context,"Score is $score", Toast.LENGTH_SHORT).show()
}
else if(question.userAnswer == options[position] && question.userAnswer != question.answer){
holder.itemView.setBackgroundResource(com.littleboo.brandlogo.R.drawable.wrong_option_item_selected_bg)
holder.itemView.startAnimation(animShake)
}
else{
holder.itemView.setBackgroundResource(com.littleboo.brandlogo.R.drawable.non_option_item_selected_bg)
}
}
override fun getItemCount(): Int {
return options.size
}
}
My Quiz Fragment Code:
package com.littleboo.brandlogo.Fragments
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Button
import androidx.fragment.app.Fragment
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import androidx.swiperefreshlayout.widget.CircularProgressDrawable
import com.bumptech.glide.Glide
import com.google.firebase.firestore.FirebaseFirestore
import com.littleboo.brandlogo.Adapters.QuestionAdap
import com.littleboo.brandlogo.Models.Question
import com.littleboo.brandlogo.Models.quizmodel
import com.littleboo.brandlogo.R
import com.littleboo.brandlogo.databinding.FragmentQuizBinding
class QuizFragment : Fragment(){
lateinit var binding: FragmentQuizBinding
var quizzes: MutableList<quizmodel>? = null
private var questions = mutableMapOf<String, Question>()
private lateinit var mArraylist: ArrayList<Question>
var index = 1
private lateinit var mfirestore: FirebaseFirestore
private lateinit var mrecycler: RecyclerView
lateinit var myadapter: QuestionAdap
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
binding = FragmentQuizBinding.inflate(layoutInflater)
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
mrecycler = binding.optionList
mrecycler.layoutManager
myadapter = QuestionAdap(requireContext(),Question())
mArraylist = arrayListOf()
questions.map { it.key to it.value }.shuffled().toMap()
setUpFirestore()
setUpEventListener()
}
override fun onDestroy() {
super.onDestroy()
mfirestore.terminate()
// finish()
}
private fun setUpEventListener() {
binding.nextbtn.setOnClickListener {
index++
bindViews()
}
// binding.btnSubmit.setOnClickListener {
// Log.d("FINALQUIZ", questions.toString())
// val intent = Intent(this, ResultActivity::class.java)
// val json = Gson().toJson(quizzes!![0])
// intent.putExtra("QUIZ", json)
// startActivity(intent)
// finish()
// }
}
private fun setUpFirestore() {
mfirestore = FirebaseFirestore.getInstance()
val quizTitle = activity?.intent?.getStringExtra("title")
if (quizTitle != null) {
mfirestore.collection("Quizes").whereEqualTo("title", quizTitle)
.get()
.addOnSuccessListener {
if (it != null && !it.isEmpty) {
quizzes = it.toObjects(quizmodel::class.java)
questions = quizzes!![0].questions
shuffle()
bindViews()
}
}
}
}
private fun bindViews() {
// btnPrevious.visibility = View.GONE
// binding.btnSubmit.visibility = View.GONE
// binding.btnNext.visibility = View.GONE
// if (index == 1) { //first question
// binding.btnNext.visibility = View.VISIBLE
// } else if (index == questions!!.size) { // last question
// binding.btnSubmit.visibility = View.VISIBLE
//// btnPrevious.visibility = View.VISIBLE
// } else { // Middle
//// btnPrevious.visibility = View.VISIBLE
// binding.btnNext.visibility = View.VISIBLE
// }
val circularProgressDrawable = CircularProgressDrawable(requireContext())
circularProgressDrawable.strokeWidth = 8f
// circularProgressDrawable.colorFilter = ("#ac5fe1")
circularProgressDrawable.centerRadius = 30f
circularProgressDrawable.start()
val question = questions!!["question$index"]
question?.let {
Glide.with(this).load(it.imagequiz).placeholder(circularProgressDrawable).into(binding.imagequiz)
val optionAdapter = QuestionAdap(requireContext(), it)
mrecycler.layoutManager = LinearLayoutManager(requireContext())
mrecycler.adapter = optionAdapter
mrecycler.setHasFixedSize(true)
}
}
private fun shuffle() {
val keys = questions.keys.toMutableList().shuffled()
val values = questions.values.toMutableList().shuffled()
keys.forEachIndexed { index, key ->
questions[key] = values[index]
}
}
}
I tried calling fragment in adapter like:
QuizFragment().binding.btnxt.visibility = View.Visible
in BindViewHolder function.
Thank You

You can use kotlin lambda function to achieve it. Like this
class QuestionAdap(val context: Context, val question: Question, var onItemClicked: ((boolean) -> Unit))
call onItemClicked in your adapter where you want it
and in fragment
myadapter = QuestionAdap(requireContext(),Question()) { boolean ->
if (boolean) {
//hide/show
} else {
//hide/show
}
}

You can use the Callback functions of kotlin in your fragment, which will be passed into your adapter. So whenever you invoke that callback from your adapter, it will be triggered in your fragment.
Step 1: Create a method like the one below in your fragment.
private fun showHideButtonFromAdapter (
isButtonVisible: Boolean
) {
// set your button visibility according to isButtonVisible value.
}
Step 2: pass a method from your fragment to adapter as argument
val adapter = YourAdapter(::showHideButtonFromAdapter)
// set above adapter in your recycler view.
Step 3: In your adapter invoke that callback function like the one below.
class ColorPickerAdapter constructor(
private val onItemClicked: (Boolean) -> Unit
) : RecyclerView.Adapter<YourAdapter.ViewHolder>() {
// your other adapter methods here
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
onItemClicked.invoke(pass true or false as per your requirement)
// above invocation will trigger an event in the fragment.
}
}

In your adapter there need to be instance of your fragment, so change it like:
class QuestionAdap(val context: Context, val question: Question, fragment: Fragment) :
RecyclerView.Adapter<QuestionAdap.OptionViewHolder>() {
Then you can call your fragment by simply writing fragment in your adapter like:
override fun onBindViewHolder(holder: OptionViewHolder, position: Int) {
holder.optionView.text = options[position]
holder.itemView.setOnClickListener {
question.userAnswer = options[position]
notifyDataSetChanged()
}
//Example
fragment.shuffle()
And you need to send this fragment instance when you create it's adapter, so in your fragment use this:
myadapter = QuestionAdap(requireContext(),Question(), this)

Adding multiple items in cart for multiple types of products clicked. Ecom app Android Kotlin

As of now I have fetched some product data from api and showing it on homescreen. Now I have detailed screen for each product and from detailed screen user can add that product with whatever quantity into cart screen. Now I want to add multiple products with any number of quantity into cart screen and each product is shown on different cards into cart screen.
How can I achieve that? Currently I am able to do it for one product but quantity value is same for all types of products on click.
This is my ProductDetail fragment for each product from where I am adding items and it's quantity to the cart.
package com.example.ecomapp.view
import android.app.Application
import android.os.Bundle
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Toast
import androidx.activity.viewModels
import androidx.appcompat.app.AppCompatActivity
import androidx.core.os.bundleOf
import androidx.fragment.app.*
import com.example.ecomapp.CartFragment
import com.example.ecomapp.R
import com.example.ecomapp.databinding.FragmentProductDetailBinding
import com.example.ecomapp.viewmodel.MainViewModel
import com.google.android.material.bottomnavigation.BottomNavigationView
import java.util.*
import kotlin.collections.ArrayList
class ProductDetailFragment : Fragment() {
lateinit var binding: FragmentProductDetailBinding
//var quantityValue = 0
private val viewmodel:MainViewModel by activityViewModels()
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
/// return inflater.inflate(R.layout.fragment_product_detail, container, false)
binding = FragmentProductDetailBinding.inflate(inflater,container,false)
// Log.d("PriceAmount", binding.priceAmount.text.toString())
Log.d("Price", binding.price.toString())
Log.d("Title", binding.titleDetail.toString())
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val navBar:BottomNavigationView = requireActivity().findViewById(R.id.bottomNavigation)
// navBar.visibility = View.GONE
binding.productDetails1 = arguments?.getParcelable("product")
var productDetail = binding.productDetails1
val currency:Currency = Currency.getInstance(Locale.getDefault())
val symbol = currency.symbol
binding.price.text = "$symbol ${productDetail?.price}"
binding.lifecycleOwner = viewLifecycleOwner
viewmodel.idsList.add(productDetail?.id)
val array = viewmodel.idsList
Log.d("List of ids",array.toString())
// var priceAmount = binding.priceAmount.text.toString().toFloat()
// Log.d("PriceAmount", binding.priceAmount.toString())
// Log.d("ProductTitle", binding.productDetails1.title)
binding.addButton.setOnClickListener {
// Log.d("ProductDetail",initialValue.toString())
if (productDetail == null) return#setOnClickListener
viewmodel.quantityValue = viewmodel.quantityValue + 1
// binding.totalPriceText.text = "Total price"
binding.quantityText.text = viewmodel.quantityValue.toString()
// binding.priceAmount.text =
// (productDetail.price * viewmodel.quantityValue).toString()
}
binding.addCartButton.setOnClickListener{
viewmodel.quantityValue = viewmodel.quantityValue + 1
binding.quantityText.text = viewmodel.quantityValue.toString()
Toast.makeText(activity, "Item added to cart", Toast.LENGTH_SHORT).show()
}
// Log.d("ProductDetail",priceAmount.toString())
/* binding.removeButton.setOnClickListener {
if (quantityValue != 0) {
if (productDetail == null) return#setOnClickListener
quantityValue = quantityValue - 1
binding.quantityText.text = quantityValue.toString()
// binding.priceAmount.text = (priceAmount*quantityValue).toString()
binding.priceAmount.text = (productDetail.price * quantityValue).toString()
}
} */
binding.continueButton.setOnClickListener{
val bundle = Bundle()
bundle.putString("quantity_text", String.format("%d",viewmodel.quantityValue))
val cartFragment = CartFragment()
cartFragment.arguments = bundle
val ft = fragmentManager?.beginTransaction()
ft?.replace(R.id.flFragment,cartFragment)
ft?.addToBackStack("")
ft?.commit()
// Create the transaction
// Create the transaction
}
Toast.makeText(activity,"onCreateViewCalled",Toast.LENGTH_SHORT).show()
// binding.productDetails = viewModel.products.value!!.get(0)
// binding.lifecycleOwner = viewLifecycleOwner
}
override fun onResume() {
super.onResume()
(activity as AppCompatActivity?)!!.supportActionBar!!.hide()
binding.quantityText.text = viewmodel.quantityValue.toString()
// binding.priceAmount.text = (binding.productDetails1!!.price!! * viewmodel.quantityValue).toString()
Toast.makeText(activity,"onResumeCalled",Toast.LENGTH_SHORT).show()
}
override fun onStop() {
super.onStop()
// (activity as AppCompatActivity?)!!.supportActionBar!!.show()
Toast.makeText(activity,"onStopCalled",Toast.LENGTH_SHORT).show()
}
override fun onPause() {
super.onPause()
Toast.makeText(activity,"onPauseCalled",Toast.LENGTH_SHORT).show()
}
override fun onDestroyView() {
super.onDestroyView()
Toast.makeText(activity,"onDestroyViewCalled",Toast.LENGTH_SHORT).show()
}
override fun onDestroy() {
super.onDestroy()
Toast.makeText(activity,"onDestroyCalled",Toast.LENGTH_SHORT).show()
}
}
And this is my MainViewModel from where I am getting data of quantity value throughout the fragments.
package com.example.ecomapp.viewmodel
import androidx.lifecycle.LiveData
import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import com.example.ecomapp.data.Repository
import com.example.ecomapp.model.ProductDataModel
import com.example.ecomapp.model.ProductsData
import kotlinx.coroutines.delay
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.asStateFlow
import kotlinx.coroutines.launch
class MainViewModel: ViewModel(){
private val repository = Repository()
private val _products = MutableLiveData<List<ProductDataModel>>()
val products:LiveData<List<ProductDataModel>> = _products
private val _isLoading = MutableStateFlow(true)
val isLoading = _isLoading.asStateFlow()
private var quantity_value = 0
var quantityValue = quantity_value
init {
viewModelScope.launch {
delay(3000)
_isLoading.value = false
}
getProducts()
}
fun addQuantityValue(): Int? {
quantity_value = quantityValue + 1
return quantity_value
}
/* fun productPrice(quantity:Int):Float {
_price.value =
} */
private fun getProducts() {
viewModelScope.launch {
val data = repository.getProducts()
_products.postValue(data)
}
}
}

Not able to setup optionMenu using NavigationUI

I have Fragment and i want to add option menu. I have tried a lot but not found any solution.
Here is my code.
package com.code2hack.milkledger.fragment
import android.app.AlertDialog
import android.os.Bundle
import android.view.*
import androidx.appcompat.view.ActionMode
import androidx.appcompat.widget.Toolbar
import androidx.core.content.ContextCompat
import androidx.fragment.app.activityViewModels
import androidx.fragment.app.viewModels
import androidx.lifecycle.Observer
import androidx.navigation.findNavController
import androidx.navigation.fragment.findNavController
import androidx.navigation.ui.AppBarConfiguration
import androidx.navigation.ui.NavigationUI
import androidx.navigation.ui.setupWithNavController
import androidx.recyclerview.widget.LinearLayoutManager
import com.code2hack.milkledger.BaseActivity
import com.code2hack.milkledger.MainActivityViewModel
import com.code2hack.milkledger.R
import com.code2hack.milkledger.actionmode.ActionModeCallback
import com.code2hack.milkledger.adapter.CustomerAdapter
import com.code2hack.milkledger.dialog.AddUserDialog
import com.code2hack.milkledger.handler.ItemClickListener
import com.code2hack.milkledger.model.Customer
import com.code2hack.milkledger.util.Event
import com.google.android.material.card.MaterialCardView
import com.google.android.material.snackbar.Snackbar
import kotlinx.android.synthetic.main.fragment_customer_list.*
class CustomerListFragment : BaseFragment() {
private val baseActivity: BaseActivity by lazy { activity as BaseActivity };
private var selectMode = false
val selectedCustomers = mutableSetOf<Customer>()
val selectedViews = mutableSetOf<View>()
private lateinit var actionMode: ActionMode
private val list = mutableListOf<Customer>()
private val model: MainActivityViewModel by activityViewModels()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setHasOptionsMenu(true)
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_customer_list, container, false)
}
private val customerAdapter: CustomerAdapter by lazy { CustomerAdapter(list,ClickHandler()) }
override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
inflater.inflate(R.menu.menu_main, menu)
super.onCreateOptionsMenu(menu, inflater)
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
return NavigationUI.onNavDestinationSelected(item,
findNavController())
|| super.onOptionsItemSelected(item)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val navController = findNavController()
val appBarConfiguration = AppBarConfiguration(navController.graph)
view.findViewById<Toolbar>(R.id.toolbar)
.setupWithNavController(navController, appBarConfiguration)
//baseActivity.setSupportActionBar(toolbar)
fab.setOnClickListener {
baseActivity.showDialog(AddUserDialog(null))
}
customer_view.apply {
layoutManager = LinearLayoutManager(activity)
adapter = customerAdapter
}
model.loadCustomers(userInfo().user_name,token())
observe();
}
private fun observe() {
with(model){
customers.observe(viewLifecycleOwner, Observer { items ->
if(items.isEmpty()){
baseActivity.showDialog(AddUserDialog(null))
}
list.clear();
list.addAll(items);
customerAdapter.notifyDataSetChanged();
})
customerSaved.observe(viewLifecycleOwner, Observer {
if(!it.handled){
Snackbar.make(requireView(),getString(R.string.message_customer_create),Snackbar.LENGTH_LONG).show()
list.add(it.getContentIfNotHandled()!!)
customerAdapter.notifyDataSetChanged()
}
})
customerDeleted.observe(viewLifecycleOwner, Observer {
if(!it.handled){
handleDeleteEvent(it, requireView(), customerAdapter)
}
})
}
}
private fun handleDeleteEvent(
it: Event<Boolean>,
view: View,
customerAdapter: CustomerAdapter
) {
it.getContentIfNotHandled()
Snackbar.make(view, getString(R.string.message_customer_delete), Snackbar.LENGTH_LONG).show()
model.loadCustomers(userInfo().user_name, token())
selectMode = false
selectedCustomers.clear()
selectedViews.clear()
actionMode.finish()
list.clear()
customerAdapter.notifyDataSetChanged()
}
private fun deleteCustomers(){
val dialog = AlertDialog.Builder(requireActivity())
.setMessage(R.string.delete_confirm_message)
.setPositiveButton(R.string.delete){ dialogInterface, _ ->
model.deleteCustomer(selectedCustomers, token(), userInfo().user_name)
clearSelectMode()
dialogInterface.cancel()
}.setNegativeButton(R.string.cancel){ dialogInterface, _ ->
clearSelectMode()
dialogInterface.cancel()
}
.create()
dialog.setOnShowListener {
dialog.getButton(AlertDialog.BUTTON_POSITIVE).setTextColor(ContextCompat.getColor(requireContext(),R.color.colorAccent))
dialog.getButton(AlertDialog.BUTTON_NEGATIVE).setTextColor(ContextCompat.getColor(requireContext(),R.color.cancel_text_red))
}
dialog.show();
}
val actionModeCallback = ActionModeCallback({
when(it) {
R.id.action_logout -> {
(baseActivity).logout();
true
}
R.id.delete -> {
deleteCustomers()
true
}
R.id.edit -> {
baseActivity.showDialog(AddUserDialog(selectedCustomers.first()))
true
}
else -> false
}
},{
selectMode = false
selectedCustomers.clear()
selectedViews.forEach{
(it as MaterialCardView).setCardBackgroundColor(ContextCompat.getColor(requireActivity(),android.R.color.white))
}
selectedViews.clear()
},{
it.findItem(R.id.delete).isVisible = selectedCustomers.size > 0
it.findItem(R.id.edit).isVisible = selectedCustomers.size == 1
})
inner class ClickHandler : ItemClickListener<Customer>() {
val TAG = "ClickHandler"
override fun onItemClick(item: Customer, view:View?) {
if(selectMode){
processSelection(item,view)
} else {
val action = CustomerListFragmentDirections.recordFragment(item.id)
action.setCowMilkRate(item.cowMilkRate)
action.setBuffaloMilkRate(item.buffaloMilkRate)
view!!.findNavController().navigate(action)
}
}
override fun onLongClick(item: Customer, view: View?){
selectMode = true
actionMode = baseActivity.startSupportActionMode(actionModeCallback)!!
processSelection(item,view)
}
private fun processSelection(customer: Customer, view: View?){
if(selectedCustomers.indexOf(customer) < 0) {
selectedCustomers.add(customer)
selectedViews.add(view!!)
(view as MaterialCardView).setCardBackgroundColor(ContextCompat.getColor(requireActivity(),R.color.background_light_green))
}
else {
selectedCustomers.remove(customer)
selectedViews.remove(view!!)
(view as MaterialCardView).setCardBackgroundColor(ContextCompat.getColor(requireActivity(),android.R.color.white))
}
if(selectedCustomers.size == 0){
clearSelectMode();
} else {
actionMode.invalidate()
}
}
}
private fun clearSelectMode() {
actionMode.finish()
selectMode = false
selectedCustomers.clear()
selectedViews.clear()
}
}
The method onCreateOptionsMenu is not getting executed.
What i am missing i have no idea. There is no actionbar in my activity. I have put action bar in the fragment_customer_list. Action bar is displayed properly. But not able to add menu to the toolbar

Since you are not calling the setSupportActionBar you should use the Toolbar APIs directly.
Something like:
toolbar.inflateMenu(R.menu.menu_main)
toolbar.setOnMenuItemClickListener {
it.onNavDestinationSelected(navController)
}
NavigationUI.setupWithNavController(
toolbar, navController, appBarConfiguration)

ViewModel updates on screen rotation

I've created a simple project to study Kotlin and Android architecture
https://github.com/AOreshin/shtatus
The screen consists of RecyclerView and three EditTexts.
Corresponding ViewModel is exposing 7 LiveData's:
Three LiveData corresponding to filters
Event to notify the user that no entries are found
Event to notify the user that no entries are present
Status of SwipeRefreshLayout
List of connections to show based on filter input
When user types text in filter ViewModel's LiveData gets notified about the changes and updates the data. I 've read that it's a bad practice to expose MutableLiveData to Activities/Fragments but they have to notify ViewModel about the changes somehow. When no entries are found based on the user's input Toast is shown.
The problem
When the user enters filter values that have no matches, Toast is shown. If the user then rotates the device Toast is shown again and again.
I've read these articles:
https://medium.com/androiddevelopers/livedata-with-snackbar-navigation-and-other-events-the-singleliveevent-case-ac2622673150
https://proandroiddev.com/livedata-with-single-events-2395dea972a8
But I don't understand how I can apply these to my use case. I think the problem in how I perform the updates
private val connections = connectionRepository.allConnections()
private val mediatorConnection = MediatorLiveData<List<Connection>>().also {
it.value = connections.value
}
private val refreshLiveData = MutableLiveData(RefreshStatus.READY)
private val noMatchesEvent = SingleLiveEvent<Void>()
private val emptyTableEvent = SingleLiveEvent<Void>()
val nameLiveData = MutableLiveData<String>()
val urlLiveData = MutableLiveData<String>()
val actualStatusLiveData = MutableLiveData<String>()
init {
with(mediatorConnection) {
addSource(connections) { update() }
addSource(nameLiveData) { update() }
addSource(urlLiveData) { update() }
addSource(actualStatusLiveData) { update() }
}
}
fun getRefreshLiveData(): LiveData<RefreshStatus> = refreshLiveData
fun getNoMatchesEvent(): LiveData<Void> = noMatchesEvent
fun getEmptyTableEvent(): LiveData<Void> = emptyTableEvent
fun getConnections(): LiveData<List<Connection>> = mediatorConnection
private fun update() {
if (connections.value.isNullOrEmpty()) {
emptyTableEvent.call()
} else {
mediatorConnection.value = connections.value?.filter { connection -> getPredicate().test(connection) }
if (mediatorConnection.value.isNullOrEmpty()) {
noMatchesEvent.call()
}
}
}
update() gets triggered on screen rotation because of new subscription to mediatorConnection and MediatorLiveData.onActive() is called. And it's intented behavior
Android live data - observe always fires after config change
Code for showing toast
package com.github.aoreshin.shtatus.fragments
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.EditText
import android.widget.Toast
import androidx.core.widget.addTextChangedListener
import androidx.fragment.app.Fragment
import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModelProvider
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import androidx.swiperefreshlayout.widget.SwipeRefreshLayout
import com.github.aoreshin.shtatus.R
import com.github.aoreshin.shtatus.ShatusApplication
import com.github.aoreshin.shtatus.viewmodels.ConnectionListViewModel
import javax.inject.Inject
class ConnectionListFragment : Fragment() {
#Inject
lateinit var viewModelFactory: ViewModelProvider.Factory
private lateinit var refreshLayout: SwipeRefreshLayout
private lateinit var nameEt: EditText
private lateinit var urlEt: EditText
private lateinit var statusCodeEt: EditText
private lateinit var viewModel: ConnectionListViewModel
private lateinit var recyclerView: RecyclerView
private lateinit var viewAdapter: ConnectionListAdapter
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val view = inflater.inflate(R.layout.fragment_connection_list, container, false)
val application = (requireActivity().application as ShatusApplication)
application.appComponent.inject(this)
val viewModelProvider = ViewModelProvider(this, viewModelFactory)
viewModel = viewModelProvider.get(ConnectionListViewModel::class.java)
bindViews(view)
setupObservers()
setupListeners()
addFilterValues()
setupRecyclerView()
return view
}
private fun setupObservers() {
with(viewModel) {
getConnections().observe(viewLifecycleOwner, Observer { viewAdapter.submitList(it) })
getRefreshLiveData().observe(viewLifecycleOwner, Observer { status ->
when (status) {
ConnectionListViewModel.RefreshStatus.LOADING -> refreshLayout.isRefreshing = true
ConnectionListViewModel.RefreshStatus.READY -> refreshLayout.isRefreshing = false
else -> throwException(status.toString())
}
})
getNoMatchesEvent().observe(viewLifecycleOwner, Observer { showToast(R.string.status_no_matches) })
getEmptyTableEvent().observe(viewLifecycleOwner, Observer { showToast(R.string.status_no_connections) })
}
}
private fun setupRecyclerView() {
viewAdapter = ConnectionListAdapter(parentFragmentManager, ConnectionItemCallback())
recyclerView.apply {
layoutManager = LinearLayoutManager(context)
adapter = viewAdapter
}
}
private fun addFilterValues() {
with(viewModel) {
nameEt.setText(nameLiveData.value)
urlEt.setText(urlLiveData.value)
statusCodeEt.setText(actualStatusLiveData.value)
}
}
private fun bindViews(view: View) {
with(view) {
recyclerView = findViewById(R.id.recycler_view)
refreshLayout = findViewById(R.id.refresher)
nameEt = findViewById(R.id.nameEt)
urlEt = findViewById(R.id.urlEt)
statusCodeEt = findViewById(R.id.statusCodeEt)
}
}
private fun setupListeners() {
with(viewModel) {
refreshLayout.setOnRefreshListener { send() }
nameEt.addTextChangedListener { nameLiveData.value = it.toString() }
urlEt.addTextChangedListener { urlLiveData.value = it.toString() }
statusCodeEt.addTextChangedListener { actualStatusLiveData.value = it.toString() }
}
}
private fun throwException(status: String) {
throw IllegalStateException(getString(R.string.error_no_such_status) + status)
}
private fun showToast(resourceId: Int) {
Toast.makeText(context, getString(resourceId), Toast.LENGTH_SHORT).show()
}
override fun onDestroyView() {
super.onDestroyView()
with(viewModel) {
getNoMatchesEvent().removeObservers(viewLifecycleOwner)
getRefreshLiveData().removeObservers(viewLifecycleOwner)
getEmptyTableEvent().removeObservers(viewLifecycleOwner)
getConnections().removeObservers(viewLifecycleOwner)
}
}
}
How I should address this issue?

After some head scratching I've decided to go with internal ViewModel statuses, this way logic in Activity/Fragment is kept to a minimum.
So now my ViewModel looks like this:
package com.github.aoreshin.shtatus.viewmodels
import android.util.Log
import androidx.lifecycle.LiveData
import androidx.lifecycle.MediatorLiveData
import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.ViewModel
import com.github.aoreshin.shtatus.events.SingleLiveEvent
import com.github.aoreshin.shtatus.room.Connection
import io.reactivex.FlowableSubscriber
import io.reactivex.Single
import io.reactivex.android.schedulers.AndroidSchedulers
import io.reactivex.schedulers.Schedulers
import io.reactivex.subscribers.DisposableSubscriber
import okhttp3.ResponseBody
import retrofit2.Response
import java.util.function.Predicate
import javax.inject.Inject
import javax.inject.Singleton
#Singleton
class ConnectionListViewModel #Inject constructor(
private val connectionRepository: ConnectionRepository
) : ViewModel() {
private var tableStatus = TableStatus.OK
private val connections = connectionRepository.allConnections()
private val mediatorConnection = MediatorLiveData<List<Connection>>()
private val stopRefreshingEvent = SingleLiveEvent<Void>()
private val noMatchesEvent = SingleLiveEvent<Void>()
private val emptyTableEvent = SingleLiveEvent<Void>()
private val nameLiveData = MutableLiveData<String>()
private val urlLiveData = MutableLiveData<String>()
private val statusLiveData = MutableLiveData<String>()
init {
with(mediatorConnection) {
addSource(connections) { update() }
addSource(nameLiveData) { update() }
addSource(urlLiveData) { update() }
addSource(statusLiveData) { update() }
}
}
fun getStopRefreshingEvent(): LiveData<Void> = stopRefreshingEvent
fun getNoMatchesEvent(): LiveData<Void> = noMatchesEvent
fun getEmptyTableEvent(): LiveData<Void> = emptyTableEvent
fun getConnections(): LiveData<List<Connection>> = mediatorConnection
fun getName(): String? = nameLiveData.value
fun getUrl(): String? = urlLiveData.value
fun getStatus(): String? = statusLiveData.value
fun setName(name: String) { nameLiveData.value = name }
fun setUrl(url: String) { urlLiveData.value = url }
fun setStatus(status: String) { statusLiveData.value = status }
private fun update() {
if (connections.value != null) {
if (connections.value.isNullOrEmpty()) {
if (tableStatus != TableStatus.EMPTY) {
emptyTableEvent.call()
tableStatus = TableStatus.EMPTY
}
} else {
mediatorConnection.value = connections.value?.filter { connection -> getPredicate().test(connection) }
if (mediatorConnection.value.isNullOrEmpty()) {
if (tableStatus != TableStatus.NO_MATCHES) {
noMatchesEvent.call()
tableStatus = TableStatus.NO_MATCHES
}
} else {
tableStatus = TableStatus.OK
}
}
}
}
fun send() {
if (!connections.value.isNullOrEmpty()) {
val singles = connections.value?.map { connection ->
val id = connection.id
val description = connection.description
val url = connection.url
var message = ""
connectionRepository.sendRequest(url)
.doOnSuccess { message = it.code().toString() }
.doOnError { message = it.message!! }
.doFinally {
val result = Connection(id, description, url, message)
connectionRepository.insert(result)
}
}
Single.mergeDelayError(singles)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.doFinally { stopRefreshingEvent.call() }
.subscribe(getSubscriber())
} else {
stopRefreshingEvent.call()
}
}
private fun getSubscriber() : FlowableSubscriber<Response<ResponseBody>> {
return object: DisposableSubscriber<Response<ResponseBody>>() {
override fun onComplete() { Log.d(TAG, "All requests sent") }
override fun onNext(t: Response<ResponseBody>?) { Log.d(TAG, "Request is done") }
override fun onError(t: Throwable?) { Log.d(TAG, t!!.message!!) }
}
}
private fun getPredicate(): Predicate<Connection> {
return Predicate { connection ->
connection.description.contains(nameLiveData.value.toString(), ignoreCase = true)
&& connection.url.contains(urlLiveData.value.toString(), ignoreCase = true)
&& connection.actualStatusCode.contains(
statusLiveData.value.toString(),
ignoreCase = true
)
}
}
private enum class TableStatus {
NO_MATCHES,
EMPTY,
OK
}
companion object {
private const val TAG = "ConnectionListViewModel"
}
}
And corresponding Fragment looks like this:
package com.github.aoreshin.shtatus.fragments
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.EditText
import android.widget.Toast
import androidx.core.widget.addTextChangedListener
import androidx.fragment.app.Fragment
import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModelProvider
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import androidx.swiperefreshlayout.widget.SwipeRefreshLayout
import com.github.aoreshin.shtatus.R
import com.github.aoreshin.shtatus.ShatusApplication
import com.github.aoreshin.shtatus.viewmodels.ConnectionListViewModel
import javax.inject.Inject
class ConnectionListFragment : Fragment() {
#Inject
lateinit var viewModelFactory: ViewModelProvider.Factory
private lateinit var refreshLayout: SwipeRefreshLayout
private lateinit var nameEt: EditText
private lateinit var urlEt: EditText
private lateinit var statusCodeEt: EditText
private lateinit var viewModel: ConnectionListViewModel
private lateinit var recyclerView: RecyclerView
private lateinit var viewAdapter: ConnectionListAdapter
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val view = inflater.inflate(R.layout.fragment_connection_list, container, false)
val application = (requireActivity().application as ShatusApplication)
application.appComponent.inject(this)
val viewModelProvider = ViewModelProvider(this, viewModelFactory)
viewModel = viewModelProvider.get(ConnectionListViewModel::class.java)
bindViews(view)
setupObservers()
setupListeners()
addFilterValues()
setupRecyclerView()
return view
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
if (savedInstanceState != null) {
refreshLayout.isRefreshing = savedInstanceState.getBoolean(REFRESHING, false)
}
}
private fun setupObservers() {
with(viewModel) {
getConnections().observe(viewLifecycleOwner, Observer { viewAdapter.submitList(it) })
getStopRefreshingEvent().observe(viewLifecycleOwner, Observer { refreshLayout.isRefreshing = false })
getNoMatchesEvent().observe(viewLifecycleOwner, Observer { showToast(R.string.status_no_matches) })
getEmptyTableEvent().observe(viewLifecycleOwner, Observer { showToast(R.string.status_no_connections) })
}
}
private fun setupRecyclerView() {
viewAdapter = ConnectionListAdapter(parentFragmentManager, ConnectionItemCallback())
recyclerView.apply {
layoutManager = LinearLayoutManager(context)
adapter = viewAdapter
}
}
private fun addFilterValues() {
with(viewModel) {
nameEt.setText(getName())
urlEt.setText(getUrl())
statusCodeEt.setText(getStatus())
}
}
private fun bindViews(view: View) {
with(view) {
recyclerView = findViewById(R.id.recycler_view)
refreshLayout = findViewById(R.id.refresher)
nameEt = findViewById(R.id.nameEt)
urlEt = findViewById(R.id.urlEt)
statusCodeEt = findViewById(R.id.statusCodeEt)
}
}
private fun setupListeners() {
with(viewModel) {
refreshLayout.setOnRefreshListener { send() }
nameEt.addTextChangedListener { setName(it.toString()) }
urlEt.addTextChangedListener { setUrl(it.toString()) }
statusCodeEt.addTextChangedListener { setStatus(it.toString()) }
}
}
override fun onSaveInstanceState(outState: Bundle) {
super.onSaveInstanceState(outState)
outState.putBoolean(REFRESHING, refreshLayout.isRefreshing)
}
private fun showToast(resourceId: Int) {
Toast.makeText(context, getString(resourceId), Toast.LENGTH_SHORT).show()
}
override fun onDestroyView() {
super.onDestroyView()
with(viewModel) {
getNoMatchesEvent().removeObservers(viewLifecycleOwner)
getEmptyTableEvent().removeObservers(viewLifecycleOwner)
getStopRefreshingEvent().removeObservers(viewLifecycleOwner)
getConnections().removeObservers(viewLifecycleOwner)
}
}
companion object {
private const val REFRESHING = "isRefreshing"
}
}
Pros
No additional dependencies
Usage of widespread SingleLiveEvent
Pretty straightforward to implement
Cons
Conditional logic is quickly getting out of hand even in this simple case, surely needs refactoring. Not sure if this approach will work in real-life complex scenarios.
If there are cleaner and more concise approaches to solve this problem I will be happy to hear about them!

In your solution; you introduced TableStatus which is acting like flag and not needed.
If you really looking for a good Android Architecture; instead you could just do
if (viewLifecycleOwner.lifecycle.currentState == Lifecycle.State.RESUMED) {
showToast(R.string.status_no_connections)
and
if (viewLifecycleOwner.lifecycle.currentState == Lifecycle.State.RESUMED) {
showToast(R.string.status_no_matches)
NOTE:
viewLifecycleOwner.lifecycle.currentState == Lifecycle.State.RESUMED
is not a patch Google implemented this fix in support library as well.
And remove #Singleton from (why would you need it to be singleton)
#Singleton
class ConnectionListViewModel #Inject constructor(
PS:
From the top of my head looks like; you may also don't need SingleLiveEvent for you case.
(would love to talk more on this if you want I also just have started Kotlin + Clear & Scalable Android Architecture)