How can I populate the items of a ListPreference programatically rather than statically from arrays.xml?
SettingsActivity.kt
class SettingsActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.settings_activity)
supportFragmentManager
.beginTransaction()
.replace(R.id.settings, SettingsFragment())
.commit()
supportActionBar?.setDisplayHomeAsUpEnabled(true)
// Do something here to populate the ListPreference bluetoothName...
}
class SettingsFragment : PreferenceFragmentCompat() {
override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
setPreferencesFromResource(R.xml.root_preferences, rootKey)
// ... or here?
// (WTF is a Fragment anyway?)
}
}
}
root_preferences.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.preference.PreferenceScreen
xmlns:app="http://schemas.android.com/apk/res-auto">
<androidx.preference.ListPreference
app:dialogTitle="Select bluetooth adapter"
app:key="bluetoothName"
app:summary="%s"
app:title="Bluetooth adapter" />
<androidx.preference.ListPreference
app:dialogTitle="Select units"
app:entries="#array/units_names"
app:entryValues="#array/units_values"
app:key="units"
app:summary="%s"
app:title="Units"
/>
</androidx.preference.PreferenceScreen>
This seems to work for populating the items, but the app crashes when the user selects one
Process: com.rwb.psamfd, PID: 23596
java.lang.ArrayIndexOutOfBoundsException: length=0; index=1
at androidx.preference.ListPreferenceDialogFragmentCompat.onDialogClosed(ListPreferenceDialogFragmentCompat.java:105)
at androidx.preference.PreferenceDialogFragmentCompat.onDismiss(PreferenceDialogFragmentCompat.java:265)
at androidx.fragment.app.DialogFragment$3.onDismiss(DialogFragment.java:120)
at android.app.Dialog$ListenersHandler.handleMessage(Dialog.java:1323)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
and fuck knows what that means.
You seem to have to give the ListPreference an #array/ otherwise you get IllegalStateException: ListPreference requires an entries array and an entryValues array.
<androidx.preference.ListPreference
app:dialogTitle="Select bluetooth adapter"
app:key="bluetoothName"
app:entries="#array/empty"
app:entryValues="#array/empty"
app:summary="%s"
app:title="Bluetooth adapter" />
<string-array name="empty"></string-array>
class SettingsActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
// get bluetooth devices
var cs: Array<CharSequence> = arrayOf("")
try {
val bt: BluetoothManager =
getSystemService(Context.BLUETOOTH_SERVICE) as BluetoothManager;
val bta: BluetoothAdapter = bt.adapter;
val pairedDevices: Set<BluetoothDevice> = bta.bondedDevices
cs = pairedDevices.map { z -> z.name }.toTypedArray()
}
catch(e:Exception) {}
// Start the fragment
setContentView(R.layout.settings_activity)
supportFragmentManager
.beginTransaction()
.replace(R.id.settings, SettingsFragment(cs))
.commit()
supportActionBar?.setDisplayHomeAsUpEnabled(true)
}
class SettingsFragment(adapters: Array<CharSequence>) : PreferenceFragmentCompat() {
private var adapters: Array<CharSequence> = adapters
override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
setPreferencesFromResource(R.xml.root_preferences, rootKey)
val p:ListPreference? = findPreference<ListPreference>("bluetoothName")
p?.setEntries(adapters)
}
}
}
Turns out you need
p?.setEntryValues(adapters)
as well.
Related
I'm pretty new to kotlin, and I feel pretty much overwhelmed by it. I'd like to ask - how I can display any data from MutableLiveData? I've tried to Log it, but it doesn't seem to work. I've already added the internet permission to the manifest. Here's the code:
ApiServices
interface ApiServices {
#GET("/fixer/latest/")
fun getRatesData(
#Query("base") base: String,
#Query("apikey") apikey: String
): Call<CurrencyModel>
companion object {
private const val url = "https://api.apilayer.com/"
var apiServices: ApiServices? = null
fun getInstance(): ApiServices {
if (apiServices == null) {
val retrofit = Retrofit.Builder()
.baseUrl(url)
.addConverterFactory(GsonConverterFactory.create())
.build()
apiServices = retrofit.create(ApiServices::class.java)
}
return apiServices!!
}
}
}
Repository
class CurrencyRepository constructor(private val apiServices: ApiServices) {
fun getLatestRates() = apiServices.getRatesData("EUR", "API_KEY");
}
ViewModel
class CurrencyViewModel constructor(private val currencyRepository: CurrencyRepository) :
ViewModel() {
val currencyRatesList = MutableLiveData<CurrencyModel>()
val errorMessage = MutableLiveData<String>()
fun getLatestRates() {
val response = currencyRepository.getLatestRates();
response.enqueue(object : retrofit2.Callback<CurrencyModel> {
override fun onResponse(
call: retrofit2.Call<CurrencyModel>,
response: Response<CurrencyModel>
) {
currencyRatesList.postValue(response.body())
}
override fun onFailure(call: retrofit2.Call<CurrencyModel>, t: Throwable) {
errorMessage.postValue(t.message)
}
})
}
}
FactoryViewModel
class CurrencyViewModelFactory constructor(private val repository: CurrencyRepository) :
ViewModelProvider.Factory {
override fun <T : ViewModel?> create(modelClass: Class<T>): T {
return if (modelClass.isAssignableFrom(CurrencyViewModel::class.java)) {
CurrencyViewModel(this.repository) as T
}else{
throw IllegalArgumentException("Couldn't found ViewModel")
}
}
}
MainActivity
class MainActivity : AppCompatActivity() {
private val retrofitService = ApiServices.getInstance()
lateinit var viewModel: CurrencyViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
viewModel = ViewModelProvider(this, CurrencyViewModelFactory(CurrencyRepository(retrofitService)))
.get(CurrencyViewModel::class.java)
viewModel.currencyRatesList.observe(this, Observer {
Log.d(TAG, "onCreate: $it")
})
viewModel.errorMessage.observe(this, Observer {
viewModel.getLatestRates()
})
}
}
You never call viewModel.getLatestRates() in your onCreate() to fetch an initial value for your LiveData, so it never emits anything to observe. The only place you have called it is inside your error listener, which won't be called until a fetch returns an error.
Side note, I recommend naming the function "fetchLatestRates()". By convention, "get" implies that the function returns what it's getting immediately rather than passing it to a LiveData later when its ready.
And a tip. Instead of this:
class MainActivity : AppCompatActivity() {
lateinit var viewModel: CurrencyViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
// ...
viewModel = ViewModelProvider(this, CurrencyViewModelFactory(CurrencyRepository(retrofitService)))
.get(CurrencyViewModel::class.java)
//...
}
}
You can do this for the same result:
class MainActivity : AppCompatActivity() {
val viewModel: CurrencyViewModel by viewModels(CurrencyViewModelFactory(CurrencyRepository(retrofitService)))
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
// ...
}
}
I have problem with RecyclerView into ViewModel.
RecyclerView without viewmodel working perfect.
My MainFragment:
private lateinit var shoppingListViewModel: ShoppingListViewModel
private lateinit var categoryAdapter: CategoryAdapter
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
shoppingListViewModel = ViewModelProvider(requireActivity())[ShoppingListViewModel::class.java]
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
binding.categoryRV.layoutManager = LinearLayoutManager(requireContext())
shoppingListViewModel.allCategories.observe(viewLifecycleOwner, { <-- when I add this line,
updateCategories(it) crashing my app
})
}
private fun updateCategories(list: List<Category>) {
categoryAdapter = CategoryAdapter(list)
binding.categoryRV.adapter = categoryAdapter
}
My ViewModel:
class ShoppingListViewModel(application: Application) : AndroidViewModel(application) {
private val repository = Repository(application)
val allCategories = repository.showAllCategories()
}
My Repo:
class Repository(app: Application) {
private val shoppingListsDao = ShoppingListDatabaseBuilder.getInstance(app.applicationContext).shoppingListDao()
fun showAllCategories(): LiveData<List<Category>> {
return shoppingListsDao.showAllCategories()
}
}
My Interface Dao:
#Dao
interface ShoppingListDao {
#Query("SELECT * FROM category")
fun showAllCategories(): LiveData<List<Category>>
}
Everything looks good, no errors. I don't know what going on :(
I find my problem.
I need to update of version DB :)
The problem is related to the fact that I don't manage to implement a OnItemClick listener for a RecyclerView that is located in a "mainFragment" by implementing the OnClickListener in the Adapter.
I would like my application (kotlin) to launch another fragment ("deletePage" in the code bellow) everytime an itemView (an ImageView) from the RecyclerView is clicked, this fragment would display the same photo in big.
My Adapter code is the following one:
class MyAdapter : RecyclerView.Adapter<MyAdapter.MyViewHolder>() {
private var photo = emptyList<Photo>()
inner class MyViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView)
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
return MyViewHolder(
LayoutInflater.from(parent.context).inflate(R.layout.row_layout, parent, false)
)
}
override fun getItemCount(): Int {
return photo.size
}
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
holder.itemView.longitude.text = photo[position].latitude
holder.itemView.latitude.text = photo[position].longitude
holder.itemView.imageView.load(photo[position].photo)
}
fun setData(photo: List<Photo>) {
this.photo = photo
notifyDataSetChanged()
}
}
And my mainFragment code is the following one:
class MainFragment : Fragment(){
private lateinit var myView: MyViewModel
private val adapter by lazy { MyAdapter() }
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
val view = inflater.inflate(R.layout.fragment_main, container, false)
//Recyclerview
val adapter = MyAdapter()
val recyclerView = view.recycler_view
recyclerView.adapter = adapter
recyclerView.layoutManager = LinearLayoutManager(requireContext())
myView = ViewModelProvider(this).get(MyViewModel::class.java)
myView.readPhoto.observe(viewLifecycleOwner, Observer {photo ->
adapter.setData(photo)
})
setHasOptionsMenu(true)
return view
}
override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
inflater.inflate(R.menu.menu_database, menu)
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
when {
item.itemId == R.id.deleteAll -> findNavController().navigate(R.id.deletePage)
item.itemId == R.id.refresh -> {
Toast.makeText(activity, "yep", Toast.LENGTH_SHORT).show()
instertDataToDatabase()
}
}
if (item.itemId == R.id.deleteAll) {
}
return super.onOptionsItemSelected(item)
}
}
The objective is that when you click on an item of the RecyclerView the "findNavController().navigate(R.id.deletePage)" fragment is displayed but everytime I try to implement a solution the application crashes when clicking at an item of the RecyclerView. Right now the navigation works by the click on a button in the Menu at the toolbar but is not the ideal solution.
Any sort of help or advice would be very much appreciated!
Firstly you need to give click listener of your itemView in onBindViewHolder
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
holder.itemView.longitude.text = photo[position].latitude
holder.itemView.latitude.text = photo[position].longitude
holder.itemView.imageView.load(photo[position].photo)
holder.itemView.setOnClickListener { navigateToFragment() }
}
For the navigation somehow you should have a context instance.
Here is the possible solutions that came up to my mind:
Give navigator instance to adapter
class Navigator(fragment: Fragment) {
private val fragmentRef = WeakReference(fragment)
fun navigate(){
// make your navigations here with using fragmentRef.get()
}
}
In your fragment:
private val navigator = Navigator(this)
...
val adapter = MyAdapter(navigator)
In your adapter:
class MyAdapter(private val navigator: Navigator) : RecyclerView.Adapter<MyAdapter.MyViewHolder>() {
fun navigateToFragment(){
navigator.navigate()
}
Make interface for callback
2.1. Implement that interface in fragment and give adapter the interface instance
interface Navigable{
fun navigate()
}
In your fragment:
class MainFragment : Fragment(), Navigable{
...
override fun navigate(){
// make your navigation
}
val adapter = MyAdapter(navigator)
In your adapter:
class MyAdapter(private val navigable: Navigable) : RecyclerView.Adapter<MyAdapter.MyViewHolder>() {
fun navigateToFragment(){
navigable.navigate()
}
2.2. Make the interface, but do not pass reference, use findFragment in adapter
In your adapter: override onAttachedToRecyclerView to find fragment
private lateinit var navigable: Navigable
override fun onAttachedToRecyclerView(recyclerView: RecyclerView) {
super.onAttachedToRecyclerView(recyclerView)
navigable = recyclerView.findFragment<Fragment>() as Navigable
}
fun navigateToFragment(){
navigable.navigate()
}
I'm new android learner, I'm trying to make a RecyclerView contains of List of (Stories Title, and Stories images).
When you click on an item in the RecyclerView it should open a new activity called ChildrenStoriesPreview contains of ScrollView which have ImageView to put the Story Image in it and TextView to put the Text of the Story in it.
the problem is that I don't know how to set ocItemClickListener to know which item is clicked and how the new activity will contain information depending on this item? Could you please help me?
here is my Main.kt
class MainChildrenStories : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main_children_stories)
var childrenStoriesArraylist = ArrayList<ChildrenStoriesRecyclerView>()
childrenStoriesArraylist.add(ChildrenStoriesRecyclerView("Story1", R.drawable.pic1))
childrenStoriesArraylist.add(ChildrenStoriesRecyclerView("Story2", R.drawable.pic2))
childrenStoriesArraylist.add(ChildrenStoriesRecyclerView("Story3", R.drawable.pic3))
children_stories_recyclerview.layoutManager = LinearLayoutManager(this, LinearLayout.VERTICAL, false)
val childrenStoriesAdapter = ChildrenStoriesAdapter(childrenStoriesArraylist)
children_stories_recyclerview.adapter = childrenStoriesAdapter
childrenStoriesAdapter.setOnItemClickListener(object : ChildrenStoriesAdapter.ClickListener {
override fun onClick(pos: Int, aView: View) {
//The App Crash here
if (pos == 0){
my_text_view.text = "Story number 1"
my_imageview.setImageResource(R.drawable.pic1)
}else if (pos == 1){
my_text_view.text = "Story number 2"
my_imageview.setImageResource(R.drawable.pic2)
}
val intent = Intent(this#MainChildrenStories, ChildrenStoryPreview::class.java)
startActivity(intent)
}
})
}
}
MyRecyclerView Class
data class ChildrenStoriesRecyclerView(var mStoryName: String, var mStoryImage: Int)
My RecyclerView Adapter Class
class ChildrenStoriesAdapter(var myArrayList: ArrayList<ChildrenStoriesRecyclerView>) :
RecyclerView.Adapter<ChildrenStoriesAdapter.ViewHolder>() {
lateinit var mClickListener: ClickListener
fun setOnItemClickListener(aClickListener: ClickListener) {
mClickListener = aClickListener
}
override fun onCreateViewHolder(p0: ViewGroup, p1: Int): ViewHolder {
val v = LayoutInflater.from(p0.context).inflate(R.layout.children_stories_list, p0, false)
return ViewHolder(v)
}
override fun getItemCount(): Int {
return myArrayList.size
}
override fun onBindViewHolder(p0: ViewHolder, p1: Int) {
var infList = myArrayList[p1]
p0.storyName.text = infList.mStoryName
p0.storyImage.setImageResource(infList.mStoryImage)
}
inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView), View.OnClickListener {
override fun onClick(v: View) {
mClickListener.onClick(adapterPosition, v)
}
val storyName = itemView.findViewById(R.id.txtStoryName) as TextView
val storyImage = itemView.findViewById(R.id.imageViewChildrenStories) as ImageView
init {
itemView.setOnClickListener(this)
}
}
interface ClickListener {
fun onClick(pos: Int, aView: View)
}
}
My new Activity To show Details of the Story
class ChildrenStoryPreview : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_children_story_preview)
}
}
Pass the Event Listener to Adapter constructor also to viewholder to catch view holder (items) clicks.
class ChildrenStoriesAdapter(var myArrayList: ArrayList<ChildrenStoriesRecyclerView>
var clickListener:MyClickListener?) :
RecyclerView.Adapter<ChildrenStoriesAdapter.ViewHolder>() {
...
override fun onCreateViewHolder(p0: ViewGroup, p1: Int): ViewHolder {
val v = LayoutInflater.from(p0.context).inflate(R.layout.children_stories_list, p0, false)
return ViewHolder(v, clickListener)
}
...
inner class ViewHolder(itemView: View, clickListener:MyClickListener?) :
RecyclerView.ViewHolder(itemView) {
itemView.setOnClickListener { clickListener?.myClickedFun(...) }
...
class ChildrenStoryPreview : AppCompatActivity(), MyClickListener {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_children_story_preview)
}
override fun myClickedFun(...) {
...
}
}
Later init adapter like
..
val childrenStoriesAdapter = ChildrenStoriesAdapter(childrenStoriesArraylist, this)
Follow this tutorial: Android - Start Another Activity if I made MainActivity.java button OnClick attribute has the sendMessage() method.
But if I made MainActivity.kt button OnClick attribute has nothing to show, just a none.
Is this an Android Studio 3 bug or I missed something for Kotlin?
Java mainActivity:
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
/** Called when the user taps the Send button */
public void sendMessage(View view) {
// Do something in response to button
}
}
Kotlin mainActivity:
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
}
/** Called when the user taps the Send button */
fun sendMessage(view: View) {
// Do something in response to button
}
}
XML layout (Java and Kotlin project are the same)
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="ir.bigbang.vahid.myapplication.MainActivity">
<Button
android:id="#+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button"
tools:layout_editor_absoluteX="148dp"
tools:layout_editor_absoluteY="81dp" />
</android.support.constraint.ConstraintLayout>
It seems like the designer does not support Kotlin yet. Here are some solution:
XML (Not Recommended)
Add the following line to your Button tag. This is exactly what the designer will do.
android:onClick="sendMessage"
Old Fashion
No need to add anything.
val button = findViewById<Button>(R.id.Button)
button.setOnClickListener {
}
kotlin-android-extensions (Recommended)
Add apply plugin: "kotlin-android-extensions" to your build.gradle
// button is the Button id
button.setOnClickListener {
}
Your code will like this:
button.setOnClickListener(){
Toast.makeText(this#MainActivity, "Its toast!", Toast.LENGTH_SHORT).show();
}
Here import will:
import kotlinx.android.synthetic.main. activity_main.*
Here "button" is the id of that Button in .xml file. Here the advantage is no need to create Button object in your java class.
Once defined the sendMessage class as :
/** Called when the user taps the Send button */
fun sendMessage(view: View) {
setContentView(R.layout.activity_second)
// Do something in response to button
}
And also defined a second activity as:
class SecondActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_second)
}
}
I added the SendMessage to the OnClick function:
And then it worked.
You can easily define this inside the XML itself. But using the android:onClick attribute is still a little expensive.
Instead you could consider using the Kotlin Android Extensions and synthetic properties:
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
button.setOnClickListener {
// Do something in response to button
}
}
Button OnClick implementation it's can be done by some ways in Android
some of the possible ways are below in sample:
1>Using OnClickListener as a interface
Here we implement our main activity with OnClicklistener
and override the function onClick
override fun onClick(v: View?) {
when (v?.id){
(R.id.btn1) -> {
toastmsg("Button1");
}
R.id.btn2 -> {
toastmsg("Button2");
}
}
}
2>And create a function and pass the OnClickListener with
variable sample:
findViewById<Button>(R.id.btn3).setOnClickListener(btnClick);
var btnClick =
OnClickListener {
Toast.makeText(this, "BtnClick", Toast.LENGTH_SHORT).show() ;
}
3>Create OnClickListener in Oncreate()
btn1=findViewById(R.id.btn1);
btn1?.setOnClickListener {
toastmsg("test button1");
}
full sample Code of the example it contains all the possible implementation of the Button OnClickListener :
class MainActivity : AppCompatActivity() , OnClickListener{
lateinit var tv1:TextView;
lateinit var tv2:TextView;
lateinit var tv3:TextView;
var btn1: Button? =null;
var btn2: Button? =null;
var btn3: Button? =null;
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
btn1=findViewById(R.id.btn1);
btn1?.setOnClickListener {
toastmsg("test button1");
}
findViewById<Button>(R.id.btn2).setOnClickListener(this);
findViewById<Button>(R.id.btn3).setOnClickListener(btnClick);
}
var btnClick =
OnClickListener {
Toast.makeText(this, "BtnClick", Toast.LENGTH_SHORT).show() ;
}
override fun onClick(v: View?) {
when (v?.id){
(R.id.btn1) -> {
toastmsg("Button1");
}
R.id.btn2 -> {
toastmsg("Button2");
}
}
}
private fun toastmsg(msg: String){
Toast.makeText(this, "DaggerTest" + msg, Toast.LENGTH_SHORT).show();
}
}
Here's the solution I came up with in the MainActivity.kt file.
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val button = findViewById<Button>(R.id.button)
button.setOnClickListener {
sendMessage()
}
}
/** Called when the user taps the Send button */
private fun sendMessage() {
val editText = findViewById<EditText>(R.id.editText)
val message = editText.text.toString()
val intent = Intent(this, DisplayMessageActivity::class.java).apply
{
putExtra(EXTRA_MESSAGE, message)
}
startActivity(intent)
}