Develop Reference

Can I press a button in Activity A to filter a RecyclerView in Activity B?

What I want to reach is that the same RecyclerView shows different data depending on which button the App user pressed before in the MainActivity.kt.
In my MainActivity.kt I have two buttons, which both send the user to the same RecyclerView Activity (RecyclerViewLayout.kt) via Intent.
Example: The RecyclerView contains a picture of an apple and a banana. By pressing button A in MainActivity.kt, the RecyclerView in RecyclerViewLayout.kt should only show the apple. By pressing button B it should only show the banana. In my real app there are no fruits. but Tutorials, which should be filtered like described.
I gently ask for help here how to do that. Maybe there is also a better way to reach my target to filter the RecyclerView?
Thanks in Advance!
MainActivity.kt
class MainActivity : AppCompatActivity() {
private var binding:ActivityMainBinding? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding?.root)
val buttonRecyclerView = findViewById<Button>(R.id.btn_recyclerview)
buttonRecyclerView.setOnClickListener {
val intent = Intent(this, RecyclerViewLayout::class.java)
startActivity(intent)
}
}}
RecyclerViewLayout.kt
class RecyclerViewLayout : AppCompatActivity() {
private lateinit var newRecylerview : RecyclerView
private lateinit var newArrayList : ArrayList<RecyclerViewDataClass>
private lateinit var tempArrayList : ArrayList<RecyclerViewDataClass>
lateinit var imageId : Array<Int>
lateinit var tutorialHeading : Array<String>
lateinit var tutorialText : Array<String>
lateinit var url : Array<String>
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_recycler_view_layout)
imageId = arrayOf(
R.drawable.brake,
R.drawable.brake,
)
tutorialHeading = arrayOf(
getString(R.string.scheibenbremse_lüften_heading),
getString(R.string.felgenbremse_richten_heading),
)
tutorialText = arrayOf(
getString(R.string.scheibenbremse_lüften_text),
getString(R.string.felgenbremse_richten_text),
)
url = arrayOf(
getString(R.string.url_a),
getString(R.string.url_b),
)
newRecylerview =findViewById(R.id.recyclerView)
newRecylerview.layoutManager = LinearLayoutManager(this)
newRecylerview.setHasFixedSize(true)
newArrayList = arrayListOf<RecyclerViewDataClass>()
tempArrayList = arrayListOf<RecyclerViewDataClass>()
getUserdata()
}
override fun onCreateOptionsMenu(menu: Menu?): Boolean {
menuInflater.inflate(R.menu.menu_item,menu)
val item = menu?.findItem(R.id.search_action)
val searchView = item?.actionView as SearchView
searchView.setOnQueryTextListener(object : SearchView.OnQueryTextListener{
override fun onQueryTextSubmit(query: String?): Boolean {
TODO("Not yet implemented")
}
override fun onQueryTextChange(newText: String?): Boolean {
tempArrayList.clear()
val searchText = newText!!.toLowerCase(Locale.getDefault())
if (searchText.isNotEmpty()){
newArrayList.forEach {
if (it.heading.toLowerCase(Locale.getDefault()).contains(searchText)){
tempArrayList.add(it)
}
}
newRecylerview.adapter!!.notifyDataSetChanged()
}else{
tempArrayList.clear()
tempArrayList.addAll(newArrayList)
newRecylerview.adapter!!.notifyDataSetChanged()
}
return false
}
})
return super.onCreateOptionsMenu(menu)
}
private fun getUserdata() {
for(i in imageId.indices){
val news = RecyclerViewDataClass(imageId[i],tutorialHeading[i],url[i])
newArrayList.add(news)
}
tempArrayList.addAll(newArrayList)
val adapter = RecyclerViewAdapter(tempArrayList)
newRecylerview.adapter = adapter
adapter.setOnItemClickListener(object : RecyclerViewAdapter.onItemClickListener{
override fun onItemClick(position: Int) {
val intent = Intent(this#RecyclerViewLayout,TutorialsActivity::class.java)
intent.putExtra("tutorialHeading",newArrayList[position].heading)
intent.putExtra("imageId",newArrayList[position].titleImage)
intent.putExtra("url",newArrayList[position].url)
intent.putExtra("tutorialText",tutorialText[position])
startActivity(intent)
}
})
}}
RecyclerViewAdapter.kt
class RecyclerViewAdapter(private val newsList : ArrayList<RecyclerViewDataClass>) : RecyclerView.Adapter<RecyclerViewAdapter.MyViewHolder>(),
Filterable {
private lateinit var mListener : onItemClickListener
interface onItemClickListener{
fun onItemClick(position : Int)
}
fun setOnItemClickListener(listener: onItemClickListener){
mListener = listener
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
val itemView = LayoutInflater.from(parent.context).inflate(R.layout.list_item,
parent,false)
return MyViewHolder(itemView,mListener)
}
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
val currentItem = newsList[position]
holder.titleImage.setImageResource(currentItem.titleImage)
holder.tvHeading.text = currentItem.heading
}
override fun getItemCount(): Int {
return newsList.size
}
class MyViewHolder(itemView : View, listener: onItemClickListener) : RecyclerView.ViewHolder(itemView){
val titleImage : ShapeableImageView = itemView.findViewById(R.id.title_image)
val tvHeading : TextView = itemView.findViewById(R.id.tvHeading)
init {
itemView.setOnClickListener {
listener.onItemClick(adapterPosition)
}
}
}
override fun getFilter(): Filter {
TODO("Not yet implemented")
}}
RecyclerViewDataClass.kt
data class RecyclerViewDataClass(var titleImage: Int, var heading: String, val url: String)
**Tutorials Activity**
class TutorialsActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_tutorials)
val headingNews : TextView = findViewById(R.id.heading)
val mainNews : TextView = findViewById(R.id.news)
val imageNews : ImageView = findViewById(R.id.image_heading)
val bundle : Bundle?= intent.extras
val tutorialHeading = bundle!!.getString("tutorialHeading")
val imageId = bundle.getInt("imageId")
val tutorialText = bundle.getString("tutorialText")
val url = bundle.getString("url")
headingNews.text = tutorialHeading
mainNews.text = tutorialText
imageNews.setImageResource(imageId)
imageNews.setOnClickListener {
val openURL = Intent(Intent.ACTION_VIEW)
openURL.data = Uri.parse(url.toString())
startActivity(openURL)
}
}}

I believe you can pass data about which button is clicked using intents. Here's a link about that:
How to Pass custom object via intent in kotlin
For example, you can pass "A" if button A is clicked and "B" if button B is clicked, and then get that string in RecyclerViewLayout.kt to determine which elements should be shown.

According to me the simplest solution for doing this is you should have a boolean in preferences you can set preferences according to the button clicked and set data in your adapter to by getting the preferences value.
If you want to set data according to the button clicked
Other way is to pass the action onClick while starting a new Activity and getAction() in your second Activity.
This way you can also set data of your recyclerView by passing different data

Is there a way of passing the NDEF message to a string?

so I have an NFC tag that stores a URL and I am building an android app that reads that tag and starts the app to the Main activity. After that I have a WebView that displays that website. My problem here is, each tag has a different url/path (lets say they are clothing items and each point to a product on the website). How do I get the NDEF message from the tag (the url) and pass it to that parameter of the webview? Thank your for your help, here I will leave my code.
I have followed the android documentation on NFC both, basic and advanced, googled every page and searched everything on reddit, however I could not find any answer...
This is my Main Activity, the one that opens as soon as it reads the tag:
class MainActivity : AppCompatActivity() {
private var adapter: NfcAdapter? = null
// Pending intent for NFC intent foreground dispatch.
// Used to read all NDEF tags while the app is running in the foreground.
private var nfcPendingIntent: PendingIntent? = null
// Optional: filter NDEF tags this app receives through the pending intent.
//private var nfcIntentFilters: Array<IntentFilter>? = null
private val KEY_LOG_TEXT = "logText"
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
initNfcAdapter()
if (intent != null)
{
processIntent(intent)
}
}
private fun initNfcAdapter() {
val nfcManager = getSystemService(Context.NFC_SERVICE) as NfcManager
adapter = nfcManager.defaultAdapter
}
override fun onResume() {
super.onResume()
enableNfcForegroundDispatch()
}
private fun enableNfcForegroundDispatch() {
try {
val intent = Intent(this, javaClass).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP)
val nfcPendingIntent = PendingIntent.getActivity(this, 0, intent, 0)
adapter?.enableForegroundDispatch(this, nfcPendingIntent, null, null)
} catch (ex: IllegalStateException) {
}
}
override fun onPause() {
disableNfcForegroundDispatch()
super.onPause()
}
private fun disableNfcForegroundDispatch() {
try {
adapter?.disableForegroundDispatch(this)
} catch (ex: IllegalStateException) {
}
}
private fun processIntent(checkIntent: Intent) {
if(checkIntent.action == NfcAdapter.ACTION_NDEF_DISCOVERED) {
val rawMessages = checkIntent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES)
}
}
}
This is the webview activity:
class Webview : AppCompatActivity() {
private lateinit var webview: Webview1
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_webview)
val myWebView: WebView = findViewById(R.id.webview)
myWebView.webViewClient = object : WebViewClient () {
override fun shouldOverrideUrlLoading(view: WebView?, url: String?): Boolean {
if (url != null) {
view?.loadUrl(url)
}
return true
}
}
myWebView.loadUrl("https://website.com")
myWebView.settings.javaScriptEnabled=true
myWebView.settings.allowContentAccess=true
myWebView.settings.domStorageEnabled=true
myWebView.settings.useWideViewPort=true
myWebView.settings.setAppCacheEnabled(true)
}
}
I want to pass the NDEF message to myWebVIew.loadUrl().

Android Coroutines block UI click listener

I'm using MVVM as architecture, also the repository pattern. I have a Web service, a room database also. Using coroutines block any button I click.
There's a list/detail implemented with a fragment and an activity respectively.
I can figure out what's wrong in the way I implemented the coroutines and Viewmodel.
class BuySharedViewModel(application: Application) : AndroidViewModel(application) {
private val repository: BuyRepository
var allBuys: LiveData<List<Buy>>
init {
val buyDao = KunukRoomDatabase.getDatabase(application, viewModelScope).buyDao()
val buyRemote = BuyRemote()
repository = BuyRepository.getInstance(buyDao , buyRemote)
//Use async because it return a result
viewModelScope.launch { getAllBuys() }
allBuys = buyDao.loadAllBuys()
}
private suspend fun getAllBuys() {
repository.getBuys()
}
}
Here's is the Repository, it take data from web service and add it to the room database, while ViewModel get's data from room database.
class BuyRepository (private val buyDao: BuyDao, private val buyRemote: BuyRemote) {
private val job = SupervisorJob()
private val scope = CoroutineScope(Dispatchers.Default + job)
companion object {
//For singleton instantiation
#Volatile private var instance: BuyRepository? = null
fun getInstance(buyDao: BuyDao, buyRemote: BuyRemote) =
instance ?: synchronized(this) {
instance ?: BuyRepository(buyDao, buyRemote)
.also { instance = it}
}
}
suspend fun getBuys(){
refresh()
}
private suspend fun refresh(){
try {
val list = scope.async { buyRemote.loadBuys() }
list.await().forEach { buy -> insert(buy) }
} catch (e: Throwable) {}
}
#WorkerThread
private fun insert(buy: Buy) {
buyDao.insertBuy(buy)
}
}
The fragment work, data are displayed, when i click on an item from that fragment(recyclerView) it work, the activity display details data. But none of the click on that activity works, like it doesn't detect the clicks. I guess it got something to do with the coroutines because when I comment out the code viewmodelScope.launch { getAllBuys()} from the BuySharedViewModel it works, because it load data from the previous call from room database, and the clicks works.
Here's the code in the detail view:
class BuyDetailActivity : AppCompatActivity() {
private lateinit var sharedViewModel: BuySharedViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
lateinit var buy: Buy
sharedViewModel = ViewModelProviders.of(this).get(BuySharedViewModel::class.java)
val position = intent.getIntExtra("position", 0)
sharedViewModel.allBuys.observe(this, Observer<List<Buy>> { buys ->
buy = buys[position]
val binding: com.example.drake.kunuk.databinding.ActivityBuyDetailBinding =
DataBindingUtil.setContentView(this, com.example.drake.kunuk.R.layout.activity_buy_detail)
binding.buy = buy
val agentNumber = buy.agentNumber?:"+50937438713"
bnvContactAgent.setOnNavigationItemSelectedListener { item ->
when (item.itemId) {
com.example.drake.kunuk.R.id.action_call -> {
val callNumberUri = Uri.parse("tel:$agentNumber")
val callIntent = Intent(Intent.ACTION_DIAL, callNumberUri)
startActivity(callIntent)
}
com.example.drake.kunuk.R.id.action_sms -> {
val smsNumberUri = Uri.parse("sms:$agentNumber")
val smsIntent = Intent(Intent.ACTION_SENDTO, smsNumberUri)
startActivity(smsIntent)
}
com.example.drake.kunuk.R.id.action_email -> {
val uriText = "mailto:drakecolin#gmail.com" +
"?subject=" + Uri.encode("I'm interested in $agentNumber") +
"&body=" + Uri.encode("Hello, ")
val uri = Uri.parse(uriText)
val sendIntent = Intent(Intent.ACTION_SENDTO)
sendIntent.data = uri
startActivity(Intent.createChooser(sendIntent, "Send email"))
}
}
false
}
This is the code of my fragment:
class BuyFragment : Fragment() {
companion object {
fun newInstance() = BuyFragment()
}
private lateinit var viewModel: BuySharedViewModel
private val buyList = ArrayList<Buy>()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
// Get a new or existing ViewModel from the ViewModelProvider.
viewModel = ViewModelProviders.of(this).get(BuySharedViewModel::class.java)
// Add an observer on the LiveData returned by loadAllBuys.
// The onChanged() method fires when the observed data changes and the activity is
// in the foreground.
viewModel.allBuys.observe(this, Observer<List<Buy>> { buys ->
// Update the cached copy of the words in the adapter.
buys?.let { (rvBuy.adapter as BuyAdapter).setBuys(it) }
progressBar.visibility = View.GONE
})
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.buy_fragment, container, false)
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
rvBuy.layoutManager = LinearLayoutManager(context)
rvBuy.adapter = BuyAdapter(activity!!.applicationContext,
R.layout.buy_card, buyList)
progressBar.visibility = View.VISIBLE
}
}
This is the code for the BuyDao:
#Dao
interface BuyDao {
#Insert(onConflict = OnConflictStrategy.REPLACE)
fun insertBuy(vararg buys: Buy)
#Update
fun updateBuy(vararg buys: Buy)
#Delete
fun deleteBuys(vararg buys: Buy)
#Query("SELECT * FROM buys")
fun loadAllBuys(): LiveData<List<Buy>>
#Query("DELETE FROM buys")
suspend fun deleteAll()
}

viewModelScope by default uses Dispatchers.Main and it is blocking your UI.
Try this:
viewmodelScope.launch(Dispatchers.IO) { getAllBuys()}
Edit:
The problem is your setting listner on BottomNavigation when your livedata is updated which is causing this weird issue.
Replace your BuyDetailActivity code with this:
class BuyDetailActivity : AppCompatActivity() {
private lateinit var sharedViewModel: BuySharedViewModel
private var agentNumber = ""
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
val binding: ActivityBuyDetailBinding =
DataBindingUtil.setContentView(this, R.layout.activity_buy_detail)
binding.buy = Buy()
lateinit var buy: Buy
sharedViewModel = ViewModelProviders.of(this).get(BuySharedViewModel::class.java)
val position = intent.getIntExtra("position", 0)
sharedViewModel.allBuys.observe(this, Observer<List<Buy>> { buys ->
buy = buys[position]
binding.buy = buy
binding.executePendingBindings()
agentNumber = buy.agentNumber
// set animation duration via code, but preferable in your layout files by using the animation_duration attribute
expandableTextView.setAnimationDuration(750L)
// set interpolators for both expanding and collapsing animations
expandableTextView.setInterpolator(OvershootInterpolator())
// or set them separately.
expandableTextView.expandInterpolator = OvershootInterpolator()
expandableTextView.collapseInterpolator = OvershootInterpolator()
// toggle the ExpandableTextView
buttonToggle.setOnClickListener {
buttonToggle.setText(if (expandableTextView.isExpanded) com.example.drake.kunuk.R.string.more else com.example.drake.kunuk.R.string.less)
expandableTextView.toggle()
}
// but, you can also do the checks yourself
buttonToggle.setOnClickListener {
if (expandableTextView.isExpanded) {
expandableTextView.collapse()
buttonToggle.setText(com.example.drake.kunuk.R.string.more)
} else {
expandableTextView.expand()
buttonToggle.setText(com.example.drake.kunuk.R.string.less)
}
}
//Open photoView activity when clicked
ivHouseDetail.setOnClickListener {
applicationContext
.startActivity(
Intent(
applicationContext,
ViewPagerActivity::class.java
)
.putExtra("imageList", buy.propertyImage)
.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
)
}
})
findViewById<BottomNavigationView>(R.id.bnvContactAgent)?.setOnNavigationItemSelectedListener { item ->
when (item.itemId) {
R.id.action_call -> {
Log.e("BIRJU", "Action call")
val callNumberUri = Uri.parse("tel:$agentNumber")
val callIntent = Intent(Intent.ACTION_DIAL, callNumberUri)
startActivity(callIntent)
}
R.id.action_sms -> {
Log.e("BIRJU", "Action SMS")
val smsNumberUri = Uri.parse("sms:$agentNumber")
val smsIntent = Intent(Intent.ACTION_SENDTO, smsNumberUri)
startActivity(smsIntent)
}
R.id.action_email -> {
Log.e("BIRJU", "Action Email")
val uriText = "mailto:drakecolin#gmail.com" +
"?subject=" + Uri.encode("I'm interested in $agentNumber") +
"&body=" + Uri.encode("Hello, ")
val uri = Uri.parse(uriText)
val sendIntent = Intent(Intent.ACTION_SENDTO)
sendIntent.data = uri
startActivity(Intent.createChooser(sendIntent, "Send email"))
}
}
false
}
}
}

View list of bluetooth devices in Kotlin?

I have a small bluetooth project in kotlin. The code for it is below:
var mArrayAdapter: ArrayAdapter<String>? = null
val bluetoothAdapter: BluetoothAdapter = BluetoothAdapter.getDefaultAdapter()
var myList: MutableList<String> = mutableListOf<String>()
var devices = ArrayList<BluetoothDevice>()
var devicesMap = HashMap<String, BluetoothDevice>()
class MainActivity : AppCompatActivity(), View.OnClickListener {
private val REQUEST_ENABLE_BT = 1000
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
findViewById<View>(R.id.btn_scan).setOnClickListener(this)
checkBluetoothStatus()
val filter = IntentFilter(BluetoothDevice.ACTION_FOUND)
registerReceiver(receiver, filter)
mArrayAdapter = ArrayAdapter(this, R.layout.dialog_select_device)
}
private val receiver = object : BroadcastReceiver() {
override fun onReceive(context: Context, intent: Intent) {
val action: String? = intent.action
when(action) {
BluetoothDevice.ACTION_FOUND -> {
val device: BluetoothDevice =
intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE)
val deviceName = device.name
myList.add(deviceName)
}
}
}
}
override fun onClick(v: View?) {
when (v?.id) {
R.id.btn_scan ->
startScan()
}
}
fun startScan() {
if (BluetoothAdapter.getDefaultAdapter().startDiscovery()) {
val myToast = Toast.makeText(this, myList.toString(), Toast.LENGTH_SHORT)
myToast.show()
}
}
}
When a user clicks a button, I want to be able to see a list of other bluetooth devices (which I thought the onReceive method would enable me to do). So I'm adding device names to the myList variable, which I'm then displaying in a toast. But at the moment when they click, nothing comes up. Grateful for your advice.

Flutter method channel & Facebook AppEventLogger

I am trying to call a function from flutter on onTap event and pass some arguments into native android. Please note that I am more of a PHP/JavaScript developer, I am Kotlin virgin.
So far I have managed to do this using:
static const platform = const MethodChannel('foo.bar/example');
void _onTap() {
var arguments = {'name': widget.recipe.name, 'id': widget.recipe.id.toString()};
platform.invokeMethod('setPageView', arguments);
}
Then in the MainActivity.kt
class MainActivity : FlutterActivity() {
private val channel: String = "foo.bar/example"
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
GeneratedPluginRegistrant.registerWith(this)
val logger = AppEventsLogger.newLogger(this)
MethodChannel(flutterView, channel).setMethodCallHandler(MethodChannel.MethodCallHandler(fun(methodCall: MethodCall, result: MethodChannel.Result) {
if (methodCall.method.equals("setPageView")) {
val params = Bundle()
params.putString(AppEventsConstants.EVENT_PARAM_CONTENT_TYPE, "recipe")
params.putString(AppEventsConstants.EVENT_PARAM_CONTENT, methodCall.argument("recipe"))
params.putString(AppEventsConstants.EVENT_PARAM_CONTENT_ID, methodCall.argument("id"))
logger.logEvent(AppEventsConstants.EVENT_NAME_VIEWED_CONTENT, 0.0, params)
logger.logEvent("pageView", 0.0, params)
System.out.println("Called setPageView.")
}
}))
}
}
The problem is that when I log inside the MethodCallHandler the event is not sent to facebook for some reason. But if I log something right below the
val logger = AppEventsLogger.newLogger(this)
The event is successfully sent to facebook.
The code inside the MethodCallHandler executes, so that´s not the problem.
Any idea what I did wrong?
Thank You

Solved by making the content of MethodCallHandler as a standalone method in the MainActivity class
class MainActivity : FlutterActivity() {
private val channel: String = "foo.bar/example"
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
GeneratedPluginRegistrant.registerWith(this)
MethodChannel(flutterView, channel).setMethodCallHandler(
MethodChannel.MethodCallHandler(
fun(methodCall: MethodCall, result: MethodChannel.Result) {
if (methodCall.method.equals("setPageView")) {
logPageView(methodCall.argument("name"), methodCall.argument("id"))
}
}
)
)
}
fun logPageView(name: String?, id: String?) {
val logger = AppEventsLogger.newLogger(this)
val params = Bundle()
params.putString(AppEventsConstants.EVENT_PARAM_CONTENT_TYPE, "recipe")
params.putString(AppEventsConstants.EVENT_PARAM_CONTENT, name)
params.putString(AppEventsConstants.EVENT_PARAM_CONTENT_ID, id)
params.putString(AppEventsConstants.EVENT_PARAM_CURRENCY, "EUR")
logger.logEvent(AppEventsConstants.EVENT_NAME_VIEWED_CONTENT, 0.0, params)
}
}