Develop Reference

Kotlin - Get new index of item in shuffled list

I have a multiple choice quiz with 4 choices per answer. In the ArrayList with the questions and choices, the correct answer is set to the index of the correct option. I want to shuffle the choices but am not sure how to identify the new index of the correct answer. Any thoughts?
Question object
object ConstantsAnalysis {
const val TOTAL_CORRECT: String = "total_correct"
const val TOTAL_OPP: String = "total_opp"
fun getQuestions3(): ArrayList<Questions3> {
val questionList = ArrayList<Questions3>()
val q1 = Questions3(1, null,
"On a graph, the horizontal line along which data are plotted is the _____",
"y axis", "x axis", "origin", "quadrant", 2, R.string.Jones_1995, null)
questionList.addAll(listOf(q1))
questionList.shuffle()
return questionList
}
}
Data class
data class Questions3(
val id: Int, val image: Int?, val question: String, val option1: String, val option2: String,
val option3: String, val option4: String, val correctAnswer: Int, val dialogBox: Int?, val dialogBox2: Int?)
Shuffle choices
val ansorder = arrayOf(question.option1, question.option2, question.option3, question.option4)
ansorder.shuffle()
radio_button1.text = ansorder[0]
radio_button2.text = ansorder[1]
radio_button3.text = ansorder[2]
radio_button4.text = ansorder[3]
Check answer choice
if (questions3!!.correctAnswer != mSelectedOptionPosition) {
//do x
}
Edit (Since correct answer is a string and the index changes after shuffling, answerView(questions3.correctAnswer, R.drawable.correct_option_border.
class QuestionsActivityAnalysis : AppCompatActivity(), View.OnClickListener {
private var mCurrentPosition:Int = 1
private var mQuestionsList:ArrayList<Questions3>? = null
private var mSelectedOptionPosition:Int = 0
private var mCorrectAnswers: Int = 0
private var mSelectedOptionText: String? = null
private fun shuffle() {
val question = mQuestionsList!![mCurrentPosition - 1]
val ansorder = arrayOf(question.option1, question.option2, question.option3, question.option4)
ansorder.shuffle()
radio_button1.text = ansorder[0]
radio_button2.text = ansorder[1]
radio_button3.text = ansorder[2]
radio_button4.text = ansorder[3]
}
override fun onClick(v: View?) {
when(v?.id){
R.id.radio_button1 -> { selectedOptionView(radio_button1, 1)
mSelectedOptionText = radio_button1.text as String?
}
R.id.radio_button2 -> { selectedOptionView(radio_button2, 2)
mSelectedOptionText = radio_button2.text as String?
}
R.id.radio_button3 -> { selectedOptionView(radio_button3, 3)
mSelectedOptionText = radio_button3.text as String?
}
R.id.radio_button4 -> { selectedOptionView(radio_button4, 4)
mSelectedOptionText = radio_button4.text as String?
}
R.id.btn_submit -> {
val questions3 = mQuestionsList?.get(mCurrentPosition - 1)
if (questions3!!.correctAnswer != mSelectedOptionText) {
} else {
mCorrectAnswers++
}
answerView(questions3.correctAnswer, R.drawable.correct_option_border)
private fun answerView(answer: Int, drawableView: Int) {
when(answer){
1 -> {
radio_button1.background = ContextCompat.getDrawable(this, drawableView)
}
2 -> {
radio_button2.background = ContextCompat.getDrawable(this, drawableView)
}
3 -> {
radio_button3.background = ContextCompat.getDrawable(this, drawableView)
}
4 -> {
radio_button4.background = ContextCompat.getDrawable(this, drawableView)
}
}
}

I would really recommend just creating a data class like this:
data class QuestionOption(val question:String, val isCorrect = false)
Afterwards you can shuffle any way you like and just check if the selected QuestionOption has isCorrect set to true. You get a bunch of benefits and the logic gets simpler.
Edit:
To make it easier to declare questions this way:
In general if you add questions in your code you want only as much necessary code as required. For this you can either declare a good constructor or a function that basically maps your values to a constructor. In your case I'd say
data class Questions3(
val id: Int, val question: String, val option1: String, val option2: String,
val option3: String, val correctOption: String, val image: Int?=null,val dialogBox1: Int?=null,val dialogBox2: Int?=null)
(notice how the optional parameters are last, you don't need to specify them as well thanks to them beeing null by default)
Makes sense, in theory you could also (not too clean but easy) just shuffle option 1-3 & correctOption and then just compare if the correctOption String matches the selected String.
Otherwise as I said, you can always create logic for mapping stuff. Here you can either map from Constructor to another Constructor, same with Functions that return a finished Object.

Init property in method called in initialization

I am trying to start with Kotlin. I have a question about initializing properties in the init method. I want to init a property in a method I call in the init block. However this gives the error that the property is not initialized. When I set a property in the init method there is no problem:
private var rippleColor: Int
init {
rippleColor = 1;
}
When I do it through another method I get the error I described earlier:
private var rippleColor: Int
init {
setDefaultRippleColor(context)
}
fun setDefaultRippleColor(context: Context) {
val attrs: IntArray = intArrayOf(R.attr.colorControlHighlight)
var a = context.obtainStyledAttributes(attrs)
rippleColor = a.getColor(0, Color.RED)
a.recycle()
}
Is it possible to do it like I want to do or is it just not possible?

If you are sure the property will get initialized then you can set an arbitrary value.
private var rippleColor: Int = 0
the value of the rippleColor is then replaced by a.getColor(0, Color.RED) in the setDefaultRippleColor method

You can use the following code.
private var rippleColor: Int = Int.MIN_VALUE
init {
setDefaultRippleColor(context)
}
private fun setDefaultRippleColor(context: Context){
val attrs: IntArray = intArrayOf(R.attr.colorControlHighlight)
val a = context.obtainStyledAttributes(attrs)
rippleColor = a.getColor(0, Color.RED)
a.recycle()
}

Function to animate an ImageView in a RecyclerView

To forward my application, i need a function that will rotate an imageView in a recyclerView.
The recyclerView is one of 3 recyclerviews that are already working well, and are clickable through a cardView.
shortvideo there:
https://mega.nz/#!W6AyAYaY!07WG8kr_POYiGsgt0yja6fk8RaclZLw2-MiMFrmEQmk
I created Classes with a few members, which permit to know the state of the objects.
I am newbie in Android programmation, and it was difficult for me to make these recyclerView working well :-)
7 April : i finally succeeded to implement my function
but the result is weird !
can see there :
https://mega.nz/#!DzI2iaiB!VBG9Ex4TZlAsoUYPSRhXXMP4weH-9hXyjbqF1nCRyeA
There is an imageView which is rotating, but this is the left one, not the clicked one, and there is a mix, a swap between pictures.
My question is : are the imageViews clickable and focusable like cardViews ?
if so i can try to make the imageView focusable and clickable (actually the cardView is... )
What about the index is recyclerViews ? isn't it the cardview which is clicked which has the index ? or the left one in the screen ?
I am puzzled :-)
Following: the layout with CardView and imageView; MainActivity where i tried to write the function; and the Adapter for the Top RecyclerView where the function is supposed to
rotate (180 °) the imageView at the index ( index, tag and position )
no change about that xml file
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto">
<androidx.cardview.widget.CardView
android:id="#+id/flag_card_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:focusable="true"
android:clickable="true"
android:foreground="?android:attr/selectableItemBackground">
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto">
<ImageView
android:id="#+id/flagcountry"
android:layout_width="0dp"
android:layout_height="match_parent"
app:layout_constraintDimensionRatio="W,55:100"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:layout_marginLeft="2dp"/>
<TextView
android:id="#+id/flagname"
android:layout_width="6dp"
android:layout_height="match_parent"
app:layout_constraintLeft_toRightOf="#id/flagcountry"
android:layout_centerVertical="true"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.cardview.widget.CardView>
</RelativeLayout>
under new kt file
package training.geography.triplerecyclerview
import android.provider.Settings.Global.getString
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ImageView
import android.widget.TextView
import androidx.cardview.widget.CardView
import androidx.recyclerview.widget.RecyclerView
class FlagAdapter(val flagcountrylist: List<FlagCard>,
val flagitemClickListener : View.OnClickListener
//val flagitemOnLongClickListener : View.OnLongClickListener
):
RecyclerView.Adapter<FlagAdapter.FlagViewHolder> () {
class FlagViewHolder(flagView: View) : RecyclerView.ViewHolder(flagView) {
val flagcardView = flagView.findViewById<CardView>(R.id.flag_card_view)
val flagcountry = flagView.findViewById<ImageView>(R.id.flagcountry)
val flagname = flagView.findViewById<TextView>(R.id.flagname)
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int):
FlagViewHolder {
val inflater = LayoutInflater.from(parent.context)
val viewItem = inflater.inflate(R.layout.item_flag, parent, false)
return FlagViewHolder(viewItem)
}
override fun onBindViewHolder(flagholder: FlagViewHolder, position: Int) {
//val flagcountry: String = flagcountrylist.FlagCard.flagimage[position]
//var flagimageList: List<String> = flagcountrylist.map { it.flagimage }
var flagsouthList: List<String> = flagcountrylist.map { it.flagsouth }
var iflagsouth = flagsouthList[position]
flagholder.flagname.text = iflagsouth
flagholder.flagcardView.tag = position
flagholder.flagcardView.setOnClickListener(flagitemClickListener)
//flagholder.flagcardView.setOnLongClickListener(itemOnLongClickListener)
when (position){
0 -> flagholder.flagcountry.setImageResource(R.drawable.afgcol)
1 -> flagholder.flagcountry.setImageResource(R.drawable.argsvk)
2 -> flagholder.flagcountry.setImageResource(R.drawable.armche)
3 -> flagholder.flagcountry.setImageResource(R.drawable.auttgo)
4 -> flagholder.flagcountry.setImageResource(R.drawable.azepry)
5 -> flagholder.flagcountry.setImageResource(R.drawable.bhrtur)
6 -> flagholder.flagcountry.setImageResource(R.drawable.bratls)
7 -> flagholder.flagcountry.setImageResource(R.drawable.bwasur)
8 -> flagholder.flagcountry.setImageResource(R.drawable.cafbtn)
9 -> flagholder.flagcountry.setImageResource(R.drawable.critun)
10 -> flagholder.flagcountry.setImageResource(R.drawable.pandza)
11 -> flagholder.flagcountry.setImageResource(R.drawable.persau)
12 -> flagholder.flagcountry.setImageResource(R.drawable.svnago)
13 -> flagholder.flagcountry.setImageResource(R.drawable.sweben)
14 -> flagholder.flagcountry.setImageResource(R.drawable.tcdgbr)
15 -> flagholder.flagcountry.setImageResource(R.drawable.thabol)
16 -> flagholder.flagcountry.setImageResource(R.drawable.tjkdeu)
17 -> flagholder.flagcountry.setImageResource(R.drawable.tkmbel)
18 -> flagholder.flagcountry.setImageResource(R.drawable.tzablz)
19 -> flagholder.flagcountry.setImageResource(R.drawable.ukrcmr)
20 -> flagholder.flagcountry.setImageResource(R.drawable.uryblr)
21 -> flagholder.flagcountry.setImageResource(R.drawable.venbgd)
22 -> flagholder.flagcountry.setImageResource(R.drawable.vnmbfa)
23 -> flagholder.flagcountry.setImageResource(R.drawable.yembih)
24 -> flagholder.flagcountry.setImageResource(R.drawable.zmbchl)
25 -> flagholder.flagcountry.setImageResource(R.drawable.zwealb)
}
//var iflagcard:String = imagelist[position]
//holder.flagcountry.setImageResource(iflagcard)
}
override fun getItemCount(): Int {
return flagcountrylist.size
}
}
---------------------------------------
//under new MainActivity file with function modified
// i don't know what to do with the variable
// flagtempup, i use it to set the string in
// iflagtrigramdown, and i have te warning variable not used...
package training.geography.triplerecyclerview
import android.nfc.Tag
import android.os.Bundle
import android.view.View
import android.view.View.OnClickListener
import android.view.animation.Animation
import android.view.animation.RotateAnimation
import android.widget.ImageView
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import androidx.cardview.widget.CardView
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import kotlinx.android.synthetic.main.item_flag.*
data class FlagCard(var flagtrigramup: String, var flagtrigramdown: String,
var flagimage: String, var flagsouth: String, var rotationpossible: Boolean=(true))
data class CountryCard(val countrytrigram: String, val description: String)
data class MapCard(var map_left_up: String,
var map_right_up: String,
var map_left_down: String,
var map_right_down: String,
var maps_img: String,
var mapnorth: String)
class MainActivity : AppCompatActivity(), OnClickListener {
var afg_col = FlagCard("col", "afg", "afgcol", "afg", true)
var arg_svk = FlagCard("arg", "svk", "argsvk", "svk", true)
var arm_che = FlagCard("che", "arm", "armche", "arm", true)
var aut_tgo = FlagCard("tgo", "aut", "auttgo", "aut", true)
var aze_pry = FlagCard("aze", "pry", "azepry", "pry", true)
var bhr_tur = FlagCard("tur", "bhr", "bhrtur", "bhr", true)
var bra_tls = FlagCard("tls", "bra", "bratls", "bra", true)
var bwa_sur = FlagCard("sur", "bwa", "bwasur", "bwa", true)
var caf_btn = FlagCard("btn", "caf", "cafbtn", "caf", true)
var cri_tun = FlagCard("cri", "tun", "critun", "tun", true)
var pan_dza = FlagCard("pan", "dza", "pandza", "dza", true)
var per_sau = FlagCard("per", "sau", "persau", "sau", true)
var svn_ago = FlagCard("svn", "ago", "svnago", "ago", true)
var swe_ben = FlagCard("swe", "ben", "sweben", "ben", true)
var tcd_gbr = FlagCard("tcd", "gbr", "tcdgbr", "gbr", true)
var tha_bol = FlagCard("tha", "bol", "thabol", "bol", true)
var tjk_deu = FlagCard("tjk", "deu", "tjkdeu", "deu", true)
var tkm_bel = FlagCard("tkm", "bel", "tkmbel", "bel", true)
var tza_blz = FlagCard("tza", "blz", "tzablz", "blz", true)
var ukr_cmr = FlagCard("ukr", "cmr", "ukrcmr", "cmr", true)
var ury_blr = FlagCard("ury", "blr", "uryblr", "blr", true)
var ven_bgd = FlagCard("ven", "bgd", "venbgd", "bgd", true)
var vnm_bfa = FlagCard("vnm", "bfa", "vnmbfa", "bfa", true)
var yem_bih = FlagCard("yem", "bih", "yembih", "bih", true)
var zmb_chl = FlagCard("zmb", "chl", "zmbchl", "chl", true)
var zwe_alb = FlagCard("zwe", "alb", "zwealb", "alb", true)
var afg = CountryCard("afg", "afg")
var ago = CountryCard("ago", "ago")
var alb = CountryCard("alb", "alb")
var arg = CountryCard("arg", "arg")
var arm = CountryCard("arm", "arm")
var aut = CountryCard("aut", "aut")
var aze = CountryCard("aze", "aze")
var bel = CountryCard("bel", "bel")
var bfa = CountryCard("bfa", "bfa")
var bhr = CountryCard("bhr", "bhr")
var bih = CountryCard("bih", "bih")
var blz = CountryCard("blz", "blz")
var bol = CountryCard("bol", "bol")
var bra = CountryCard("bra", "bra")
var btn = CountryCard("btn", "btn")
var bwa = CountryCard("bwa", "bwa")
var caf = CountryCard("caf", "caf")
var che = CountryCard("che", "che")
var chl = CountryCard("chl", "chl")
var cmr = CountryCard("cmr", "cmr")
var col = CountryCard("col", "col")
var cri = CountryCard("cri", "cri")
var deu = CountryCard("deu", "deu")
var gbr = CountryCard("gbr", "gbr")
var pan = CountryCard("pan", "pan")
var per = CountryCard("per", "per")
var pry = CountryCard("pry", "pry")
var sau = CountryCard("sau", "sau")
var sur = CountryCard("sur", "sur")
var svk = CountryCard("svk", "svk")
var svn = CountryCard("svn", "svn")
var swe = CountryCard("swe", "swe")
var tcd = CountryCard("tcd", "tcd")
var tgo = CountryCard("tgo", "tgo")
var tha = CountryCard("tha", "tha")
var tjk = CountryCard("tjk", "tjk")
var tkm = CountryCard("tkm", "tkm")
var tls = CountryCard("tls", "tls")
var tun = CountryCard("tun", "tun")
var tur = CountryCard("tur", "tur")
var tza = CountryCard("tza", "tza")
var ukr = CountryCard("ukr", "ukr")
var ury = CountryCard("ury", "ury")
var ven = CountryCard("ven", "ven")
var vnm = CountryCard("vnm", "vnm")
var yem = CountryCard("yem", "yem")
var zmb = CountryCard("zmb", "zmb")
var zwe = CountryCard("zwe", "zwe")
var arm_bol_gbr_ago = MapCard("arm", "bol", "gbr", "ago", "bol", "armbolgbrago")
var aze_bra_aut_ben = MapCard("aze", "bra", "aut", "ben", "bra", "azebraautben")
var bfa_blr_col_bgd = MapCard("bfa", "blr", "col", "bgd", "blr", "bfablrcolbgd")
var bwa_bel_bhr_chl = MapCard("bwa", "bel", "bhr", "chl", "bel", "bwabelbhrchl")
var caf_afg_alb_arg = MapCard("caf", "afg", "alb", "arg", "afg", "cafafgalbarg")
var che_tkm_tur_sur = MapCard("che", "tkm", "tur", "sur", "tkm", "chetkmtursur")
var cri_cmr_btn_bih = MapCard("cri", "cmr", "btn", "bih", "cmr", "cricmrbtnbih")
var sau_blz_deu_dza = MapCard("sau", "blz", "deu", "dza", "blz", "saublzdeudza")
var svn_tha_tcd_pry = MapCard("svn", "tha", "tcd", "pry", "tha", "svnthatcdpry")
var swe_tls_tgo_per = MapCard("swe", "tls", "tgo", "per", "tls", "swetlstgoper")
var tjk_pan_svk_tza = MapCard("tjk", "pan", "svk", "tza", "pan", "tjkpansvktza")
var ven_zwl_yem_ukr = MapCard("ven", "zwl", "yem", "ukr", "zwl", "venzwlyemukr")
var zmb_tur_ury_vnm = MapCard("zmb", "tur", "ury", "vnm", "tur", "zmbtururyvnm")
var flagcountrylist = listOf<FlagCard>(
afg_col,
arg_svk,
arm_che,
aut_tgo,
aze_pry,
bhr_tur,
bra_tls,
bwa_sur,
caf_btn,
cri_tun,
pan_dza,
per_sau,
svn_ago,
swe_ben,
tcd_gbr,
tha_bol,
tjk_deu,
tkm_bel,
tza_blz,
ukr_cmr,
ury_blr,
ven_bgd,
vnm_bfa,
yem_bih,
zmb_chl,
zwe_alb
)
val flagadapter = FlagAdapter(flagcountrylist, this)
var countryList = listOf<CountryCard>(
afg,
ago,
alb,
arg,
arm,
aut,
aze,
bel,
bfa,
bhr,
bih,
blz,
blz,
bol,
bra,
btn,
bwa,
caf,
che,
chl,
cmr,
col,
cri,
deu,
gbr,
pan,
per,
pry,
sau,
sur,
svk,
svn,
swe,
tcd,
tgo,
tha,
tjk,
tkm,
tls,
tun,
tur,
tza,
ukr,
ury,
ven,
vnm,
yem,
zmb,
zwe
)
val countryadapter = CountryAdapter(countryList)
var mapcountrylist = listOf<MapCard>(
arm_bol_gbr_ago,
aze_bra_aut_ben,
bfa_blr_col_bgd,
bwa_bel_bhr_chl,
caf_afg_alb_arg,
che_tkm_tur_sur,
cri_cmr_btn_bih,
sau_blz_deu_dza,
svn_tha_tcd_pry,
swe_tls_tgo_per,
tjk_pan_svk_tza,
ven_zwl_yem_ukr,
zmb_tur_ury_vnm
)
val mapadapter = MapAdapter(mapcountrylist)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val flagsrecyclerView = findViewById<RecyclerView>(R.id.flagsRecyclerView)
flagsrecyclerView.layoutManager = LinearLayoutManager(this, RecyclerView.HORIZONTAL, false)
flagsrecyclerView.adapter = flagadapter
val countryrecyclerView = findViewById<RecyclerView>(R.id.countriesRecyclerView)
countryrecyclerView.layoutManager = LinearLayoutManager(this, RecyclerView.HORIZONTAL, false)
countryrecyclerView.adapter = countryadapter
val maprecyclerView = findViewById<RecyclerView>(R.id.mapsRecyclerView)
maprecyclerView.layoutManager = LinearLayoutManager(this, RecyclerView.HORIZONTAL, false)
maprecyclerView.adapter = mapadapter
}
fun rotateFlagCard (flagCard: FlagCard, position: Int) : FlagCard {
var flagtrigramuplist: List<String> = flagcountrylist.map{it.flagtrigramup }
var iflagtrigramup : String = flagtrigramuplist[position]
var flagimagelist = flagcountrylist.map{it.flagimage}
var iflagimage = flagimagelist[position]
var flagsouthlist = flagcountrylist.map { it.flagsouth }
var iflagsouth = flagsouthlist[position]
var rotationpossiblelist : List<Boolean> = flagcountrylist.map{ it.rotationpossible }
var irotationpossible = rotationpossiblelist[position]
var iflagimageView = findViewById<ImageView>(R.id.flagcountry)
when (position) {
0 -> iflagimageView.setImageResource(R.drawable.afgcol)
1 -> iflagimageView.setImageResource(R.drawable.argsvk)
2 -> iflagimageView.setImageResource(R.drawable.armche)
3 -> iflagimageView.setImageResource(R.drawable.auttgo)
4 -> iflagimageView.setImageResource(R.drawable.azepry)
5 -> iflagimageView.setImageResource(R.drawable.bhrtur)
6 -> iflagimageView.setImageResource(R.drawable.bratls)
7 -> iflagimageView.setImageResource(R.drawable.bwasur)
8 -> iflagimageView.setImageResource(R.drawable.cafbtn)
9 -> iflagimageView.setImageResource(R.drawable.critun)
10 -> iflagimageView.setImageResource(R.drawable.pandza)
11 -> iflagimageView.setImageResource(R.drawable.persau)
12 -> iflagimageView.setImageResource(R.drawable.svnago)
13 -> iflagimageView.setImageResource(R.drawable.sweben)
14 -> iflagimageView.setImageResource(R.drawable.tcdgbr)
15 -> iflagimageView.setImageResource(R.drawable.thabol)
16 -> iflagimageView.setImageResource(R.drawable.tjkdeu)
17 -> iflagimageView.setImageResource(R.drawable.tkmbel)
18 -> iflagimageView.setImageResource(R.drawable.tzablz)
19 -> iflagimageView.setImageResource(R.drawable.ukrcmr)
20 -> iflagimageView.setImageResource(R.drawable.uryblr)
21 -> iflagimageView.setImageResource(R.drawable.venbgd)
22 -> iflagimageView.setImageResource(R.drawable.vnmbfa)
23 -> iflagimageView.setImageResource(R.drawable.yembih)
24 -> iflagimageView.setImageResource(R.drawable.zmbchl)
25 -> iflagimageView.setImageResource(R.drawable.zwealb)
else -> throw AssertionError()
}
if (irotationpossible)
{
iflagimageView.animate().apply {
rotationBy(180f)
duration = 1000L
start()
// permutation of values north south
var flagtrigramdownlist :List<String> = flagcountrylist.map{it.flagtrigramdown}
var iflagtrigramdown : String = flagtrigramdownlist[position]
var flagtempup: String = iflagtrigramup
var flagtempdown: String = iflagtrigramdown
iflagtrigramup = iflagsouth
//flagtempdown = flagtempup
iflagtrigramdown = flagtempup
var iflagCard = FlagCard( iflagtrigramup, iflagtrigramdown, iflagimage, iflagsouth, irotationpossible )
return iflagCard
}
} else {
return flagCard
//Toast.makeText(this, "flag already matched country", Toast.LENGTH_LONG).show()
}
}
override fun onClick(flagcardView: View) {
if (flagcardView.tag != null) {
val index = flagcardView.tag as Int
var flagsouthList: List<String> = flagcountrylist.map{it.flagsouth }
val flags = flagsouthList[index]
Toast.makeText(this, "country : ${flags}", Toast.LENGTH_LONG).show()
var flagcard:FlagCard = flagcountrylist[index]
rotateFlagCard (flagcard, index)
}
}
}

It looks like nobody is interested by what is possible to do with RecyclerViews...
I still have the problem that when an imageView is clicked, this is the one at left which is rotating ! i can't understand what happens, examination in debugger shows the variables are ok, the index is position and do not change...
I tried to apply rotate function to the cardView, same result !
I modified the code in the function and replace the flagCard by iflagCard if rotation was done (because two flags, one up, one down, and of course the FlagCard is different... )
Here the new code :
if (irotationpossible)
{
iflagcardView.animate().apply {
rotationBy(180f)
duration = 1000L
start()
// permutation of values north south
var flagtrigramdownlist :List<String> = flagcountrylist.map{it.flagtrigramdown}
var iflagtrigramdown : String = flagtrigramdownlist[position]
var flagtempup: String = iflagtrigramup
var flagtempdown: String = iflagtrigramdown
iflagtrigramup = iflagsouth
iflagsouth = flagtempup
iflagtrigramdown = flagtempup
var iflagCard = FlagCard( iflagtrigramup, iflagtrigramdown, iflagimage, iflagsouth, irotationpossible )
//flagcountrylist.toSet(position, iflagCard)
//abstract operator fun set(position: Int, iflagCard: FlagCard): FlagCard
flagcountrylist.removeAt(position)
flagcountrylist.add(position, iflagCard)
return iflagCard
}
} else {
return flagCard
//Toast.makeText(this, "flag already matched country", Toast.LENGTH_LONG).show()
}
my question is now about the set function for mutableListOf in Kotlin :
i tried to use " abstract operator fun set(index: Int, element: E): E "
but couldn't build because of abstract !
Is there any other way than my solution to remove then add at the same index ?
Is there any experimented developper curious about the strange rotation in that app ?
https://www.youtube.com/watch?v=d9o7fttLBxk
Why not the image with right index ?

How to create line graph dynamically like this image

Line Graph
I have 5 dynamic data which is giving +1 or -1 as result, if the result is +1 then graph direction is towards up and if the result is -1 then graph direction is towards downward.

Image in your question is not available to view but i can put a sample for how to draw a line chart in your android app easily.
First -as mentioned in comment- you can use MPAndroidChart. You can add it to your project like following:
implementation "com.github.PhilJay:MPAndroidChart:v3.0.3"
Here's a sample default line chart implementation which i use in my personal projects.
open class DefaultLineChart #JvmOverloads constructor(context: Context, attrs: AttributeSet? = null, defStyle: Int = 0)
: LineChart(context, attrs, defStyle) {
init {
setupChart()
}
private fun setupChart() {
// Init Description
val description = Description().apply {
isEnabled = false
}
setDescription(description)
// Init GridBackground
setGridBackgroundColor(android.R.color.white)
setDrawGridBackground(true)
// Init Borders
setDrawBorders(true)
setBorderColor(android.R.color.black)
setBorderWidth(1f)
// Init Other Properties
setPinchZoom(false)
isDoubleTapToZoomEnabled = false
isDragEnabled = true
setNoDataText(context.getString(R.string.info_text_no_content))
setScaleEnabled(true)
// Init Legend
val legend = legend.apply {
isEnabled = false
}
// Init xAxis
val xAxis = xAxis.apply {
isEnabled = true
setCenterAxisLabels(false)
gridColor = android.R.color.white
setAvoidFirstLastClipping(false)
setDrawLimitLinesBehindData(true)
position = XAxis.XAxisPosition.BOTTOM
}
// Init leftAxis
val leftAxis = axisLeft.apply {
axisMinimum = 0f
setDrawAxisLine(false)
setDrawZeroLine(true)
setDrawGridLines(true)
gridColor = android.R.color.black
axisLineColor = android.R.color.black
}
val rightAxis = axisRight.apply {
isEnabled = false
}
}
fun setChartTitle(title: String) {
val description = Description().apply {
text = title
isEnabled = true
}
setDescription(description)
}
}
You can add it to your xml layout like below:
<path_to_your_class.DefaultLineChart
android:layout_width="match_parent"
android:layout_height="400dp"
android:layout_marginTop="16dp"/>
Finally you can draw your chart like following code:
fun bindDefaultLineChart(chartView: LineChart,
marketValues: List<MarketVal>?,
label: String?) {
if (marketValues == null) {
return
}
val yValues = ArrayList<Entry>()
var maxCount: Long = 0
for (marketValue in marketValues) {
val entry = Entry(marketValue.dateTime.toFloat(),
marketValue.transactionNumber.toFloat())
yValues.add(entry)
if (marketValue.transactionNumber > maxCount) {
maxCount = marketValue.transactionNumber.toLong()
}
}
val xAxis = chartView.xAxis
val xAxisFormatter = ChartValueDateFormatter(Constants.DEFAULT_DATE_FORMAT)
xAxis.valueFormatter = xAxisFormatter
chartView.axisLeft.apply {
axisMaximum = (maxCount + MAX_CHAR_Y_AXIS_ADDITION).toFloat()
valueFormatter = NonFloatValueFormatter()
}
val dataSet = LineDataSet(yValues, label).apply {
axisDependency = YAxis.AxisDependency.LEFT
color = ContextCompat.getColor(chartView.context, R.color.colorAccent)
formLineWidth = 2f
setDrawIcons(true)
setDrawValues(false)
}
val lineData = LineData(dataSet)
chartView.data = lineData
}
}
You can find example implementation from here.

Android Studio Convert Java To Kotlin 2 errors

After Convert Java File to Kotlin File, gives me two errors in same line: In code below show variables and function with error
lateinit var ncArr: Array<ImageButton>
lateinit var xBitmap: Bitmap
lateinit var oBitmap: Bitmap
lateinit var intArr: IntArray
lateinit var btnStartGame: Button
lateinit var btnMenu: Button
var stop: Boolean = false
var gameMode: Int = 0
var umove: Int = 0
override fun onCreate(savedInstanceState: Bundle?) {
super.onStart()
setContentView(R.layout.activity_game)
ncArr = arrayOfNulls(9)
ncArr[0] = findViewById(R.id.nc0) as ImageButton
ncArr[1] = findViewById(R.id.nc1) as ImageButton
ncArr[2] = findViewById(R.id.nc2) as ImageButton
ncArr[3] = findViewById(R.id.nc3) as ImageButton
ncArr[4] = findViewById(R.id.nc4) as ImageButton
ncArr[5] = findViewById(R.id.nc5) as ImageButton
ncArr[6] = findViewById(R.id.nc6) as ImageButton
ncArr[7] = findViewById(R.id.nc7) as ImageButton
ncArr[8] = findViewById(R.id.nc8) as ImageButton
ncArr[0].setOnClickListener(this)
ncArr[1].setOnClickListener(this)
ncArr[2].setOnClickListener(this)
ncArr[3].setOnClickListener(this)
ncArr[4].setOnClickListener(this)
ncArr[5].setOnClickListener(this)
ncArr[6].setOnClickListener(this)
ncArr[7].setOnClickListener(this)
ncArr[8].setOnClickListener(this)
xBitmap = BitmapFactory.decodeResource(resources, R.drawable.x)
oBitmap = BitmapFactory.decodeResource(resources, R.drawable.o)
intArr = IntArray(9)
for (i in 0..8) {
intArr[i] = 0
}
btnMenu = findViewById(R.id.btnMenu) as Button
btnStartGame = findViewById(R.id.btnStartGame) as Button
btnMenu.setOnClickListener(this)
btnStartGame.setOnClickListener(this)
stop = false
gameMode = intent.getIntExtra("game_mode", 1)
umove = 1
}
in line ncArr = arrayOfNulls(9)
There are errors:
I trying to fix this problem but i don't have more ideas...
Any sollution?
thanks in advance

ncArr = arrayOfNulls(9)
The type of ncArr will be Array<ImageButton?>
ncArr[0] = findViewById(R.id.nc0) as ImageButton
You are using unsafe cast operator as, because the cast operator throws an exception if the cast is not possible. Thus, we call it unsafe. What happens if
findViewById(R.id.nc0) as ImageButton
return null, then null cannot assign to ImageButton, it will throw an exception and make your app crash.
To avoid the above error you can use
ncArr[0] = findViewById(R.id.nc0) as ImageButton?
or using safe cast operator as?
ncArr[0] = findViewById(R.id.nc0) as? ImageButton
Remember apply for ncArr[0] to ncArr[8].
Update: Based on your request, you can use this solution:
lateinit var ncArr: Array<ImageButton>
lateinit var xBitmap: Bitmap
lateinit var oBitmap: Bitmap
lateinit var intArr: IntArray
lateinit var btnStartGame: Button
lateinit var btnMenu: Button
var stop: Boolean = false
var gameMode: Int = 0
var umove: Int = 0
override fun onCreate(savedInstanceState: Bundle?) {
super.onStart()
setContentView(R.layout.activity_game)
ncArr = arrayOf(
findViewById<ImageButton>(R.id.nc0).apply{setOnClickListener(this#GameActivity)},
findViewById<ImageButton>(R.id.nc1).apply{setOnClickListener(this#GameActivity)},
findViewById<ImageButton>(R.id.nc2).apply{setOnClickListener(this#GameActivity)},
findViewById<ImageButton>(R.id.nc3).apply{setOnClickListener(this#GameActivity)},
findViewById<ImageButton>(R.id.nc4).apply{setOnClickListener(this#GameActivity)},
findViewById<ImageButton>(R.id.nc5).apply{setOnClickListener(this#GameActivity)},
findViewById<ImageButton>(R.id.nc6).apply{setOnClickListener(this#GameActivity)},
findViewById<ImageButton>(R.id.nc7).apply{setOnClickListener(this#GameActivity)},
findViewById<ImageButton>(R.id.nc8).apply{setOnClickListener(this#GameActivity)}
)
xBitmap = BitmapFactory.decodeResource(resources, R.drawable.x)
oBitmap = BitmapFactory.decodeResource(resources, R.drawable.o)
// Your code here
...
}

You trying to put Nullable array into NonNull. You may declare intArr as Array<ImageButton?> and everything will work.