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Implement Geojson points to map and locate me with Mapbox, in Kotlin on Android Studio

My question is about Mapbox. In this period I am working on an ANDROID application based on mapbox, using Kotlin and Fragments and my problem concerns the visualization of points on the map itself. That is my need is to be able to show points on the map through a GEOJSON file, for now I have been able to see the map in full in the application, but I cannot find a way to show the points taken from a GeoJson file and locate myself in the map via a button.
I should implement both functions in the fragment, so my problem is precisely that of not being able to show the points of a geojson file and find a way to locate myself in the map itself. I await help if there is someone able to help me with this problem, I also leave the code of the fragment class in kotlin.
Thanks everyone in advance !!
FRAGMENT HOME
class HomeFragment : Fragment() {
private var mapView: MapView? = null
#Nullable
override fun onCreateView(
inflater: LayoutInflater,
#Nullable container: ViewGroup?,
#Nullable savedInstanceState: Bundle?
): View? {
Mapbox.getInstance(
context!!.applicationContext,
"MIO CODICE MAPBOX"
)
val view: View = inflater.inflate(R.layout.fragment_home, container, false)
mapView = view.findViewById<View>(R.id.mapView) as MapView
mapView!!.onCreate(savedInstanceState)
return view
}
override fun onResume() {
super.onResume()
mapView!!.onResume()
}
override fun onPause() {
super.onPause()
mapView!!.onPause()
}
override fun onSaveInstanceState(outState: Bundle) {
super.onSaveInstanceState(outState)
mapView!!.onSaveInstanceState(outState)
}
override fun onLowMemory() {
super.onLowMemory()
mapView!!.onLowMemory()
}
override fun onDestroyView() {
super.onDestroyView()
mapView!!.onDestroy()
}
}
HOST ACTIVITY :
class HostActivity : AppCompatActivity() {
lateinit var googleSignInClient: GoogleSignInClient
private lateinit var navController: NavController
private val mAuth: FirebaseAuth = FirebaseAuth.getInstance()
private val db: FirebaseFirestore = FirebaseFirestore.getInstance()
private lateinit var drawerLayout: DrawerLayout
private lateinit var navViewBinding: DrawerHeaderLayoutBinding
override fun onCreate(savedInstanceState: Bundle?) {
setTheme(R.style.AppTheme)
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_host)
val toolbar = customToolbar
setSupportActionBar(toolbar)
val gso = GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
.requestIdToken(getString(R.string.default_web_client_id))
.requestEmail()
.build()
googleSignInClient = GoogleSignIn.getClient(this, gso)
drawerLayout = drawer_layout
navViewBinding = DrawerHeaderLayoutBinding.inflate(layoutInflater, navView, true)
val navHost =
supportFragmentManager.findFragmentById(R.id.navHostFragment) as NavHostFragment
navController = navHost.navController
val navInflater = navController.navInflater
val graph = navInflater.inflate(R.navigation.main_graph)
navController.addOnDestinationChangedListener { _, destination, _ ->
if (destination.id == R.id.onBoarding ||
destination.id == R.id.authFragment ||
destination.id == R.id.loginFragment ||
destination.id == R.id.signUpFragment
) {
toolbar.visibility = View.GONE
drawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_LOCKED_CLOSED)
} else {
toolbar.visibility = View.VISIBLE
drawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_UNLOCKED)
}
}
if (!Prefs.getInstance(this)!!.hasCompletedWalkthrough!!) {
if (mAuth.currentUser == null) {
graph.startDestination = R.id.authFragment
} else {
getUserData()
graph.startDestination = R.id.homeFragment
}
} else {
graph.startDestination = R.id.onBoarding
}
navController.graph = graph
NavigationUI.setupActionBarWithNavController(this, navController, drawerLayout)
navView.setupWithNavController(navController)
navView.setNavigationItemSelectedListener {
it.isChecked
drawerLayout.closeDrawers()
when (it.itemId) {
R.id.action_logout -> {
MyApplication.currentUser!!.active = false
FirestoreUtil.updateUser(MyApplication.currentUser!!) {
mAuth.signOut()
}
googleSignInClient.signOut()
MyApplication.currentUser = null
navController.navigate(R.id.action_logout)
}
}
true
}
}
private fun getUserData() {
val ref = db.collection("users").document(mAuth.currentUser!!.uid)
ref.get().addOnSuccessListener {
val userInfo = it.toObject(UserModel::class.java)
navViewBinding.user = userInfo
MyApplication.currentUser = userInfo
MyApplication.currentUser!!.active = true
FirestoreUtil.updateUser(MyApplication.currentUser!!) {
}
}.addOnFailureListener {
val intent = Intent(this, MyApplication::class.java)
startActivity(intent)
finish()
}
}
override fun onSupportNavigateUp(): Boolean {
return NavigationUI.navigateUp(navController, drawerLayout)
}
}

You'll need to use a GeoJsonSource. https://github.com/mapbox/mapbox-android-demo/search?q=GeoJsonSource shows how the demo app uses the source.
https://github.com/mapbox/mapbox-android-demo/blob/master/MapboxAndroidDemo/src/main/java/com/mapbox/mapboxandroiddemo/examples/basics/KotlinSupportMapFragmentActivity.kt (Its XML layout file)
Putting icons on the map. https://docs.mapbox.com/android/maps/examples/marker-symbol-layer/. Do all of the icon setup inside of the fragment's onStyleLoaded() callback as seen at https://github.com/mapbox/mapbox-android-demo/blob/master/MapboxAndroidDemo/src/main/java/com/mapbox/mapboxandroiddemo/examples/basics/KotlinSupportMapFragmentActivity.kt#L51-L55
https://github.com/mapbox/mapbox-android-demo/search?q=loadGeojson shows how the demo app loads from a GeoJson file. You could use coroutines instead of building out the AsyncTask.
Although it's in Java, https://docs.mapbox.com/android/maps/examples/show-a-users-location-on-a-fragment/ shows how to combine the Maps SDK's LocationComponent with a fragment.
Regarding moving the camera to the device's last known location when a button is clicked, see my answer at https://stackoverflow.com/a/64159178/6358488

How to notify and update list when item has been deleted using Groupie RecyclerView library and Kotlin

I have a RecyclerView implemented with the Groupie library and I can delete an item from the list fine, however need to update the view to see the change. I'd like to have something like notifyDataSetChanged() instead, so the list updates immediately. I'm a bit confused at this stage though, tried a few different ways to get an interface from the class that hosts my view holder to be triggered from the fragment that holds the adapter but I think I'm stuck now if I could get some help please.
class RecyclerProductItem(
private val activity: MainActivity,
private val product: Product, private val adapterListener: AdapterListener
) : Item<GroupieViewHolder>() {
companion object {
var clickListener: AdapterListener? = null
}
override fun bind(viewHolder: GroupieViewHolder, position: Int) {
viewHolder.apply {
with(viewHolder.itemView) {
clickListener = adapterListener
ivTrash.setOnClickListener(object : View.OnClickListener {
override fun onClick(v: View?) {
if (clickListener != null) {
Toast.makeText(context, "delete method to be added here", Toast.LENGTH_SHORT).show()
clickListener?.onClickItem(position)
}
}
})
}
}
}
override fun getLayout() = R.layout.recyclerview_item_row
interface AdapterListener {
fun onClickItem(position: Int)
}
}
Here it's my fragment. I tried to add a section to the adapter to see if it would allow me to retrieve a listener for it, but as my listener should be triggered under a specific item within the layout, this may not be the best solution, although couldn't make this work either.
class ProductsListFragment : Fragment(), RecyclerProductItem.AdapterListener {
private lateinit var adapter: GroupAdapter<GroupieViewHolder>
private val section = Section()
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_products_list, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val linearLayoutManager = LinearLayoutManager(activity)
recyclerView.layoutManager = linearLayoutManager
adapter = GroupAdapter()
adapter.add(section)
recyclerView.adapter = adapter
loadProducts()
}
private fun loadProducts() {
GetProductsAPI.postData(object : GetProductsAPI.ThisCallback {
override fun onSuccess(productList: List<JsonObject>) {
for (jo in productList) {
val gson = GsonBuilder().setPrettyPrinting().create()
val product: Product =
gson.fromJson(jo, Product::class.java)
adapter.add(
RecyclerProductItem(
activity as MainActivity,
Product(
product.id,
product.title,
product.description,
product.price
),adapterListenerToBePassedHere
)
) // This part is where I should be giving the listener, but get a red line since not sure how to get it to include it here.
}
}
})
}
companion object {
fun newInstance(): ProductsListFragment {
return ProductsListFragment()
}
}
override fun onClickItem(position: Int) {
adapter.notifyItemRemoved(position)
}
}
Many thanks.

I think you are missing this concept from the groupie Readme:
Modifying the contents of the GroupAdapter in any way automatically sends change notifications. Adding an item calls notifyItemAdded(); adding a group calls notifyItemRangeAdded(), etc.
So to remove an item, call section.remove(item). However, in your onClickItem function you currently only pass the position. Pass the item like clickListener?.onClickItem(this#RecyclerProductItem) instead.
Even more ideally and safely you should remove by product.id, e.g. clickListener?.onClickItem(this#RecyclerProductItem.product.id) then in onClickItem() you just search for the item with that product id and remove it. Let me know if I'm not clear.

Based on #carson's reply, this is what worked for me. Had to add the items to the section, the section to the adapter and then remove the item from the section based on the adapter position once that listener is clicked, passing the method that implements the listener as one of the arguments to complete the GroupAdapter.
class RecyclerProductItem(
private val activity: MainActivity,
private val product: Product, private val adapterListener: AdapterListener
) : Item<GroupieViewHolder>() {
companion object {
var clickListener: AdapterListener? = null
}
override fun bind(viewHolder: GroupieViewHolder, position: Int) {
viewHolder.apply {
with(viewHolder.itemView) {
tvTitle.text = product.title
clickListener = adapterListener
ivTrash.setOnClickListener(object : View.OnClickListener {
override fun onClick(v: View?) {
if (clickListener != null) {
Toast.makeText(context, "delete method to be added here", Toast.LENGTH_SHORT).show()
clickListener?.onClickItem(this#RecyclerProductItem.product.id, adapterPosition)
}
}
})
}
}
}
override fun getLayout() = R.layout.recyclerview_item_row
interface AdapterListener {
fun onClickItem(id: Int, position: Int)
}
}
And
private fun loadProducts() {
GetProductsAPI.postData(object : GetProductsAPI.ThisCallback,
RecyclerProductItem.AdapterListener {
override fun onSuccess(productList: List<JsonObject>) {
Log.i(LOG_TAG, "onSuccess $LOG_TAG")
for (jo in productList) {
val gson = GsonBuilder().setPrettyPrinting().create()
val product: Product =
gson.fromJson(jo, Product::class.java)
val linearLayoutManager = LinearLayoutManager(activity)
recyclerView.layoutManager = linearLayoutManager
adapter = GroupAdapter()
section.add(
RecyclerProductItem(
activity as MainActivity,
Product(
product.id,
product.title,
product.description,
product.price
), this
)
)
adapter.add(section)
recyclerView.adapter = adapter
}
}
override fun onFailure() {
Log.e(LOG_TAG, "onFailure $LOG_TAG")
}
override fun onError() {
Log.e(LOG_TAG, "onError $LOG_TAG")
}
override fun onClickItem(id: Int, position: Int) {
section.remove(adapter.getItem(position))
}
})
}

How to make Recyclerview items clickable?

I am trying to make a notes app which will allows the user make simple notes and save it. I used realm database to save the users notes. The notes are showing up fine in the recyclerview but I cannot click them.
What I want to happen is, When one of the notes in the recyclerview is clicked I want to start a new acitivty.
adapter
class NotesAdapter(private val context:Context, private val notesList: RealmResults<Notes>):RecyclerView.Adapter<RecyclerView.ViewHolder>(){
private lateinit var mOnClickListener:View.OnClickListener
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
val v = LayoutInflater.from(parent.context).inflate(R.layout.notes_rv_layout,parent,false)
v.setOnClickListener(mOnClickListener)
return ViewHolder(v)
}
override fun getItemCount(): Int {
return notesList.size
}
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
holder.itemView.titleTV.text = notesList[position]!!.title
holder.itemView.descTV.text = notesList[position]!!.description
holder.itemView.idTV.text = notesList[position]!!.id.toString()
}
private fun onClick(view:View) {
}
class ViewHolder(v: View?):RecyclerView.ViewHolder(v!!){
val title = itemView.findViewById<TextView>(R.id.titleTV)
val desc = itemView.findViewById<TextView>(R.id.descTV)
val id = itemView.findViewById<TextView>(R.id.idTV)
}
}
main activity
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
//init views
realm = Realm.getDefaultInstance()
addNotes = findViewById(R.id.addNotes)
notesRV = findViewById(R.id.NotesRV)
//onclick add notes button
addNotes.setOnClickListener {
val intent = Intent(this, AddNotesActivity::class.java)
startActivity(intent)
finish()
}
notesRV.layoutManager = StaggeredGridLayoutManager(2,LinearLayoutManager.VERTICAL)
getAllNotes()
}
private fun getAllNotes() {
notesList = ArrayList()
val results:RealmResults<Notes> = realm.where<Notes>(Notes::class.java).findAll()
notesRV.adapter = NotesAdapter(this, results)
notesRV.adapter!!.notifyDataSetChanged()
}
}

use onBindViewHolder for that:
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
holder.itemView.titleTV.text = notesList[position]!!.title
holder.itemView.descTV.text = notesList[position]!!.description
holder.itemView.idTV.text = notesList[position]!!.id.toString()
holder.itemView.setOnClickListener{
val intent = Intent(holder.itemView.context,YourActivity::class.java)
holder.itemView.context.startActivity(intent)
}
}

How can I maintain scroll position in a fragment?

I am trying to save the scroll position in a fragment. Flow->
Fragment A - scrolled to some position
Fragment B
Come back to Fragment A to the same position and not create everything from the top.
My attempts
Attempt 1
private var index: Int = -1
private var top = -1
private var lastFirstVisiblePosition : Int? = null
override fun onPause() {
super.onPause()
index = linearLayoutManager.findFirstVisibleItemPosition()
val v: View = homeRecyclerView!!.getChildAt(0)
top = v.top - homeRecyclerView!!.paddingTop
val preferences = PreferenceManager.getDefaultSharedPreferences(context)
preferences.edit()
.putInt("position", index)
.putInt("offset", top)
.apply();
}
override fun onResume() {
super.onResume()
val preferences = PreferenceManager.getDefaultSharedPreferences(context)
index = preferences.getInt("position",0)
top = preferences.getInt("offset",0)
if(this.index != -1)
{
(homeRecyclerView!!.layoutManager as LinearLayoutManager)
.scrollToPositionWithOffset(index,top)
}
}
Outcome: Doesn't scroll. Code reaches the line (homeRecyclerView!!.layoutManager as LinearLayoutManager).scrollToPositionWithOffset(index,top) but doesn't scroll
Attempt 2
private val BUNDLE_RECYCLER_LAYOUT = "classname.recycler.layout"
override fun onViewStateRestored(savedInstanceState: Bundle?) {
super.onViewStateRestored(savedInstanceState)
if (savedInstanceState != null)
{
val savedRecyclerLayoutState: Parcelable? =
savedInstanceState.getParcelable(BUNDLE_RECYCLER_LAYOUT)
homeRecyclerView!!.layoutManager!!.onRestoreInstanceState(savedRecyclerLayoutState)
}
}
override fun onSaveInstanceState(outState: Bundle) {
super.onSaveInstanceState(outState)
outState.putParcelable(BUNDLE_RECYCLER_LAYOUT, homeRecyclerView!!.layoutManager!!.onSaveInstanceState());
}
Outcome: No error but doesn't scroll
Attempt 3
override fun onPause() {
super.onPause()
state = linearLayoutManager.onSaveInstanceState()
}
I know something about Parcelable but I don't know how to implement it
My HomeFragment:
class HomeFragment : Fragment() {
private var homePostAdapter: HomePostAdapter? = null
private var postList: MutableList<HomePostModel>? = null
val linearLayoutManager = LinearLayoutManager(context)
var homeRecyclerView: RecyclerView? = null
private var userFollowingList: MutableList<HomePostModel>? = null
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
val view = inflater.inflate(R.layout.fragment_home, container, false)
homeRecyclerView = view.findViewById<RecyclerView>(R.id.recycler_view_home)
linearLayoutManager.reverseLayout = true
linearLayoutManager.stackFromEnd = true
homeRecyclerView!!.layoutManager = linearLayoutManager
postList = ArrayList()
homePostAdapter =
context?.let { HomePostAdapter(it, postList as ArrayList<HomePostModel>, true) }
homeRecyclerView!!.adapter = homePostAdapter
homeRecyclerView!!.setHasFixedSize(true)
homeRecyclerView!!.setItemViewCacheSize(20)
return view
}
On returning to this fragment, I want to get the scroll position the user was on. Right now, it loads from the top. My attempts have no error hence I don't understand what's wrong. Thank you for the help.
UPDATE
The issue was that I had not given a small delay using Holder().postDelayed. It's working fine now.
However, could someone kindly tell me the correct way to retrieve the exact position of the scroll? Right now my attempt 1 is working but the scroll is jumpy and not exact.
UPDATE 2
I found the dy position and using it scroll to last state. See answer. If anyone has a better approach, kindly let me know.

In the onCreateView I have found the dy and based on that I am finding the scroll position. Since dy is only available in the smoothScroll, I use that on onResume to get back to the position.
Inside the fragment/Activity:
homeRecyclerView!!.addOnScrollListener(object : RecyclerView.OnScrollListener() {
override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
super.onScrolled(recyclerView, dx, dy)
scrolled += dy
val preferences = PreferenceManager.getDefaultSharedPreferences(context)
preferences.edit()
.putInt("position", scrolled)
.apply()
}
})
OnResume:
override fun onResume() {
super.onResume()
val preferences = PreferenceManager.getDefaultSharedPreferences(context)
val index = preferences.getInt("position", 0)
homeRecyclerView!!.smoothScrollBy(0, index)
}, 50)
}

Fragments memory leaks

I have only one activity and all navigation is solved through fragments. If I open the fragment and come back, the fragment will be still in memory and memory will be growing.
What am I doing wrong? Do I have to manually remove listeners? In the onDestroy method, getView is already null.
How I add fragments:
fun replaceFragment(
fragmentManager: FragmentManager?,
fragment: Fragment?,
frameId: Int,
tag: String?
) {
if (fragmentManager != null && fragment != null) {
val previousFragment = fragmentManager.findFragmentById(frameId)
if (fragment != previousFragment) {
val transaction = fragmentManager.beginTransaction()
transaction.replace(frameId, fragment, tag)
transaction.addToBackStack(tag)
transaction.commitAllowingStateLoss()
}
}
}
Fragment close by the back button:
EDIT:
How I create Fragment
companion object {
fun create(number: Long): ManageUnitFragment {
val fragment = ManageUnitFragment()
val params = Bundle()
params.putLong(Keys.Number, number)
fragment.arguments = params
return fragment
}
}
How I set Listeners (on buttons)
import kotlinx.android.synthetic.main.myFragment.*
vMyButton.setOnClickListener {
myAction()
}
EDIT
If I remove this line vButtonClose.setOnClickListener... , the ManageUnitFragments will no longer be in the heap dump.
ManageUnitFragment:
import kotlinx.android.synthetic.main.fragment_manage_unit.*
class ManageUnitFragment : Fragment() {
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_manage_unit, container, false)
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
vButtonClose.setOnClickListener {
activity?.onBackPressed()
}
}
companion object {
fun create(unitNumber: Long, wagonWagonUnit: WagonUnit): ManageUnitFragment {
val fragment = ManageUnitFragment()
return fragment
}
}
}

Have you tried to add 'many' fragments? Do you actually get OutOfMemoryException?
Maybe they just remain in memory until more of it is needed. Then they will be garbage collected.