I have an activity which displays reservation list
The reservation list is stored in SQLite, which works OK
override fun onCreate(savedInstanceState: Bundle?) {
var reservationList = arrayListOf<ReservationModel>()
reservationList.addAll(reservationDB!!.reservationDao().getReservationList())
reservationAdapter = reservationListAdapter(reservationList, this#ReservationListActivity)
val llm01 = LinearLayoutManager(applicationContext, LinearLayoutManager.VERTICAL, true)
reservation_recview.layoutManager = llm01
reservation_recview.adapter = reservationAdapter
}
Then I want to remove "Zenbu City". This is the code:
reservationDB.reservationDao().deleteReservation(selectedReservation)
val newReservationList = arrayListOf<ReservationModel>()
newReservationList.addAll(reservationDB.reservationDao().getAllReservations())
reservationAdapter.removeItemAndRefresh(selectedReservation, newReservationList)
This is how removeItemAndRefresh() implemented in ReservationAdapter:
fun removeItemAndRefresh(selectedItem: ReservationModel, newList: ArrayList<ReservationModel>){
theList.remove(selectedItem)
theList.clear()
theList.addAll(newList)
notifyDataSetChanged()
}
The result is this:
See a noticable gap/empty space on the RecyclerView? How to fix that?
Related
I have a basic function that displays the elapsed time every time the button is pressed. I cannot get the logic in MainActivity to transfer to the recyclerview adapter. I simply want the text output color to change to red after the time passes 5 seconds. I have tried to research how to do this for the past week and I cannot find the exact answer. I'm hoping someone can help.
I have tried it with and without the boolean in the data class. I wasn't sure if that was required.
Here is my code:
Main Activity:`
class MainActivity : AppCompatActivity() {
var startTime = SystemClock.elapsedRealtime()
var displaySeconds = 0
private lateinit var binding: ActivityMainBinding
private val secondsList = generateSecondsList()
private val secondsAdapter = Adapter(secondsList)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
recyclerView.adapter = secondsAdapter
recyclerView.layoutManager = LinearLayoutManager(this)
recyclerView.setHasFixedSize(false)
binding.button.setOnClickListener {
getDuration()
addSecondsToRecyclerView()
}
}
fun getDuration(): Int {
val endTime = SystemClock.elapsedRealtime()
val elapsedMilliSeconds: Long = endTime - startTime
val elapsedSeconds = elapsedMilliSeconds / 1000.0
displaySeconds = elapsedSeconds.toInt()
return displaySeconds
}
private fun generateSecondsList(): ArrayList<Seconds> {
return ArrayList()
}
fun addSecondsToRecyclerView() {
val addSeconds =
Seconds(getDuration(), true)
secondsList.add(addSeconds)
secondsAdapter.notifyItemInserted(secondsList.size - 1)
}
}
Adapter:
var adapterSeconds = MainActivity().getDuration()
class Adapter(
private val rvDisplay: MutableList<Seconds>
) : RecyclerView.Adapter<Adapter.AdapterViewHolder>() {
class AdapterViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
val textView1: TextView = itemView.tv_seconds
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): AdapterViewHolder {
val myItemView = LayoutInflater.from(parent.context).inflate(
R.layout.rv_item,
parent, false
)
return AdapterViewHolder(myItemView)
}
override fun onBindViewHolder(holder: Adapter.AdapterViewHolder, position: Int) {
val currentDisplay = rvDisplay[position]
currentDisplay.isRed = adapterSeconds > 5
holder.itemView.apply {
val redColor = ContextCompat.getColor(context, R.color.red).toString()
val blackColor = ContextCompat.getColor(context, R.color.black).toString()
if (currentDisplay.isRed) {
holder.textView1.setTextColor(redColor.toInt())
holder.textView1.text = currentDisplay.rvSeconds.toString()
} else {
holder.textView1.setTextColor(blackColor.toInt())
holder.textView1.text = currentDisplay.rvSeconds.toString()
}
}
}
override fun getItemCount() = rvDisplay.size
}
Data Class:
data class Seconds(
var rvSeconds: Int,
var isRed: Boolean
)
when you call secondsList.add(addSeconds) then the data that is already inside secondsList should be updated too.
you could do something like
private var secondsList = generateSecondsList() // make this var
fun addSecondsToRecyclerView() {
val addSeconds =
Seconds(getDuration(), true)
secondsList.add(addSeconds)
if ( /* TODO check if time has passed */) {
secondsList = secondsList.map { it.isRed = true }
secondsAdapter.rvDisplay = secondsList // TODO also make rvDisplay a var
secondsAdapter.notifyDatasetChanged() // also need to tell rv to redraw the all views
} else {
secondsAdapter.notifyItemInserted(secondsList.size - 1)
}
}
that might work, but to be honest it looks bad... There is already a lot of logic inside Activity. Read about MVVM architecture and LiveData, there should be another class called ViewModel that would keep track of time and the data. Activity should be as simple as possible, because it has lifecycle, so if you rotate the screen, all your state will be lost.
Your code isn't really working because of this:
var adapterSeconds = MainActivity().getDuration()
override fun onBindViewHolder(holder: Adapter.AdapterViewHolder, position: Int) {
...
currentDisplay.isRed = adapterSeconds > 5
...
}
You're only setting adapterSeconds right there, so it never updates as time passes. I assume you want to know the moment 5 seconds has elapsed, and then update the RecyclerView at that moment - in that case you'll need some kind of timer task that will fire after 5 seconds, and can tell the adapter to display things as red. Let's deal with that first:
class Adapter( private val rvDisplay: MutableList ) : RecyclerView.Adapter<Adapter.AdapterViewHolder>() {
private var displayRed = false
set(value) {
field = value
// Refresh the display - the ItemChanged methods mean something about the items
// has changed, rather than a structural change in the list
// But you can use notifyDataSetChanged if you want (better to be specific though)
notifyItemRangeChanged(0, itemCount)
}
override fun onBindViewHolder(holder: Adapter.AdapterViewHolder, position: Int) {
if (displayRed) {
// show things as red - you shouldn't need to store that state in the items
// themselves, it's not about them - it's an overall display state, right?
} else {
// display as not red
}
}
So with that setter function, every time you update displayRed it'll refresh the display, which calls onBindViewHolder, which checks displayRed to see how to style things. It's better to put all this internal refreshing stuff inside the adapter - just pass it data and events, let it worry about what needs to happen internally and to the RecyclerView it's managing, y'know?
Now we have a thing we can set to control how the list looks, you just need a timer to change it. Lots of ways to do this - a CountdownTimer, a coroutine, but let's keep things simple for this example and just post a task to the thread's Looper. We can do that through any View instead of creating a Handler:
// in MainActivity
recyclerView.postDelayed({ secondsAdapter.displayRed = true }, 5000)
That's it! Using any view, post a delayed function that tells the adapter to display as red.
It might be more helpful to store that runnable as an object:
private val showRedTask = Runnable { secondsAdapter.displayRed = true }
...
recyclerView.postDelayed(showRedTask, 5000)
because then you can easily cancel it
recyclerView.removeCallbacks(showRedTask)
Hopefully that's enough for you to put some logic together to get what you want. Set displayRed = false to reset the styling, use removeCallbacks to cancel any running task, and postDelayed to start a new countdown. Not the only way to do it, but it's pretty neat!
I finally figured it out using a companion object in Main Activity with a boolean set to false. If the time exceeded 5 seconds, then it set to true.
The adapter was able to recognize the companion object and change the color of seconds to red if they exceeded 5.
I use MVVM and have a list of data elements in a database that is mapped through a DAO and repository to ViewModel functions.
Now, my problem is rather banal; I just want to use the data in fragment variables, but I get a type mismatch.
The MVVM introduces a bit of code, and for completeness of context I'll run through it, but I'll strip it to the essentials:
The data elements are of a data class, "Objects":
#Entity(tableName = "objects")
data class Objects(
#ColumnInfo(name = "object_name")
var objectName: String
) {
#PrimaryKey(autoGenerate = true)
var id: Int? = null
}
In ObjectsDao.kt:
#Dao
interface ObjectsDao {
#Query("SELECT * FROM objects")
fun getObjects(): LiveData<List<Objects>>
}
My database:
#Database(
entities = [Objects::class],
version = 1
)
abstract class ObjectsDatabase: RoomDatabase() {
abstract fun getObjectsDao(): ObjectsDao
companion object {
// create database
}
}
In ObjectsRepository.kt:
class ObjectsRepository (private val db: ObjectsDatabase) {
fun getObjects() = db.getObjectsDao().getObjects()
}
In ObjectsViewModel.kt:
class ObjectsViewModel(private val repository: ObjectsRepository): ViewModel() {
fun getObjects() = repository.getObjects()
}
In ObjectsFragment.kt:
class ObjectsFragment : Fragment(), KodeinAware {
private lateinit var viewModel: ObjectsViewModel
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
viewModel = ViewModelProvider(this, factory).get(ObjectsViewModel::class.java)
// I use the objects in a recyclerview; rvObjectList
rvObjectList.layoutManager = GridLayoutManager(context, gridColumns)
val adapter = ObjectsAdapter(listOf(), viewModel)
// And I use an observer to keep the recyclerview updated
viewModel.getObjects.observe(viewLifecycleOwner, {
adapter.objects = it
adapter.notifyDataSetChanged()
})
}
}
The adapter:
class ObjectsAdapter(var objects: List<Objects>,
private val viewModel: ObjectsViewModel):
RecyclerView.Adapter<ObjectsAdapter.ObjectsViewHolder>() {
// Just a recyclerview adapter
}
Now, all the above works fine - but my problem is that I don't want to use the observer to populate the recyclerview; in the database I store some objects, but there are more objects that I don't want to store.
So, I try to do this instead (in the ObjectsFragment):
var otherObjects: List<Objects>
// ...
if (condition) {
adapter.objects = viewModel.getObjects()
} else {
adapter.objects = otherObjects
}
adapter.notifyDataSetChanged()
And, finally, my problem; I get type mismatch for the true condition assignment:
Type mismatch: inferred type is LiveData<List> but List was expected
I am unable to get my head around this. Isn't this pretty much what is happening in the observer? I know about backing properties, such as explained here, but I don't know how to do that when my data is not defined in the ViewModel.
We need something to switch data source. We pass switching data source event to viewModel.
mySwitch.setOnCheckedChangeListener { _, isChecked ->
viewModel.switchDataSource(isChecked)
}
In viewModel we handle switching data source
(To use switchMap include implementation "androidx.lifecycle:lifecycle-livedata-ktx:2.4.0")
class ObjectsViewModel(private val repository: ObjectsRepository) : ViewModel() {
// Best practice is to keep your data in viewModel. And it is useful for us in this case too.
private val otherObjects = listOf<Objects>()
private val _loadDataFromDataBase = MutableLiveData<Boolean>()
// In case your repository returns liveData of favorite list
// from dataBase replace MutableLiveData(otherObjects) with repository.getFavorite()
fun getObjects() = _loadDataFromDataBase.switchMap {
if (it) repository.getObjects() else MutableLiveData(otherObjects)
}
fun switchDataSource(fromDataBase: Boolean) {
_loadDataFromDataBase.value = fromDataBase
}
}
In activity/fragment observe getObjects()
viewModel.getObjects.observe(viewLifecycleOwner, {
adapter.objects = it
adapter.notifyDataSetChanged()
})
You can do something like this:
var displayDataFromDatabase = true // Choose whatever default fits your use-case
var databaseList = emptyList<Objects>() // List we get from database
val otherList = // The other list that you want to show
toggleSwitch.setOnCheckedChangeListener { _, isChecked ->
displayDataFromDatabase = isChecked // Or the negation of this
// Update adapter to use databaseList or otherList depending upon "isChecked"
}
viewModel.getObjects.observe(viewLifecycleOwner) { list ->
databaseList = list
if(displayDataFromDatabase)
// Update adapter to use this databaseList
}
I'm making an Android alarm app in class. The alarms are displayed inside a recyclerview in the main activity, and I want them to be deleted when pressed. I am able to clear it from the alarm database I set up but I cannot access AlarmManager to cancel the alarm, and the PendingIntent's context also appears to be wrong.
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, index: Int) {
val myViewHolder = holder as MyViewHolder
val sdf = SimpleDateFormat("HH:mm EEEE")
myViewHolder.tvAlarmTime.text = sdf.format(alarms[index].milliseconds)
myViewHolder.tvAlarmFrequency.text = alarms[index].frequency
myViewHolder.itemView.setOnClickListener {
launch {
withContext(Dispatchers.IO) {
val db = AlarmDatabase.getDatabase(myViewHolder.tvAlarmTime.context)
db.alarmDao().deleteTriggeredAlarm((alarms[index].id))
}
}
val pi = PendingIntent.getBroadcast(this, (alarms[index].id).toInt(), Intent("alarmTask"), PendingIntent.FLAG_UPDATE_CURRENT)
val alarmMgr = getSystemService(Context.ALARM_SERVICE) as AlarmManager
alarmMgr.cancel(pi)
}
}
In the last 3 lines, the context has a type mismatch as this is a MyAdapter type - I'm not sure what I need to put here, something similar to MainActivity.context I would assume
getSystemService also shows a type inference error as a string, and I assume this is causing the type mismatch for context.ALARM_SERVICE as a string rather than the context.
What is the correct context and how can I access the AlarmManager inside the adapter?
You can use the context of your item view:
val context = myViewHolder.itemView.context
val pi = PendingIntent.getBroadcast(context, (alarms[index].id).toInt(), Intent("alarmTask"), PendingIntent.FLAG_UPDATE_CURRENT)
val alarmMgr = context.getSystemService(Context.ALARM_SERVICE) as AlarmManager
alarmMgr.cancel(pi)
I am trying to implement deep linking with branch and having issues with the Share Sheet. It just doesn't work. No matter what I click, the relevant action doesn't happen and it just goes back to the bottom of the screen. Even when I click copy, the text doesn't copy. there are no errors so I don't know what's wrong.
This is my code (it is a single item in a recyclerView. I am using GroupieAdapter):
class SingleCommunityOption(val community: Community, val activity : MainActivity) : Item<ViewHolder>() {
private lateinit var buo: BranchUniversalObject
private lateinit var lp: LinkProperties
override fun getLayout(): Int {
return R.layout.community_option_layout
}
override fun bind(viewHolder: ViewHolder, position: Int) {
val firebaseAnalytics = FirebaseAnalytics.getInstance(viewHolder.root.context!!)
val title = viewHolder.itemView.community_option_title
val description = viewHolder.itemView.community_option_description
val memberCount = viewHolder.itemView.community_option_members_count
val share= viewHolder.itemView.community_share
title.text = community.title
description.text = community.description
memberCount.text = "${community.members}"
buo = BranchUniversalObject()
.setCanonicalIdentifier(community.id)
.setTitle(community.title)
.setContentDescription("")
.setContentIndexingMode(BranchUniversalObject.CONTENT_INDEX_MODE.PUBLIC)
.setLocalIndexMode(BranchUniversalObject.CONTENT_INDEX_MODE.PUBLIC)
.setContentMetadata(ContentMetadata().addCustomMetadata("type", "community"))
lp = LinkProperties()
buo.listOnGoogleSearch(viewHolder.root.context)
share.setOnClickListener {
val ss = ShareSheetStyle(activity, "Republic invite", "Join me in this republic.")
.setCopyUrlStyle(activity.resources.getDrawable(android.R.drawable.ic_menu_send), "Copy", "Added to clipboard")
.setMoreOptionStyle(activity.resources.getDrawable(android.R.drawable.ic_menu_search), "Show more")
.addPreferredSharingOption(SharingHelper.SHARE_WITH.FACEBOOK)
.addPreferredSharingOption(SharingHelper.SHARE_WITH.FACEBOOK_MESSENGER)
.addPreferredSharingOption(SharingHelper.SHARE_WITH.WHATS_APP)
.addPreferredSharingOption(SharingHelper.SHARE_WITH.TWITTER)
.setAsFullWidthStyle(true)
.setSharingTitle("Share With")
buo.showShareSheet(activity, lp, ss, object : Branch.BranchLinkShareListener {
override fun onShareLinkDialogLaunched() {}
override fun onShareLinkDialogDismissed() {}
override fun onLinkShareResponse(sharedLink: String, sharedChannel: String, error: BranchError) {}
override fun onChannelSelected(channelName: String) {
firebaseAnalytics.logEvent("community_shared_$channelName", null)
}
})
}
}
}
As I'm learning Kotlin for Android development, I'm now trying the basic programs like hello world and how to navigate from one activity to another activity, there is no issue with this.
When I move from one activity to another, it works fine, but I do not know how to pass the values between the activities.
I tried to set the values in one activity and retrieved them in another activity it does not work.
Please see the code snippet below
This is my main activity where I take the username and password from edit text and setting to the intent:
class MainActivity : AppCompatActivity() {
val userName = null
val password = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
button.setOnClickListener {
val intent = Intent(this#MainActivity,SecondActivity::class.java);
var userName = username.textø
var password = password_field.text
intent.putExtra("Username", userName)
intent.putExtra("Password", password)
startActivity(intent);
}
}
}
This is my second activity where I have to receive values from the main activity
class SecondActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_second)
var strUser: String = intent.getStringExtra("Username")
var strPassword: String = intent.getStringExtra("Password")
user_name.setText("Seelan")
passwor_print.setText("Seelan")
}
}
Please guide me on how to do this, whether I have some other way to do this in Kotlin if not by intent.
Send value from HomeActivity
val intent = Intent(this#HomeActivity,ProfileActivity::class.java)
intent.putExtra("Username","John Doe")
startActivity(intent)
Get values in ProfileActivity
val profileName=intent.getStringExtra("Username")
I'm on mobile, you must test by yourself.
Try to make a CharSequence to a String in MainActivity , you have put a CharSequence rather than a String, for example:
var userName = username.text.toString()
var password = password_field.text.toString()
In Kotlin, you can pass the data simply by using the Intents. You can directly put your data in intent or you can write those data in bundle and send that bundle to another activity using the intent.
val intent = Intent(this#HomeActivity,ProfileActivity::class.java);
intent.putExtra("profileName", "John Doe")
var b = Bundle()
b.putBoolean("isActive", true)
intent.putExtras(b)
startActivity(intent);
You can simply use the intents and bundle to send data from one activity to another activity.
val intent = Intent(this#OneActivity,TwoActivity::class.java);
intent.putExtra("username", userName)
startActivity(intent);
//On Click on Button
var but = findViewById<Button>(R.id.buttionActivity_two) as Button
but.setOnClickListener {
//Define intent
var intent = Intent(applicationContext,MainActivity::class.java)
// Here "first" is key and 123 is value
intent.putExtra("first",123)
startActivity(intent)
}
}
// If Get In Into Other Activity
var Intent1: Intent
Intent1= getIntent()
//Here first is key and 0 is default value
var obj :Int = Intent1.getIntExtra("first",0);
Log.d("mytag","VAlue is==>"+obj)
first you should do this,
var userName = username.text.toString()
var password = password_field.text.toString()
Add Anko dependency.
implementation "org.jetbrains.anko:anko:0.10.4"
information passing inside MainActivity() is like
startActivity<SecondActivity>("Username" to userName,"Password" to password )
get information from SecondActivity() is,
val profileName=intent.getStringExtra("Username")
You can just access the value without using extras or intent. Simply use companion object in MainActivity:
companion object{
val userName: String = String()
val password: String = String()
}
In SecondActivity:
var strUser: String = MainActivity.username
var strPassword: String = MainActivity.password
And you can access the values from multiple activities easily.
Send data
val Name=findViewById<EditText>(R.id.editTextTextPersonName)
val Name2=findViewById<EditText>(R.id.editTextTextPersonName2)
val name=Name.text.toString()
val age=Name2.text.toString()
val intent1=Intent(this,Second::class.java).also {
it.putExtra("Username",name)
it.putExtra("Age",age)
startActivity(it);
}
Receive data
val name=intent.getStringExtra ("Username")
val age = intent.getStringExtra("Age")
val textView5=findViewById<TextView>(R.id.textView).apply {
text= "Name = $name"
}
val textView6=findViewById<TextView>(R.id.textView2).apply {
text= "Age = $age"
}