I am putting myself in a RecycleView from Java to Kotlin. I am trying to keep state between screen rotations. But it is not working. Here my code:
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import androidx.lifecycle.ViewModel
import androidx.lifecycle.ViewModelProvider
//import androidx.lifecycle.ViewModelProviders
import kotlinx.android.synthetic.main.activity_main.*
class MainActivity : AppCompatActivity() {
private lateinit var viewModel: ScoreViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
viewModel = ViewModelProvider.NewInstanceFactory().create(ScoreViewModel::class.java)
//viewModel = ViewModelProviders.of(this).get(ScoreViewModel::class.java)
println("-> "+viewModel.scoreTeamA);
}
fun addOneForTeamA(view: View) {
viewModel.scoreTeamA++
displayForTeamA()
}
fun addTwoForTeamA(view: View) {
viewModel.scoreTeamA += 2
displayForTeamA()
}
fun addThreeForTeamA(view: View) {
viewModel.scoreTeamA += 3
displayForTeamA()
}
fun addOneForTeamB(view: View) {
++viewModel.scoreTeamB
displayForTeamB()
}
fun addTwoForTeamB(view: View) {
viewModel.scoreTeamB += 2
displayForTeamB()
}
fun addThreeForTeamB(view: View) {
viewModel.scoreTeamB += 3
displayForTeamB()
}
fun displayForTeamA(){
team_a_score.text = viewModel.scoreTeamA.toString()
}
fun displayForTeamB(){
team_b_score.text = viewModel.scoreTeamB.toString()
}
fun resetScore(view: View) {
viewModel.scoreTeamA = 0
viewModel.scoreTeamB = 0
displayForTeamA()
displayForTeamB()
}
}
import androidx.lifecycle.ViewModel
class ScoreViewModel : ViewModel() {
var scoreTeamA: Int = 0
var scoreTeamB: Int = 0
}
Another question is why in one project ViewModelProviders.of appears as deprecated (se commented lines) and in another project with similar gradle dependencies it is OK.
Thanks in advance!
Using ViewModelProvider.NewInstanceFactory().create is going to create a new instance each time - this is never the right thing to use. Instead, follow the ViewModelProviders.of() deprecation message:
Use the by viewModels() Kotlin property delegate or ViewModelProvider(ViewModelStoreOwner), passing in the activity.
viewModel = new ViewModelProvider(this).get(ScoreViewModel::class.java)
Related
I am having some issues with Firebase auth. I'm building an app using using Kotlin but keep retrieving the error 'W/System: Ignoring header X-Firebase-Locale because its value was null.'
I had this working previously, when I had set up the application using activities. I've now moved towards MVP architecture, but this seems to have broken my firebase authentication. I have also ensured that Email/Password sign in method has been enabled in the Firebase console.
If anyone could please take a look and hopefully you can see where I am going wrong. Many thanks.
SignInView
package org.wit.hikingtrails.views.signIn
import android.content.Intent
import android.os.Bundle
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import org.wit.hikingtrails.databinding.ActivitySignInBinding
import com.google.firebase.auth.FirebaseAuth
import org.wit.hikingtrails.activities.SignUpActivity
import org.wit.hikingtrails.views.hikeList.HikeListView
import org.wit.hikingtrails.views.signUp.SignUpView
class SignInView : AppCompatActivity() {
lateinit var presenter: SignInPresenter
private lateinit var binding: ActivitySignInBinding
private lateinit var firebaseAuth: FirebaseAuth
override fun onCreate(savedInstanceState: Bundle?) {
presenter = SignInPresenter( this)
super.onCreate(savedInstanceState)
binding = ActivitySignInBinding.inflate(layoutInflater)
setContentView(binding.root)
firebaseAuth = FirebaseAuth.getInstance()
binding.textView.setOnClickListener {
val intent = Intent(this, SignUpView::class.java)
startActivity(intent)
}
binding.button.setOnClickListener {
val email = binding.emailEt.text.toString()
val pass = binding.passET.text.toString()
if (email.isNotEmpty() && pass.isNotEmpty()) {
presenter.doLogin(email, pass)
} else {
Toast.makeText(this, "Empty Fields Are not Allowed !!", Toast.LENGTH_SHORT).show()
}
}
}
override fun onStart() {
super.onStart()
if(firebaseAuth.currentUser != null){
val intent = Intent(this, HikeListView::class.java)
startActivity(intent)
}
}
}
SignInPresenter:
package org.wit.hikingtrails.views.signIn
import android.content.ContentValues.TAG
import android.content.Intent
import android.util.Log
import androidx.activity.result.ActivityResultLauncher
import androidx.activity.result.contract.ActivityResultContracts
import com.google.firebase.auth.FirebaseAuth
import org.wit.hikingtrails.views.hikeList.HikeListView
import timber.log.Timber
import timber.log.Timber.i
class SignInPresenter (val view: SignInView) {
private lateinit var loginIntentLauncher : ActivityResultLauncher<Intent>
init{
registerLoginCallback()
}
var auth: FirebaseAuth = FirebaseAuth.getInstance()
fun doLogin(email: String, pass: String) {
// view.showProgress()
auth.signInWithEmailAndPassword(email, pass).addOnCompleteListener(view) { task ->
if (task.isSuccessful) {
val launcherIntent = Intent(view, HikeListView::class.java)
loginIntentLauncher.launch(launcherIntent)
} else {
i("Login failed:")
// val launcherIntent = Intent(view, HikeListView::class.java)
// loginIntentLauncher.launch(launcherIntent)
}
// view.hideProgress()
}
}
private fun registerLoginCallback(){
loginIntentLauncher =
view.registerForActivityResult(ActivityResultContracts.StartActivityForResult())
{ }
}
}
For anyone that was having the same issue: The issue was with my API key. In kotlin, to debug, I used Timber.i( "signInWithCredential:failure ${task.exception?.message}") within the else statement of doLogin() in the presenter
The error that appears is as follows "Type mismatch: inferred type is String? but String is expected". How can I solve this problem?
The source code is as follows:
package com.example.submission2.Activity
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.lifecycle.ViewModel
import androidx.lifecycle.ViewModelProvider
import com.bumptech.glide.Glide
import com.bumptech.glide.load.resource.drawable.DrawableTransitionOptions
import com.example.submission2.Adapter.AdapterSectionPager
import com.example.submission2.ViewModel.DetailVM
import com.example.submission2.databinding.ActivityDetailBinding
class DetailActivity : AppCompatActivity() {
companion object{
const val EXTRA_USERNAME = "extra_username"
}
private lateinit var binding: ActivityDetailBinding
private lateinit var viewModel: DetailVM
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityDetailBinding.inflate(layoutInflater)
setContentView(binding.root)
supportActionBar?.apply {
setDisplayHomeAsUpEnabled(true)
setDisplayShowHomeEnabled(true)
}
val username = intent.getStringExtra(EXTRA_USERNAME)
viewModel = ViewModelProvider(this, ViewModelProvider.NewInstanceFactory()).get(DetailVM::class.java)
viewModel.setPenggunaDetail(username)
viewModel.getPenggunaDetail().observe(this) {
if (it != null) {
binding.apply {
tvNamaDetail.text = it.name
tvUsernameDetail.text = it.login
tvCompanyDetail.text = it.company
tvEmailDetail.text = it.email
tvFollowersDetail.text = "${it.followers} Followers"
tvFollowingDetail.text = "${it.following} Follwing"
Glide.with(this#DetailActivity)
.load(it.avatar_url)
.transition(DrawableTransitionOptions.withCrossFade())
.centerCrop()
.into(ivDetailProfil)
}
}
}
val sectionPagerAdpter = AdapterSectionPager(this,supportFragmentManager)
binding.apply {
viewPager.adapter = sectionPagerAdpter
tabs.setupWithViewPager(viewPager)
}
}
}
error appears on the line "viewModel.set User Data(username)" username is used in extra_username which will be called in main
for main activity as follows:
package com.example.submission2.Activity
import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.KeyEvent
import android.view.View
import androidx.lifecycle.ViewModelProvider
import androidx.recyclerview.widget.LinearLayoutManager
import com.example.submission2.Adapter.AdapterPengguna
import com.example.submission2.DataBase.Pengguna
import com.example.submission2.R
import com.example.submission2.ViewModel.MainVM
import com.example.submission2.databinding.ActivityMainBinding
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
private lateinit var viewModel: MainVM
private lateinit var adapter: AdapterPengguna
private fun searchPengguna(){
binding.apply {
val query = etSearch.text.toString()
if (query.isEmpty())return
showLoading(true)
viewModel.setSearchPengguna(query)
}
}
private fun showLoading(state: Boolean){
if (state){
binding.progressBarMain.visibility = View.VISIBLE
}else{
binding.progressBarMain.visibility = View.GONE
}
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
adapter = AdapterPengguna()
adapter.notifyDataSetChanged()
adapter.setOnItemClickCallback(object :AdapterPengguna.OnItemClickCallback{
override fun onItemCliked(data: Pengguna) {
Intent(this#MainActivity,DetailActivity::class.java).also {
it.putExtra(DetailActivity.EXTRA_USERNAME, data.login)
startActivity(it)
}
}
})
viewModel = ViewModelProvider(this,ViewModelProvider.NewInstanceFactory()).get(MainVM::class.java)
binding.apply {
rvPengguna.layoutManager = LinearLayoutManager(this#MainActivity)
rvPengguna.setHasFixedSize(true)
rvPengguna.adapter = adapter
btnSearch.setOnClickListener {
searchPengguna()
}
etSearch.setOnKeyListener { v, keyCode, event ->
if (event.action == KeyEvent.ACTION_DOWN && keyCode == KeyEvent.KEYCODE_ENTER){
searchPengguna()
return#setOnKeyListener true
}
return#setOnKeyListener false
}
}
viewModel.getSearchPengguna().observe(this,{
if (it!= null){
adapter.setList(it)
showLoading(false
)
}
})
}
}
In your code there is no such line as viewModel.setUserData
I guess that the error occurs in the line viewModel.setPenggunaDetail(username)
In this case, you should pay attention to the fact that the all intent.getExtra calls returns nullable values.
Thus, if the setPenggunaDetail call expects a non-nullable argument, you must first check username value for null
This is my first post and I am brand new to coding so please let me know if I've missed anything for getting some help.
I'm taking the Google Android Dev tutorials. The tutorial is walking me through creating a dice roll app. I completed that and for an extra challenge practice at the end it recommends getting two results from one button click.
I tried doing that in this code:
package com.example.diceroller
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.TextView
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val rollButton: Button = findViewById(R.id.button)
rollButton.setOnClickListener { rollDice() }
rollButton.setOnClickListener { rollDice2() }
}
private fun rollDice() {
val dice = Dice(6)
val diceRoll = dice.roll()
val resultTextView: TextView = findViewById(R.id.textView)
resultTextView.text = diceRoll.toString()
}
private fun rollDice2() {
val dice2 = Dice2(6)
val diceRoll2 = dice2.roll2()
val resultTextView: TextView = findViewById(R.id.textView2)
resultTextView.text = diceRoll2.toString()
}
}
class Dice(private val numSides: Int) {
fun roll(): Int {
return (1..numSides).random()
}
}
class Dice2(private val numSides: Int) {
fun roll2(): Int {
return (1..numSides).random()
}
}
I don't get any errors, but when I run the app it only shows one result (the second result). Again, I'm new to all this and maybe I'll learn it later, but looking for some help on why it only spits out one result. Any help is greatly appreciated and thank you in advance.
It's not made clear by the documentation for setOnClickListener, but a View (which a Button is a type of) can only have one click listener. So when you do this:
rollButton.setOnClickListener { rollDice() }
rollButton.setOnClickListener { rollDice2() }
you're setting a listener that calls rollDice(), and then replacing it with another one that calls rollDice2(). You need to do everything in a single listener!
rollButton.setOnClickListener {
rollDice()
rollDice2()
}
so when you click the button, it'll run the code in that lambda function you're passing in as your listener, so it'll call rollDice() and then rollDice2().
As a general rule, if a function is named like setListener, with a set, then it's usually a single listener that you can set (or unset, usually with null). If it's named something like addListener, with an add, that implies you can add more to what's already there, i.e. you can have multiple listeners or whatever.
I'm not saying this will always be true (always check the documentation, or the source code if you can! See what it's actually doing) but it's a good rule of thumb in my experience - but you should always check if you're unsure!
You can also achieve the same result by rolling the same dice twice
package com.example.diceroller
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.TextView
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val rollButton: Button = findViewById(R.id.button)
// setOnClickListner -> defines what to execute on button click
rollButton.setOnClickListener { rollDice() }
}
private fun rollDice() {
// create two dice's each with '6' sides
var dice_1 = Dice(6)
var dice_2 = Dice(6)
// roll the two dice's
val dice_1_roll = dice_1.roll()
val dice_2_roll = dice_2.roll()
// bind the obtained result to the corresponding 'textView'
val resultTextView_1: TextView = findViewById(R.id.textView)
val resultTextView_2: TextView = findViewById(R.id.textView)
// fun roll() in Dice: Class return 'Int' so convert into 'String'
resultTextView_1.text = dice_1_roll.toString()
resultTextView_2.text = dice_2_roll.toString()
}
}
class Dice(private val numSides: Int) {
fun roll(): Int {
return (1..numSides).random()
}
}
package com.example.diceroller
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.TextView
/**
* This activity allows the user to roll a dice and view the result
* on the screen.
*/
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val rollButton: Button = findViewById(R.id.button)
rollButton.setOnClickListener { rollDice() }
}
/**
* Roll the dice and update the screen with the result.
*/
private fun rollDice() {
// Create new Dice object with 6 sides and roll it
val myFirstDice = Dice(6)
val diceRollFirst = myFirstDice.roll()
// Update the screen with the dice roll
val resultTextView: TextView = findViewById(R.id.textView)
resultTextView.text = diceRollFirst.toString()
val mySecondDice = Dice(6)
val diceRollSecond = mySecondDice.roll()
val resultTextView2: TextView = findViewById(R.id.textView2)
resultTextView2.text = diceRollSecond.toString()
}
class Dice(private val numSides: Int) {
fun roll(): Int {
return (1..numSides).random()
}
}
}
I created a new empty activity for my project but I am getting an error. The activity file as well as the layout file is shown in red color. I tried creating an intent object from MainActivity, in order to start this activity but received the following error
Classifier 'Details' does not have a companion object, and thus must
be initialized here
I've attached a screenshot of my android studio.
Code for new activity
package com.example.safetyapp
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
class Details : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_details)
}
}
package com.example.safetyapp
import android.content.Intent
import android.os.Bundle
import android.widget.Button
import androidx.appcompat.app.AppCompatActivity
import com.firebase.ui.auth.AuthUI
import com.google.firebase.auth.FirebaseAuth
class MainActivity : AppCompatActivity() {
final val AUTH_REQUEST_CODE = 7192
lateinit var firebaseAuth:FirebaseAuth
lateinit var listener: FirebaseAuth.AuthStateListener
lateinit var providers: List<AuthUI.IdpConfig>
override fun onStart(){
super.onStart()
firebaseAuth.addAuthStateListener(listener)
}
override fun onStop(){
super.onStop()
if(listener!=null){
firebaseAuth.removeAuthStateListener(listener)
}
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val button2 = findViewById<Button>(R.id.button2)
val defence = findViewById<Button>(R.id.Defence)
button2.setOnClickListener{
val myintent = Intent(this, Details::class.java)
}
init()
}
private fun init() {
providers = arrayListOf(AuthUI.IdpConfig.PhoneBuilder().build(),
AuthUI.IdpConfig.EmailBuilder().build())
firebaseAuth = FirebaseAuth.getInstance()
listener = object:FirebaseAuth.AuthStateListener{
override fun onAuthStateChanged(p0: FirebaseAuth) {
val user = p0.currentUser
if(user!= null){
// Do something
}
else{
startActivityForResult(AuthUI.getInstance()
.createSignInIntentBuilder()
.setAvailableProviders(providers)
.setLogo(R.drawable.logo)
.build(),AUTH_REQUEST_CODE)
}
}
}
}
}
You didn't import the Details class, add this line between your MainActivity class imports
import com.example.safetyapp.Details
if I any change in firebase like delete, update. The data in recyclerView is duplicated if any of those CRUD occur, so I added temporary swipeRefresh to refresh the activity but this solution doesn't make sense.
This image below explain when I update data in firebase and what happend in RecyclerView
MainDashBoard.kt
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.database.DataSnapshot
import com.google.firebase.database.DatabaseError
import com.google.firebase.database.FirebaseDatabase
import com.google.firebase.database.ValueEventListener
import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.os.Handler
import android.os.Looper
import android.view.Menu
import android.view.MenuItem
import android.view.View
import android.widget.ProgressBar
import android.widget.TextView
import android.widget.Toast
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import androidx.swiperefreshlayout.widget.SwipeRefreshLayout
class MainDashBoard : AppCompatActivity(), OnItemPatientClickListener{
data class PatientDataItem(val patientName: String, val patientMessage: String)
private lateinit var auth: FirebaseAuth
lateinit var swipeRefreshLayout: SwipeRefreshLayout
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main_dash_board)
var database = FirebaseDatabase.getInstance().reference
var patientDataItems = ArrayList<PatientDataItem>()
val patientRecycler = findViewById<RecyclerView>(R.id.patient_recycler)
val patienDashboardprogressBar = findViewById<ProgressBar>(R.id.patientDashboardprogressBar)
val noDataMain = findViewById<TextView>(R.id.no_data_main_dashboard)
swipeRefreshLayout = findViewById(R.id.swipe)
patientRecycler.layoutManager = LinearLayoutManager(this)
patientRecycler.adapter = MainDashboardAdapter(patientDataItems, this)
auth = FirebaseAuth.getInstance()
val user = auth.currentUser
val patientsListener = object : ValueEventListener {
override fun onDataChange(p0: DataSnapshot) {
val patients = p0.child("users").child(user!!.uid)
if (p0.value == null ){
noDataMain.visibility = View.VISIBLE
}else{
noDataMain.visibility = View.GONE
for (i in p0.children){
var patientName = i.key.toString()
var patientMessage = i.value.toString()
patientDataItems.add(PatientDataItem(patientName, patientMessage))
}
}
patientRecycler.scrollToPosition(patientDataItems.size-1)
patienDashboardprogressBar.visibility = View.GONE
}
override fun onCancelled(error: DatabaseError) {
println("error")
}
}
database.child("location").child("users").child(user!!.uid).addValueEventListener(patientsListener)
// database.child("location").addValueEventListener(postListener)
swipeRefreshLayout.setOnRefreshListener {
startActivity(intent);
Handler(Looper.getMainLooper()).postDelayed(Runnable {
swipeRefreshLayout.isRefreshing = false
}, 4000)
}
}
override fun onItemClick(patientDataItems: PatientDataItem) {
val patientMacAddressName = patientDataItems.patientName
val dashboardIntent = Intent(this, DashboardActivity::class.java)
dashboardIntent.putExtra("macAddressNamePatient", patientMacAddressName)
startActivity(dashboardIntent)
}
}
MainDashBoardAdapter.kt
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import androidx.constraintlayout.widget.ConstraintLayout
import androidx.recyclerview.widget.RecyclerView
import com.example.ard_here.R
class MainDashboardAdapter(private val patientDataSet: ArrayList<MainDashBoard.PatientDataItem>,
private val onPatientClickListener: OnItemPatientClickListener): RecyclerView.Adapter<MainDashboardAdapter.PatientCustomHolder>(){
override fun getItemCount(): Int {
return patientDataSet.size
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): PatientCustomHolder {
var layoutInflater = LayoutInflater.from(parent?.context)
var cellForRow = layoutInflater.inflate(R.layout.main_patient_layout, parent, false)
return PatientCustomHolder(cellForRow)
}
override fun onBindViewHolder(holder: PatientCustomHolder, position: Int) {
holder.bindItems(patientDataSet[position])
holder.patientLayout.setOnClickListener {
onPatientClickListener.onItemClick(patientDataSet[position])
}
}
class PatientCustomHolder(v: View): RecyclerView.ViewHolder(v){
val patientLayout: ConstraintLayout = v.findViewById(R.id.patient_layout)
val patientName: TextView = v.findViewById(R.id.patient_name)
val patientMessage : TextView = v.findViewById(R.id.patient_message)
fun bindItems(data_item: MainDashBoard.PatientDataItem){
patientName.text = data_item.patientName
patientMessage.text = data_item.patientMessage
}
}
}
OnItemPatientClickListener.kt
interface OnItemPatientClickListener {
fun onItemClick(patientDataItems: MainDashBoard.PatientDataItem)
}
clear your data container then bind it again in recyclerview.
or you have mvvm pattern, you can use live data to observe data source and if there is any changes, your activity will easily notified and make some ui changes
Since you're reading the data with addValueEventListener, which means that:
The data from the path is read from the database right away, and passed to your onDataChange.
The client the continues monitor the path, and if anything changes it calls your onDataChange again with all data at the path.
In your onDataChange you're only ever adding data to patientDataItems. That works well the first time the data is loaded, so #1 above. But if you add or change a single child node (#2 above), you get called with all data at the path again. So that's when you end up duplicating the items in the view.
The simplest solution is to clear patientDataItems whenever onDataChange get called:
override fun onDataChange(p0: DataSnapshot) {
patientDataItems.clear()
...