Develop Reference

How can i delete something from cloud firestore database?

i'm trying to delete a document in my firestore database
i'm using a listview to list some things of my data base, the items of this listview have a delete button, what i want is: when the user presses the delete button, this thing gets deleted from the list and from the firestore, there what i'm trying:
this is my entire activity to do this:
class RigBuilderActivity : AppCompatActivity() {
lateinit var botaoAddPc: FloatingActionButton
lateinit var pcName:EditText
lateinit var infoButton:FloatingActionButton
lateinit var pcListView: ListView
companion object{
const val TAG = "RigBuilderActivity"
}
var pc = arrayListOf<PC>()
val pcAdapter = PcAdapter()
val db = Firebase.firestore
val userId = FirebaseAuth.getInstance().currentUser!!.uid
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_rig_builder)
botaoAddPc = findViewById(R.id.rig_builder_button_add_pc)
pcName = findViewById(R.id.rig_builder_text_input)
infoButton = findViewById(R.id.rig_builder_button_info)
pcListView = findViewById(R.id.rig_builder_pc_list)
botaoAddPc.setOnClickListener{
var pc_text :String = pcName.text.toString()
val computer = PC(UUID.randomUUID().toString(),pc_text)
db.collection("users").document(userId).collection("PC").add(computer.toHashmapPC()).addOnSuccessListener { task->
Log.d(TAG, "DocumentSnapshot added with ID: ${task.id}")
Toast.makeText(this,"Pc added",Toast.LENGTH_SHORT).show()
}.addOnFailureListener{ e->
Log.w(TAG,"Error Adding PC",e)
Toast.makeText(this,"Failed",Toast.LENGTH_SHORT).show()
}
}
pcListView.adapter = pcAdapter
db.collection("users").document(userId).collection("PC").addSnapshotListener{ value, e->
if (e!=null){
Log.w(TAG,"Listen failed.",e)
return#addSnapshotListener
}
pc.clear()
for (doc in value!!){
val pc = PC.fromQueryDoc(doc)
this.pc.add(pc)
}
pcAdapter.notifyDataSetChanged()
}
}
fun getPcName():String{
return pcName.toString()
}
inner class PcAdapter : BaseAdapter() {
override fun getCount(): Int {
return pc.size
}
override fun getItem(p0: Int): Any {
return pc[p0]
}
override fun getItemId(p0: Int): Long {
return 0
}
override fun getView(p0: Int, p1: View?, p2: ViewGroup?): View {
val rootView = layoutInflater.inflate(R.layout.pc_item_layout, p2,false )
val textViewPcName = rootView.findViewById<TextView>(R.id.pc_name)
val editButton = rootView.findViewById<ImageButton>(R.id.pc_edit_button)
val deleteButton = rootView.findViewById<FloatingActionButton>(R.id.pc_delete_button)
textViewPcName.text = pc[p0].counter.toString()
deleteButton.setOnClickListener{
val ref : DocumentReference = db.collection("users").document(userId).collection("PC").document(pc[p0].getPcId())
ref.delete().addOnSuccessListener {
Log.d(TAG,"Pc deleted with success")
Toast.makeText(this#RigBuilderActivity,"Deleted with success",Toast.LENGTH_SHORT).show()
}
pcAdapter.notifyDataSetChanged()
}
editButton.setOnClickListener{
}
textViewPcName.text = pc[p0].name
return rootView
}
}
}
in case of needing, this is my PC class, i'm just using one of the constructors to test the list and make the delete works:
class PC {
var id:String
var name : String? = null
var counter : Long? = null
lateinit var cpu :CPU
lateinit var gpu: GPU
lateinit var motherBoard: MotherBoard
/**
* Construtor de teste
*/
constructor(id:String, name:String?){
this.id = id
this.name = name
}
/**
* Construtor ainda a implementar
*/
constructor(id:String, name:String?, cpu: CPU,gpu: GPU,motherBoard: MotherBoard){
this.id = id
this.name = name
this.cpu = cpu
this.gpu = gpu
this.motherBoard = motherBoard
}
fun toHashmapPC() : HashMap <String, Any?>{
return hashMapOf(
"id" to id,
"name" to name
)
}
fun getPcId():String{
return id
}
companion object{
fun fromQueryDoc(documentSnapshot: DocumentSnapshot):PC{
return PC(
documentSnapshot["id"] as String,
documentSnapshot["name"] as String
)
}
}
}

Error adding to mutable list (NPE) Kotlin Android

---Data Class---
trying to add object to meals MutableList-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
data class YelpRestaurant(
val name: String,
val rating: Double,
val price: String,
#SerializedName("review_count") val numReviews: Int,
#SerializedName("image_url") val imageUrl: String,
val categories: List<YelpCategory>,
val location: YelpLocation,
val meals: MutableList<UserMeals>
)
----EDITED ACTIVITY----
class ThoughtsActivity : AppCompatActivity() {
lateinit var mealName: String
lateinit var mealPrice: String
lateinit var mealThought: String
lateinit var selected_Restaurant : YelpRestaurant
val meals = mutableListOf<UserMeals>()
#Subscribe(sticky = true)
fun getRest(selectedRestaurant : YelpRestaurant) {
selected_Restaurant = selectedRestaurant
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_thoughts)
thoughtBtn.setOnClickListener() {
mealName = m_name.text.toString()
mealPrice = m_price.text.toString()
mealThought = m_thought.text.toString()
var addedMeal = UserMeals(mealName, mealPrice.toDouble(), mealThought)
if (mealName.isNotEmpty()) {
selected_Restaurant.meals.add(addedMeal)
}
}
}
override fun onStart() {
super.onStart()
EventBus.getDefault().register(this)
}
override fun onStop() {
super.onStop()
EventBus.getDefault().unregister(this)
}
}

You have null pointer exception when accessing selected_Restaurant.meals to prevent NPE change meals to val and instantiate it when you declare it like this in selected_Restaurant:
val meals = mutableListOf<UserMeals>()

How do I change the viewmodel observable data in android?

I created a gridView that has an ArrayAdapter, the gridView contains only photos, I am fetching the image url in an Array and I am observing the array through my activity. Here is my viewmodel
class ProfileViewModel constructor(): ViewModel() {
var first_name: String? = null
var last_name: String? = null
var dob: String? = null
var address: String? = null
var organization: String? = null
var hobby: String? = null
var bio: String? = null
var imagePath: String = ""
private val imageList : MutableLiveData<ArrayList<ProfileViewModel>> = MutableLiveData()
constructor(photo : Photo) : this() {
this.imagePath = photo.imageUrl
}
fun getImageUrl() : String {
return imagePath
}
companion object {
#BindingAdapter("imageUrl")
#JvmStatic
fun loadImage(imageView: ImageView, imageUrl: String) {
Glide.with(imageView.context)
.load(imageUrl)
.apply(RequestOptions.centerCropTransform())
.placeholder(R.drawable.ic_add_icon)
.into(imageView)
}
}
val profileViewModels : MutableLiveData<ArrayList<ProfileViewModel>>
get() {
val profileViewModels = ArrayList<ProfileViewModel>()
val photo1 = Photo("")
val profileVM = ProfileViewModel(photo1)
repeat(6) {
profileViewModels.add(profileVM)
}
imageList.value = profileViewModels
return imageList
}
}
}
Here is my activity where I am observing the data
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
val binding: ActivityProfileBinding =
DataBindingUtil.setContentView(this, R.layout.activity_profile)
val viewModel = ViewModelProvider(this).get(ProfileViewModel::class.java)
viewModel.profileViewModels.observe(this,
Observer<ArrayList<ProfileViewModel>> { image_paths ->
Log.d("added", "$image_paths")
val imageAdapter = ImageAdapter(this#Profile, R.layout.image_card, image_paths!!)
gridView.adapter = imageAdapter
})
}
I am getting images in the gridView but I want to update the observable value on gridView Item click in the clicked position. How do I do that?

First, you can create a function in viewmodel, that you want to do when clicked. for example:
private fun doSomethingWhenClicked(listPosition: Int){
val clickedImage = profileViewModels[position]
//do something here for clicked image
//..
}
Then, initialize the viewmodel in adapter like this. So you can update your profileViewModels in onClickListener inside the ImageAdapter
viewmodel.doSomethingWhenClicked(position)
Hope this answer you!

Kotlin RecyclerView no adapter attached skipping layout

I don't know what the problem is but same code works fine in java
Here is my adapter class:
class MainAdapter(private val context: Context, private val firebaseVisionlabel: ArrayList<FirebaseVisionLabel>) : RecyclerView.Adapter<CustomViewHolder>() {
override fun getItemCount(): Int {
return firebaseVisionlabel.size
}
override fun onCreateViewHolder(p0: ViewGroup, p1: Int): CustomViewHolder {
val v = LayoutInflater.from(context).inflate(R.layout.list_items,p0,false)
return CustomViewHolder(v)
}
override fun onBindViewHolder(p0: CustomViewHolder, p1: Int) {
val firebaseVisionLabel = firebaseVisionlabel?.get(p1)
val label = firebaseVisionLabel?.label
val confidence =firebaseVisionLabel?.confidence.toString()
p0.itemView.textView.text = label
p0.itemView.confidence.text = confidence
}
}
class CustomViewHolder(v:View) : RecyclerView.ViewHolder(v)
MainActivity: (Global declaration)
var fileUri: Uri? = null
var TAG = "MainActivity"
var firebaseVisionLabels : ArrayList<FirebaseVisionLabel>? = null
In onCreate :
rec_view.layoutManager = LinearLayoutManager(this)
rec_view.setHasFixedSize(true)
Button :
detect_button.setOnClickListener{
imageRecognition()
}
Function :
private fun imageRecognition() {
var bitmap = MediaStore.Images.Media.getBitmap(this.contentResolver, fileUri)
var image = FirebaseVisionImage.fromBitmap(bitmap)
val labeler = FirebaseVision.getInstance().visionLabelDetector
labeler.detectInImage(image)
.addOnSuccessListener { labels ->
for (label in labels) {
val text = label.label
val entityId = label.entityId
val confidence = label.confidence
Log.d("TAG", "$text $confidence") //logcat works
firebaseVisionLabels?.add(label)
//Main problem??
rec_view.adapter = firebaseVisionLabels?.let { MainAdapter(this, it) }
}
}.addOnFailureListener { e ->
// Task failed with an exception
// ...
detect_button.isEnabled = true
Log.d(TAG,e.toString())
}
}
Logcat prints the expected outputs but I don't know what the problem is in recyclerview. I don't want to put bunch of camera and gallery intents codes, they works fine. Thanks for helping.

I solved by changing RecyclerView to BaseAdapter and the parameter to ArrayList. I guess RecyclerView can work same with the Basedapter by changing the parameter private val firebaseVisionlabel: ArrayList<FirebaseVisionLabel> to private val labeltext : ArrayList<String> I think it is a bug between FirebaseVisionLabel and Kotlin
Modified part for MainActivity :
for (label in labels) {
for(i in 1..1){
val text = label.label
val entityId = label.entityId
val confidence = label.confidence
new_list.add(text)
}
list_view.adapter =MainAdapter(this,new_list)

Typecasting Error in Kotlin: ArrayList

I am creating a music player app, In which there are a recycler view and many fragments. I am getting an error on my MainScreenFragment.kt file. I checked the error log and the error its shows is:
******Caused by: kotlin.TypeCastException: null cannot be cast to non-null type
kotlin.collections.ArrayList /* =
java.util.ArrayList */
at
com.thepanku.musicplayer.Fragments.MainScreenFragment.onCreateView(MainScreenFragment.kt:60)
at
android.support.v4.app.Fragment.performCreateView(Fragment.java:2354)******
what would be the reason for the error, any help would be appreciable. I am fed up with the error.
Here is the code:
class MainScreenFragment : Fragment() {
var getSongList : ArrayList<Songs>? = null
var nowPlayingBottomBar: RelativeLayout?=null
var playPauseButton: ImageView?=null
var songTitle: TextView?=null
var visibleLayout: RelativeLayout?=null
var noSongs: RelativeLayout?=null
var recyclerView: RecyclerView?= null
var myActivity:Activity?=null
var _mainScreenAdapter : MainScreenAdapter?=null
override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
val view = inflater?.inflate(R.layout.content_main, container, false)
setHasOptionsMenu(true)
activity.title = "All songs"
visibleLayout = view?.findViewById<RelativeLayout>(R.id.visibleLayout)
noSongs = view?.findViewById<RelativeLayout>(R.id.noSongs)
nowPlayingBottomBar = view?.findViewById<RelativeLayout>(R.id.hiddenBarMainScreen)
songTitle = view?.findViewById<TextView>(R.id.songTitleMainScreen)
playPauseButton = view?.findViewById<ImageButton>(R.id.playpauseButton)
(nowPlayingBottomBar as RelativeLayout).isClickable = false
recyclerView = view?.findViewById<RecyclerView>(R.id.contentMain)
visibleLayout?.visibility = View.INVISIBLE
noSongs?.visibility = View.VISIBLE
//getting error on this line->
_mainScreenAdapter = MainScreenAdapter(getSongList as ArrayList<Songs>, activity)
val mLayoutManager = LinearLayoutManager(activity)
(recyclerView as RecyclerView).layoutManager = mLayoutManager
(recyclerView as RecyclerView).itemAnimator = DefaultItemAnimator()
(recyclerView as RecyclerView).adapter = _mainScreenAdapter
return view
}
fun getSongsFromPhone(): ArrayList<Songs>{
var arrayList = ArrayList<Songs>()
var contentResolver = myActivity?.contentResolver
var songUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI
var songCursor = contentResolver?.query(songUri, null, null, null, null)
if(songCursor!=null && songCursor.moveToFirst()){
val songId = songCursor.getColumnIndex(MediaStore.Audio.Media._ID)
val SongTitle = songCursor.getColumnIndex((MediaStore.Audio.Media.TITLE))
val songArtist = songCursor.getColumnIndex(MediaStore.Audio.Media.ARTIST)
val songData = songCursor.getColumnIndex(MediaStore.Audio.Media.DATA)
val dateIndex = songCursor.getColumnIndex(MediaStore.Audio.Media.DATE_ADDED)
while(songCursor.moveToNext()){
var currentId = songCursor.getLong(songId)
var currentTitle = songCursor.getString(SongTitle)
var currentArtist = songCursor.getString(songArtist)
var currentData = songCursor.getString(songData)
var currentDate = songCursor.getString(dateIndex)
}
}
return arrayList
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
getSongList = getSongsFromPhone()
}
override fun onAttach(context: Context?) {
super.onAttach(context)
myActivity = context as Activity
}
override fun onAttach(activity: Activity?) {
super.onAttach(activity)
myActivity = activity
}
}// Required empty public constructor

You have
var getSongList : ArrayList<Songs>? = null
and then you say
getSongList as ArrayList<Songs>
Clearly, getSongList is null, but you insist on casting it into a not-null type ArrayList<Song>. Your hope is that it will be initialized in onCreateActivity, but apparently that callback's turn hasn't yet come at the point when your onCreateView got called.
I am sorry to hear that you are fed up with this error and hope you'll be able to provide a non-null value for your getSongList, for example by calling getSongsFromPhone().