I created a RatingBar in my application. It is for rating movies. I want value to be saved. When I login and go to that activity, I want to see that stars that I rated. It is difficult for me to find the answer because it is written in Kotlin and I'm new to it.
I searched for many other questions and answers, but with no result. Can you tell me what I need to change in my code?
class MovieDetailsActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_movie_details)
fiveStars()
val sharedPreference = getPreferences(Context.MODE_PRIVATE)
val rating = sharedPreference.getFloat("numStars", 0f)
ratingBar.rating = rating
}
private fun fiveStars() {
val ratingBar = findViewById<RatingBar>(R.id.ratingBar)
ratingBar.onRatingBarChangeListener = RatingBar.OnRatingBarChangeListener()
{ ratingBar: RatingBar, fl: Float, b: Boolean ->
val sharedPreference = getSharedPreferences("numStars", Context.MODE_PRIVATE)
val editor = sharedPreference.edit()
editor.putFloat("numStars", fl)
editor.apply()
Log.d("rate", ratingBar.rating.toString())
}
}
}
I tried a lot of things, but nothing is working. Hope you could help me. Thanks!
It seems like you're using two different preferences.
Here you are calling getPreferences(Context.MODE_PRIVATE):
val sharedPreference = getPreferences(Context.MODE_PRIVATE)
val rating = sharedPreference.getFloat("numStars", 0f)
ratingBar.rating = rating
and here you are using a specific sharedPreferences:
val sharedPreference = getSharedPreferences("numStars", Context.MODE_PRIVATE)
val editor = sharedPreference.edit()
Either use getPreferences(Context.MODE_PRIVATE) in both cases, or use getSharedPreferences("numStars", Context.MODE_PRIVATE) in both cases
Related
In my SettingActivity I'm loading some data to be shown in ListPreference from Room, once the items are selected all works correctly, the value is saved to `SharedPreferences and the summary is shown correctly, but once I return to SettingsActivity the summary value is reset to null.
Here is what is happening:
My code is pretty simple, onViewCreated() I start observing LiveData to be shown in ListPreference and then I set the values for entries and entryValues
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
viewModel.shops.observe(viewLifecycleOwner) {
setShopsPreferences(it)
}
}
private fun setShopsPreferences(shops: List<Shop>) {
val shopsPreference = preferenceManager.findPreference<ListPreference>("defaultShop")
if (shops.isEmpty()) {
shopsPreference?.isEnabled = false
return
} else {
shopsPreference?.isEnabled = true
}
val entries: ArrayList<String> = ArrayList()
val entryValues: ArrayList<String> = ArrayList()
shops.forEach {
entries.add(it.description)
entryValues.add(it.id)
}
shopsPreference?.entryValues = entryValues.toArray(arrayOfNulls<CharSequence>(entryValues.size))
shopsPreference?.entries = entries.toArray(arrayOfNulls<CharSequence>(entries.size))
}
ViewModel:
#HiltViewModel
class ShopsViewModel #Inject constructor(repository: ShopsRepository) : ViewModel() {
private val _shops = MutableLiveData<List<Shop>>()
val shops: LiveData<List<Shop>> = _shops
init {
repository.getAllShops().observeForever {
_shops.value = it
}
}
}
Repository:
fun getAllShops(): LiveData<List<Shop>> {
return shops.select()
}
DAO:
#Dao
interface ShopsDAO {
#Query("SELECT * FROM shops")
fun select(): LiveData<List<Shop>>
}
You are populating list entries dynamically after the preference hierarchy is already created by inflating the xml. But during that time there was no entry, hence the value was null. The data was then retrieved asynchronously but the change will not be reflected. So you have to set the summary manually.
Another approach I'm not sure about is to call recreate on the activity after populating the data inside the observer listener.
To resolve the issue with dynamic data in a ListPreference I've made some changes to my code, first of call in onCreatePreferences() I've added a preference listener to my ListPreference like this:
override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
setPreferencesFromResource(R.xml.root_preferences, rootKey)
val shopsPreference = preferenceManager.findPreference<ListPreference>("defaultShop")
shopsPreference?.setOnPreferenceChangeListener { preference, newValue ->
val description = viewModel.shops.value?.find { it.id == newValue }
preference.summary = description?.description
true
}
}
So in that way on each new selection, I'm looking for the matching value for that preference in my ViewModel and getting the description for it which then is set as the summary.
While to set the summary every time the list has been changed or the SettingsActivity is opened I've added the following code to my setShopsPreferences() function:
private fun setShopsPreferences(shops: List<Shop>?) {
if (shops == null) {
return
}
val shopsPreference = preferenceManager.findPreference<ListPreference>("defaultShop")
// The preference is enabled only if there are shows inside the list
shopsPreference?.isEnabled = shops.isNotEmpty()
// Getting the defaultShop preference value, which will be used to find the actual shop description
val defaultShop = sharedPreferences.getString("defaultShop", "0")
defaultShop?.let { shopId ->
// Setting the summary based on defaultShop saved preference
shopsPreference?.summary = shops.find { it.id == shopId }?.description
}
val entries: ArrayList<String> = ArrayList()
val entryValues: ArrayList<String> = ArrayList()
shops.forEach {
entries.add(it.description)
entryValues.add(it.id)
}
shopsPreference?.entryValues =
entryValues.toArray(arrayOfNulls<CharSequence>(entryValues.size))
shopsPreference?.entries = entries.toArray(arrayOfNulls<CharSequence>(entries.size))
}
I am getting some kind of empty string Amount function but dont know as im passing not null and non empty string
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val editText: EditText = findViewById(R.id.cost_of_service)
val radioGroup: RadioGroup = findViewById(R.id.tip_options)
val cal: Button = findViewById(R.id.calculate_button)
val message: String = editText.text.toString()
val tv: TextView = findViewById(R.id.tip_result)
getSignal(radioGroup, cal, message, tv)
}
private fun getSignal(radioGroup: RadioGroup, cal: Button, message: String, tv: TextView){
cal.setOnClickListener{
val selectedRB: RadioButton = findViewById(radioGroup!!.checkedRadioButtonId) //selectedRB -> selected radio button id
val per: String = selectedRB.text.toString()
val amount: Double = Amount(per, message)
tv.text = amount.toString()
}
}
private fun Amount(per: String, message: String): Double {
return message.toDouble() + (message.toInt() * per.toInt()) / 100
}
val message: String = editText.text.toString()
That gets the value of the editText at the time its called. It does not update it as it changes. Since you're calling this in onCreate, its almost certainly empty. And since it's empty, its not a numbver so trying to convert it to one fails.
The fix for this is to put this inside your onClickListener. Do the same for every field you want to get the text out of.
So I'm trying to learn Kotlin and i'm a few days in. I am trying to build a Coin Calculator app that will take input of quantity of each type of coin you have and then using a class value it will add up all your change and tell you a total. I apologize for not being able to be too specific other than my error: None of the following functions can be called with the arguments supplied:
public final operator fun times(other: Byte): Double defined in kotlin.Double
public final operator fun times(other: Double): Double defined in kotlin.Double
it's showing these on my quarter total and dime total variables.
As I said I am new and actively studying looking for insight on what I am doing wrong, also any other advice over my messy coding that you see would be greatly appreciated.
-Thanks!
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
//MyCode
val submitButton: Button = findViewById(R.id.submit)
var quarterQuan: EditText = findViewById(R.id.quarterInput)
var dimeQuan: EditText = findViewById(R.id.dimeInput)
submitButton.setOnClickListener{
val dime = Dime()
val quarter= Quarter()
var quarterTotal: Float = quarter.quarterVal*quarterQuan
var dimeTotal: Float = dime.dimeVal*dimeQuan
var cashTotal: Float = dimeTotal + quarterTotal
val resultTextViewLabel: TextView = findViewById(R.id.textResult)
resultTextViewLabel.text = cashTotal.toString()
}
}
}
class Quarter(){
val quarterVal = 0.25
}
class Dime(){
val dimeVal = 0.10
}
quarterQuan and dimeQuan are of type EditText (they are not numbers) and cannot be multiplied with a Float.
What you need to do is to read the values of these EditTexts:
val quarterEditTextValue = quarterQuan.text.toString().toFloat()
val dimeEditTextValue = dimeQuan.text.toString().toFloat()
You can then use these values for multiplication
var quarterTotal = quarter.quarterVal*quarterEditTextValue
var dimeTotal = dime.dimeVal*dimeEditTextValue
Have to add that you need to make each initial EditText value to be 0.0 to avoid NumberFormatException.
<EditText
android:id="#+id/quarterInput"
android:text="0.0" .... />
sorry for newbie question but I'm starting with Kotlin and Android app development. Currently I'm trying to create simple Activity that will switch background colors. I add 2 buttons that are working and switching colors between white and green, but would you be able to help me how to save it between the session using sharedPreferences ? I cannot retrieve these states from the preferences. Code sample below:
class OptionsActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_options)
val prefs = getSharedPreferences("bgColour", Context.MODE_PRIVATE)
val editor = prefs.edit()
bt3.setOnClickListener {
Screen.setBackgroundColor(Color.GREEN)
}
bt4.setOnClickListener {
Screen.setBackgroundColor(Color.WHITE)
}
}
}
You need to save the color in your preferences:
val prefs = getSharedPreferences("bgColour", Context.MODE_PRIVATE)
//Retrieve the saved value, default is false.
if (prefs.getBoolean("isGreen", false)) {
Screen.setBackgroundColor(Color.GREEN)
} else {
Screen.setBackgroundColor(Color.WHITE)
}
val editor = prefs.edit()
//Save on button click
bt3.setOnClickListener {
Screen.setBackgroundColor(Color.GREEN)
editor.putBoolean("isGreen", true)
editor.apply()
}
bt4.setOnClickListener {
Screen.setBackgroundColor(Color.WHITE)
editor.putBoolean("isGreen", false)
editor.apply()
}
You can read more about saving key-value pairs here.
I'm trying to do a function that will only save a higher speed than the one already saved.
But the var outside the if loop is always 0.0, inside value is different. Does anyone knows some resolve or even better idea how to save only maximum speed?
private fun updateUI(speed: Double, distance: Double){
val df = DecimalFormat("0.0")
speed_text_view.text = df.format(speed).plus(" km/h")
distance_text_view.text = df.format(distance)
Log.e("getLocationUpdates", df.format(speed))
var getSpeedDouble = 0.0 //here is problem. The value doesn't change
if (speed > getSpeedDouble) {
val sharedPref = PreferenceManager.getDefaultSharedPreferences(this)
val editor = sharedPref.edit()
editor
.putString("SPEED", speed.toString())
.apply()
val getSharedPref = PreferenceManager.getDefaultSharedPreferences(this)
getSharedPref.apply {
val getSpeed = getString("SPEED", "")
getSpeedDouble = getSpeed!!.toDouble()
Log.e("GetSpeedDouble", getSpeedDouble.toString())
max_speed_text_view.text = getSpeed.toString()
}
}
}
For posterity:
Have the speed as a global variable.
val speed:Double = 0.0
when you load the activity fetch its value from the shared preferences:
val preference = getSharedPreferences(yourApp, Context.MODE_PRIVATE)
val editor = preference.edit()
speed = preference.getDouble(“SPEED”,0.0)
when you finish the activity write the value back to the shared preferences:
editor.putDouble(“SPEED”,speed)
editor.commit()
within your method just assign a new value to the variable only if the current reading is bigger than the saved value.
private fun updateUI(newSpeed:Double) {
if (newSpeed > speed)
{
speed = newSpeed
textview.setText((newSpeed).toString())
}
}
How about putting it away in a nice class, and when just initializing that class from you activity:
speedKeeper = MaxSpeedKeeper(this)
then all you have to do is drop in your speeds (ie. speedKeeper.speed = 10.4) and it will stay updated.
Apply() will update to disk async, but the value in initialized sharedPref will stay cached, and is read from companion object's maxSpeed anyway.
This way, you can just drop your speedkeeper in any other processes, classes, fragments etc and it will keep doing what it does, or just initialize it again in a new activity.
class MaxSpeedKeeper(context: Context) {
companion object {
const val SPEED = "SPEED"
const val SHAREDPREFS_NAME = "MY_SHAREDPREFS"
var maxSpeed = 0.0f
}
var speed: Double
get() = maxSpeed.toDouble()
set(speedToCheck) {
if (speedToCheck > maxSpeed) {
maxSpeed=speedToCheck.toFloat()
with(sharedPref.edit()) {
putFloat(SPEED, speedToCheck.toFloat()) // you could change this to a string or bits or something if you want more resolution than a float gives
apply()
}
}
}
private val sharedPref =
context.getSharedPreferences(SHAREDPREFS_NAME, Context.MODE_PRIVATE)
init {
maxSpeed = sharedPref.getFloat(SPEED, 0.0f)
}
}
private fun updateUI(speed: Double) {
var getSpeedDouble = 0.0 //here is problem. The value doesn't change
if (speed > getSpeedDouble) {
val sharedPref = PreferenceManager.getDefaultSharedPreferences(this)
val editor = sharedPref.edit()
editor.putString("SPEED", speed.toString()).apply()
val defaultSpeed = sharedPref.getString("SPEED", "")
getSpeedDouble = defaultSpeed.toString().toDouble()
Log.e("updateUI", getSpeedDouble.toString())
}
}
private fun getSpeed() {
var getSpeedDouble: Double
val sharedPref = PreferenceManager.getDefaultSharedPreferences(this)
val defaultSpeed = sharedPref.getString("SPEED", "")
getSpeedDouble = defaultSpeed.toString().toDouble()
Log.e("getSpeed", getSpeedDouble.toString())
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
updateUI(10.0)
getSpeed()
}
output
updateUI: 10.0
getSpeed: 10.0