Develop Reference

Unresolved reference to constraintLayout variable in Kotlin code in android app

I am following this tutorial to create an android app with space animation stuff. In the step titled "Transition Manager" you're instructed to add the following code to your MainActivity.kt file:
`
constraintSet1.clone(constraintLayout) //1
constraintSet2.clone(this, R.layout.activity_main) //2
departButton.setOnClickListener { //3
//apply the transition
TransitionManager.beginDelayedTransition(constraintLayout) //4
val constraint = if (!isOffscreen) constraintSet1 else constraintSet2
isOffscreen = !isOffscreen
constraint.applyTo(constraintLayout) //5
}
`
When this code is added the variable "constraintLayout" throws up an unresolved reference error
I think constraintLayout is supposed to be pointing to something in the xml and something is failing to make that happen, I just don't know what.
The kotlin code after adding the above block is:
`
package com.raywenderlich.android.razegalactic
import android.os.Bundle
import android.support.constraint.*
import android.support.v7.app.AppCompatActivity
import android.transition.TransitionManager
import kotlinx.android.synthetic.main.keyframe1.*
/**
* Main Screen
*/
class MainActivity : AppCompatActivity() {
private val constraintSet1 = ConstraintSet()
private val constraintSet2 = ConstraintSet()
private var isOffscreen = true
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.keyframe1)
switch1.setOnCheckedChangeListener { _, isChecked ->
switch1.setText(if (isChecked) R.string.round_trip else R.string.one_way)
constraintSet1.clone(constraintLayout) //1
constraintSet2.clone(this, R.layout.activity_main) //2
departButton.setOnClickListener { //3
//apply the transition
TransitionManager.beginDelayedTransition(constraintLayout) //4
val constraint = if (!isOffscreen) constraintSet1 else constraintSet2
isOffscreen = !isOffscreen
constraint.applyTo(constraintLayout) //5
}
}
}
}
`
The main xml is as follows:
`
<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:id="#+id/ConstraintLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center_horizontal"
android:orientation="vertical"
tools:context=".MainActivity">
<ImageView
android:id="#+id/flightsIcon"
android:layout_width="30dp"
android:layout_height="30dp"
android:src="#drawable/rocket_icon"
app:layout_constraintBottom_toBottomOf="#+id/spaceStationIcon"
app:layout_constraintEnd_toStartOf="#+id/roverIcon"
app:layout_constraintStart_toEndOf="#+id/spaceStationIcon"
app:layout_constraintTop_toTopOf="#+id/spaceStationIcon" />
<ImageView
android:id="#+id/spaceStationIcon"
android:layout_width="30dp"
android:layout_height="30dp"
android:layout_marginTop="15dp"
android:src="#drawable/space_station_icon"
app:layout_constraintEnd_toStartOf="#+id/flightsIcon"
app:layout_constraintHorizontal_chainStyle="spread"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ImageView
android:id="#+id/roverIcon"
android:layout_width="30dp"
android:layout_height="30dp"
android:src="#drawable/rover_icon"
app:layout_constraintBottom_toBottomOf="#+id/flightsIcon"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/flightsIcon"
app:layout_constraintTop_toTopOf="#+id/flightsIcon" />
<TextView
android:id="#+id/spaceStationLabel"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="15dp"
android:text="#string/space_stations"
app:layout_constraintEnd_toEndOf="#+id/spaceStationIcon"
app:layout_constraintStart_toStartOf="#+id/spaceStationIcon"
app:layout_constraintTop_toBottomOf="#+id/spaceStationIcon" />
<TextView
android:id="#+id/textView1"
android:layout_width="124dp"
android:layout_height="98dp"
android:layout_marginEnd="40dp"
android:background="#color/colorPrimary"
android:gravity="center"
android:paddingEnd="20dp"
android:text="#string/dca"
android:textColor="#android:color/white"
app:layout_constraintBottom_toBottomOf="#+id/doubleArrowsIcon"
app:layout_constraintEnd_toEndOf="#+id/doubleArrowsIcon"
app:layout_constraintTop_toTopOf="#+id/doubleArrowsIcon" />
<TextView
android:id="#+id/roverLabel"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="15dp"
android:text="#string/rovers"
app:layout_constraintEnd_toEndOf="#+id/roverIcon"
app:layout_constraintStart_toStartOf="#+id/roverIcon"
app:layout_constraintTop_toBottomOf="#+id/roverIcon" />
<TextView
android:id="#+id/textView2"
android:layout_width="124dp"
android:layout_height="98dp"
android:layout_marginStart="40dp"
android:background="#color/colorPrimary"
android:gravity="center"
android:paddingStart="20dp"
android:text="#string/mars"
android:textColor="#android:color/white"
app:layout_constraintBottom_toBottomOf="#+id/doubleArrowsIcon"
app:layout_constraintStart_toStartOf="#+id/doubleArrowsIcon"
app:layout_constraintTop_toTopOf="#+id/doubleArrowsIcon" />
<TextView
android:id="#+id/flightsLabel"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="15dp"
android:text="#string/flights"
app:layout_constraintEnd_toEndOf="#+id/flightsIcon"
app:layout_constraintStart_toStartOf="#+id/flightsIcon"
app:layout_constraintTop_toBottomOf="#+id/flightsIcon" />
<ImageView
android:id="#+id/doubleArrowsIcon"
android:layout_width="60dp"
android:layout_height="60dp"
android:layout_marginBottom="40dp"
android:src="#drawable/double_arrows"
app:layout_constraintBottom_toTopOf="#+id/guideline1"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<Switch
android:id="#+id/switch1"
android:layout_width="160dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="200dp"
android:background="#color/colorAccent"
android:checked="false"
android:padding="8dp"
android:switchPadding="24dp"
android:text="#string/one_way"
android:textColor="#android:color/white"
app:layout_constraintStart_toStartOf="#+id/guideline2"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:background="#color/colorAccent"
android:padding="8dp"
android:text="#string/traveller"
android:textColor="#android:color/white"
app:layout_constraintStart_toStartOf="#+id/guideline2"
app:layout_constraintTop_toBottomOf="#+id/switch1" />
<ImageView
android:id="#+id/rocketIcon"
android:layout_width="30dp"
android:layout_height="30dp"
android:layout_marginEnd="8dp"
android:src="#drawable/rocket_icon"
app:layout_constraintCircle="#id/galaxyIcon"
app:layout_constraintCircleAngle="270"
app:layout_constraintCircleRadius="100dp" />
<ImageView
android:id="#+id/galaxyIcon"
android:layout_width="90dp"
android:layout_height="90dp"
android:src="#drawable/galaxy"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="#+id/guideline1"
app:layout_constraintVertical_bias="0.495" />
<Button
android:id="#+id/departButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/depart"
android:textColor="#android:color/white"
app:backgroundTint="#color/colorPrimary"
app:layout_constraintBottom_toBottomOf="parent"
tools:layout_editor_absoluteX="158dp" />
<android.support.constraint.Guideline
android:id="#+id/guideline1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_begin="0dp" />
<android.support.constraint.Guideline
android:id="#+id/guideline2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintGuide_percent="1" />
</android.support.constraint.ConstraintLayout>
`
can anyone tell me what I might be missing or how this can be fixed?
Thanks in advance.

You're suppose to reference a view from the xml before you can use it.
Do this, also if the name of the layout the MainActivity is suppose to use is main.xml, it should be the one your setContentView use not some other layout.
lateinit var cosntraintLayout: ConstraintLayout
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.main) // <- main.xml
cosntraintLayout = findViewById<ConstraintLayout>(R.id.ConstraintLayout) // <- add this line
...
...
}
switch1 and departButton will also throw the same error, but I'll leave it for you to figure it out based on the code I provided.

Scroll to top of RecyclerView using setOnClickListener

I have this home button in top bar:
val activity: ImageButton =findViewById(R.id.activity)
activity.setOnClickListener{
startActivity(Intent(this, ActivitySearch::class.java))
}
Instead of going to a new page, I want to be able to just put a "to top" intent, I have tried to replace:
startActivity(Intent(this, ActivitySearch::class.java))
with
mRecyclerView.smoothScrollToPosition(0);
But this does not work, any ideas? I do have a RecyclerView in use so half way down, I want to be able to click the above button and it goes straight to the top.
Total code:
private val apiService by lazy {
ApiClient.create()
}
private var taskData : ArrayList<TaskResponse> = arrayListOf();
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val activity: ImageButton =findViewById(R.id.activity)
activity.setOnClickListener{
startActivity(Intent(this, ActivitySearch::class.java))
}
val searchbutton:ImageButton=findViewById(R.id.searchbutton)
searchbutton.setOnClickListener{
startActivity(Intent(this, ActivitySearch::class.java))
}
val saves:ImageButton=findViewById(R.id.saves)
saves.setOnClickListener{
startActivity(Intent(this, ActivitySaves::class.java))
}
val settings:ImageButton=findViewById(R.id.settings)
settings.setOnClickListener{
startActivity(Intent(this, ActivitySettings::class.java))
}
loadData();
}
private fun loadData(){
var data = apiService.getMainData();
data.enqueue(object : Callback<ArrayList<TaskResponse>> {
override fun onResponse(
call: Call<ArrayList<TaskResponse>>,
response: Response<ArrayList<TaskResponse>>
) {
if (response.code() == 200) {
taskData = response.body()!!;
displaydata();
}
}
override fun onFailure(call: Call<ArrayList<TaskResponse>>, t: Throwable) {
Log.d("-----------------", t.toString())
}
})
}
private fun displaydata(){
var recyclerView = findViewById<RecyclerView>(R.id.mainList);
var adapter = TaskAdapter(this, taskData);
recyclerView.layoutManager = LinearLayoutManager(this)
recyclerView.adapter = adapter
val swipeRefreshLayout: SwipeRefreshLayout = findViewById(R.id.swipeRefreshLayout)
// load data on swipe refresh.
swipeRefreshLayout.setOnRefreshListener { loadData() }
// Disable the refreshing after data load
swipeRefreshLayout.isRefreshing = false
}
And what i'm using for activity page:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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=".MainActivity">
<View
android:id="#+id/view"
android:layout_width="match_parent"
android:layout_height="0.1dp"
android:background="#6A6A6A"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/searchbutton"
app:layout_constraintVertical_bias="0.01" />
<TextView
android:id="#+id/textView"
android:layout_width="wrap_content"
android:layout_height="46dp"
android:gravity="center"
android:text="#string/w2d"
android:textColor="#color/black"
android:textSize="25sp"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.047"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.01" />
<ImageButton
android:id="#+id/activity"
android:layout_width="45dp"
android:layout_height="46dp"
android:layout_gravity="center"
android:layout_marginEnd="10dp"
android:layout_marginRight="10dp"
android:background="#FFFFFF"
android:contentDescription="#string/activities"
android:src="#drawable/ic_home"
android:tint="#00B0F0"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.107"
app:layout_constraintStart_toEndOf="#+id/textView"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.01" />
<ImageButton
android:id="#+id/searchbutton"
android:layout_width="48dp"
android:layout_height="48dp"
android:layout_gravity="center"
android:layout_marginEnd="10dp"
android:layout_marginRight="10dp"
android:background="#FFFFFF"
android:contentDescription="#string/activities"
android:src="#drawable/ic_search"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.154"
app:layout_constraintStart_toEndOf="#+id/activity"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.01" />
<ImageButton
android:id="#+id/saves"
android:layout_width="48dp"
android:layout_height="48dp"
android:layout_gravity="center"
android:layout_marginEnd="10dp"
android:layout_marginRight="10dp"
android:background="#FFFFFF"
android:contentDescription="#string/activities"
android:src="#drawable/ic_saves"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.242"
app:layout_constraintStart_toEndOf="#+id/searchbutton"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.01" />
<ImageButton
android:id="#+id/settings"
android:layout_width="48dp"
android:layout_height="48dp"
android:layout_gravity="center"
android:layout_marginEnd="10dp"
android:layout_marginRight="10dp"
android:background="#FFFFFF"
android:contentDescription="#string/activities"
android:src="#drawable/ic_setting"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.673"
app:layout_constraintStart_toEndOf="#+id/saves"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.01" />
<androidx.swiperefreshlayout.widget.SwipeRefreshLayout
android:id="#+id/swipeRefreshLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#00FFFFFF"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="#+id/view"
app:layout_constraintHorizontal_bias="0.0">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/mainList"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#F0F2F5"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toBottomOf="#+id/view"
app:layout_constraintVertical_bias="0"
tools:layout_editor_absoluteX="0dp" />
</androidx.swiperefreshlayout.widget.SwipeRefreshLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

This should work for going to the top of the recyclerView.
mRecyclerView.smoothScrollToPosition(0);
or
mRecyclerView.scrollToPosition(0);
When your list changes in recyclerView adapter, you should use that code. Make sure other parts of the code. This should work.

Using a comments answer from #cactustictacs, I edited my code to this and it worked:
val activity: ImageButton =findViewById(R.id.activity)
val mRecyclerView = findViewById<RecyclerView>(R.id.mainList)
activity.setOnClickListener{
mRecyclerView.smoothScrollToPosition(0)
}

Comparing drawables imageButtons in android

I have 6 image buttons with drawables, I'm trying to compare them using getDrawable().
Here's my xml code
'''
<
?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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=".TicTacToe">
<ImageButton
android:id="#+id/imageButton1"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginStart="25dp"
android:layout_marginTop="147dp"
android:layout_marginEnd="5dp"
android:layout_marginBottom="14dp"
android:onClick="change"
app:layout_constraintBottom_toTopOf="#+id/imageButton2"
app:layout_constraintEnd_toStartOf="#+id/imageButton01"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/blank" />
<ImageButton
android:id="#+id/imageButton01"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginTop="147dp"
android:layout_marginEnd="5dp"
android:layout_marginBottom="14dp"
android:onClick="change"
app:layout_constraintBottom_toTopOf="#+id/imageButton02"
app:layout_constraintEnd_toStartOf="#+id/imageButton001"
app:layout_constraintStart_toEndOf="#+id/imageButton1"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/blank" />
<ImageButton
android:id="#+id/imageButton2"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginStart="24dp"
android:layout_marginEnd="6dp"
android:layout_marginBottom="10dp"
android:onClick="change"
app:layout_constraintBottom_toTopOf="#+id/imageButton3"
app:layout_constraintEnd_toStartOf="#+id/imageButton02"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/imageButton1"
app:srcCompat="#drawable/blank" />
<ImageButton
android:id="#+id/imageButton001"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginTop="148dp"
android:layout_marginEnd="16dp"
android:layout_marginBottom="13dp"
android:onClick="change"
app:layout_constraintBottom_toTopOf="#+id/imageButton002"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/imageButton01"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/blank" />
<ImageButton
android:id="#+id/imageButton02"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginEnd="7dp"
android:layout_marginBottom="10dp"
android:onClick="change"
app:layout_constraintBottom_toTopOf="#+id/imageButton03"
app:layout_constraintEnd_toStartOf="#+id/imageButton002"
app:layout_constraintStart_toEndOf="#+id/imageButton2"
app:layout_constraintTop_toBottomOf="#+id/imageButton01"
app:srcCompat="#drawable/blank" />
<ImageButton
android:id="#+id/imageButton002"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginEnd="14dp"
android:layout_marginBottom="10dp"
android:onClick="change"
app:layout_constraintBottom_toTopOf="#+id/imageButton003"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/imageButton02"
app:layout_constraintTop_toBottomOf="#+id/imageButton001"
app:srcCompat="#drawable/blank" />
<ImageButton
android:id="#+id/imageButton3"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginStart="24dp"
android:layout_marginEnd="6dp"
android:layout_marginBottom="200dp"
android:onClick="change"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="#+id/imageButton03"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/imageButton2"
app:srcCompat="#drawable/blank" />
<ImageButton
android:id="#+id/imageButton03"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginEnd="7dp"
android:layout_marginBottom="200dp"
android:onClick="change"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="#+id/imageButton003"
app:layout_constraintStart_toEndOf="#+id/imageButton3"
app:layout_constraintTop_toBottomOf="#+id/imageButton02"
app:srcCompat="#drawable/blank" />
<ImageButton
android:id="#+id/imageButton003"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginEnd="14dp"
android:layout_marginBottom="200dp"
android:onClick="change"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/imageButton03"
app:layout_constraintTop_toBottomOf="#+id/imageButton002"
app:srcCompat="#drawable/blank" />
</androidx.constraintlayout.widget.ConstraintLayout
'''
kotlin code
'''
class TicTacToe : AppCompatActivity() {
var spot1: ImageButton? =null
var spot01: ImageButton? =null
var spot001: ImageButton? =null
var spot2: ImageButton? =null
var spot02: ImageButton? =null
var spot002: ImageButton? =null
var spot3: ImageButton? =null
var spot03: ImageButton? =null
var spot003: ImageButton? =null
override fun onCreate(savedInstanceState: Bundle?)
{
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_tic_tac_toe)
spot1 = findViewById<ImageButton>(R.id.imageButton1)
spot01 = findViewById<ImageButton>(R.id.imageButton01)
spot001 = findViewById<ImageButton>(R.id.imageButton001)
spot2 = findViewById<ImageButton>(R.id.imageButton2)
spot02 = findViewById<ImageButton>(R.id.imageButton02)
spot002 = findViewById<ImageButton>(R.id.imageButton002)
spot3 = findViewById<ImageButton>(R.id.imageButton3)
spot03 = findViewById<ImageButton>(R.id.imageButton03)
spot003 = findViewById<ImageButton>(R.id.imageButton003)
}
val photos: IntArray= intArrayOf(R.drawable.x, R.drawable.o, R.drawable.blank)
var turn = 1
var winState = false
fun change(view: View){
var spot = findViewById<ImageButton>(view.getId()) //as Button
if(turn == 1) {
spot.setImageResource(photos[0])
turn = turn * -1
}
else{
spot.setImageResource(photos[1])
turn = turn * -1
}
if(spot1?.getDrawable() == spot01?.getDrawable() &&
spot1?.getDrawable() == spot001?.getDrawable() &&
spot1?.getDrawable() != photos[2].toDrawable())
{
winState = true;
Toast.makeText(getApplicationContext(),"Winner",Toast.LENGTH_SHORT).show();
}
}
}
'''

Drawable is an Object, and as such needs to be compared using the equals() method. Anyway, I am not sure that it will work either, because I am not sure of how a Drawable implements that method, so it might not be suitable for your case.
Also, you are using your view to check the state of your business logic, and that's not ideal at all. The best solution would be to have a Map or a matrix (let's say, an array with a dimension of [3][3]), where you store the actual value of the single spots, and then you reconcile the drawables with the values in the matrix.
I know that this would affect everything in your code and you have to heavely change it, so a quickier solution could be to use android:tag on your ImageButtons. You can specify any Object on it, so you could also use and Integer and compare it, always using the equals() method. This means you can rely on the tag for your logic.

Two-Way Data Binding with a LiveData object of modal class

I'm trying to create a Two-Way Data binding connection with a LiveData object of a modal class. But when I tries to read the values of user it turns out to be null. Here is my code -
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
val viewModal: MainActivityViewModal = ViewModelProvider(
this,
MainActivityViewModalFactory()
).get(MainActivityViewModal::class.java)
val binding = DataBindingUtil.setContentView<ActivityMainBinding>(
this,
R.layout.activity_main
).apply {
this.lifecycleOwner = this#MainActivity
this.viewModal = viewModal
}
}}
Here is the Layout file -
<data>
<variable
name="viewModal"
type="com.weaponx.databindingexample.MainActivityViewModal" />
</data>
<androidx.constraintlayout.widget.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=".MainActivity">
<ImageView
android:id="#+id/ivLogo"
android:layout_width="100dp"
android:layout_height="100dp"
android:contentDescription="#string/logo"
android:tint="#000000"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#android:drawable/ic_menu_myplaces" />
<androidx.constraintlayout.widget.ConstraintLayout
android:id="#+id/clBody"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/ivLogo">
<androidx.constraintlayout.widget.Guideline
android:id="#+id/guideline1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_percent="0.10" />
<com.google.android.material.textfield.TextInputLayout
android:id="#+id/tilUserName"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:background="#drawable/edit_text_bg"
android:hint="#string/user_name"
android:padding="5dp"
app:layout_constraintEnd_toStartOf="#id/guideline2"
app:layout_constraintStart_toEndOf="#id/guideline1"
app:layout_constraintTop_toTopOf="parent">
<com.google.android.material.textfield.TextInputEditText
android:id="#+id/tietUserName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#null"
android:inputType="text"
android:text="#={viewModal.user.userName}" />
</com.google.android.material.textfield.TextInputLayout>
<com.google.android.material.textfield.TextInputLayout
android:id="#+id/tilPassword"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"
android:background="#drawable/edit_text_bg"
android:hint="#string/password"
android:padding="5dp"
app:layout_constraintEnd_toStartOf="#id/guideline2"
app:layout_constraintStart_toEndOf="#id/guideline1"
app:layout_constraintTop_toBottomOf="#id/tilUserName">
<com.google.android.material.textfield.TextInputEditText
android:id="#+id/tietPassword"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#null"
android:inputType="textPassword"
android:text="#={viewModal.user.password}" />
</com.google.android.material.textfield.TextInputLayout>
<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="80dp"
android:background="#drawable/button_bg"
android:text="#string/login"
android:onClick="#{() -> viewModal.login()}"
android:textAllCaps="false"
android:textColor="#android:color/white"
android:textSize="18sp"
app:layout_constraintEnd_toStartOf="#id/guideline2"
app:layout_constraintStart_toEndOf="#id/guideline1"
app:layout_constraintTop_toBottomOf="#id/tilPassword" />
<androidx.constraintlayout.widget.Guideline
android:id="#+id/guideline2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_percent="0.90" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
Here is the ViewModal
class MainActivityViewModal : ViewModel() {
var user = MutableLiveData<User>()
fun login() {
println("Login Success ${user.value}")
}}
And here is the Modal Class
class User() {
var userName: String = ""
var password: String = ""
override fun toString(): String {
return "User(userName='$userName', password='$password')"
}}
Please tell me any solution or a good way around to this problem

In the MainActivityViewModal define user as just User type rather as MutableLiveData.

Android gridview in fragment can't scrolling

I have one page called products. When page is loaded it shows productsfragment. This fragment has one RecyclerView which doesn't have any problem. On selecting a product a new fragment opens up and shows the list of product prices fragment. This fragment has one RecyclerView and the scrolling here doesn't works.
I tried gridview and cardview but they too are not scrolling. I tried gridview in scroll view or nested scroll view, they are also not scrolling.
here is my fragment with RecyclerView which is not scrolling
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/sorderfragment_step1_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".Activities.OrderSelect.Fragments.ProductSingleOrder.SOrderFragment_Step1">
<android.support.v7.widget.RecyclerView
android:id="#+id/gvProductPrices"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
and its my RecyclerView item view
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="200dp"
android:layout_height="200dp"
android:gravity="center"
android:maxHeight="200dp"
android:minHeight="200dp"
android:background="#layout/border2"
android:padding="0dp"
android:orientation="vertical">
<TextView
android:id="#+id/txtPriceName"
android:layout_width="match_parent"
android:layout_height="100dp"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="8dp"
android:gravity="center"
android:text="Kucuk Boy Whopper"
android:textSize="30sp"
android:textStyle="bold"
app:layout_constraintBottom_toTopOf="#+id/constraintLayout4"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<android.support.constraint.ConstraintLayout
android:id="#+id/constraintLayout4"
android:layout_width="match_parent"
android:layout_height="1dp"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="0dp"
android:background="#000000"
app:layout_constraintBottom_toTopOf="#+id/txtPrice"
app:layout_constraintEnd_toEndOf="parent">
</android.support.constraint.ConstraintLayout>
<TextView
android:id="#+id/txtPrice"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="4dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:gravity="center"
android:text="14.99"
android:textColor="#000000"
android:textSize="24sp"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent" />
</LinearLayout>
and my adapter
class PriceAdapter(val priceList : List<ProductPrice>,
val context: Context) : RecyclerView.Adapter<ViewHolder>() {
override fun onCreateViewHolder(p0: ViewGroup, p1: Int): ViewHolder {
return ViewHolder(LayoutInflater.from(context).inflate(R.layout.gv_product_prices, p0, false))
}
override fun getItemCount(): Int {
return priceList.size
}
override fun onBindViewHolder(p0: ViewHolder, p1: Int) {
val price = priceList[p1]
p0.txtPriceName.text = price.getDescription()
p0.txtPriceName.isAllCaps = true
p0.txtPrice.text = BaseHelper.getNumericStr(price.getPrice())
}
}
class ViewHolder (view: View) : RecyclerView.ViewHolder(view) {
val txtPriceName = view.txtPriceName!!
val txtPrice = view.txtPrice!!
}
and my fragment code
class SOrderFragment_Step1 : Fragment() {
private var _priceRepository = ProductPriceRepository(OrderRepository.orderSelect!!)
private var priceAdapter: PriceAdapter? = null
private var prices: List<ProductPrice>? = null
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
return inflater.inflate(R.layout.fragment_sorder_step1, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
configurePrices()
}
private fun configurePrices() {
prices = _priceRepository.getPriceByProductId(OrderRepository.currentProduct!!.getId())
gvProductPrices.layoutManager = GridLayoutManager(OrderRepository.orderSelect!!, 2)
gvProductPrices.adapter = PriceAdapter(prices!!, this, OrderRepository.orderSelect!!)
}
fun priceSelect(price: ProductPrice) {
Toast.makeText(OrderRepository.orderSelect!!, price.getDescription(), Toast.LENGTH_LONG).show()
}
}
and also fragment change like this
val manager = this.fragmentManager!!.beginTransaction()
manager.setCustomAnimations(android.R.anim.fade_in, android.R.anim.fade_out)
manager.replace(R.id.fragmentProductSteps, SOrderFragment_Step1(), "detailFragment").commit()
and fragment base activity xml
<?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"
android:id="#+id/order_select_layout"
tools:context=".OrderSelect">
<GridView
android:id="#+id/gvProductGroups"
android:layout_width="165dp"
android:layout_height="0dp"
android:layout_marginTop="16dp"
android:scrollbars="none"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/linearLayout" />
<LinearLayout
android:id="#+id/linearLayout"
android:layout_width="0dp"
android:layout_height="225dp"
android:orientation="horizontal"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<android.support.constraint.ConstraintLayout
android:layout_width="0dip"
android:layout_height="match_parent"
android:layout_weight="7">
<include
layout="#layout/activity_advertise_partition"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
</LinearLayout>
<LinearLayout
android:id="#+id/orderProductLayout"
android:layout_width="0dp"
android:layout_height="83dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:background="#layout/gv_order_products_border"
android:orientation="vertical"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="#+id/btnCancelCurrentOrder2"
app:layout_constraintStart_toEndOf="#+id/gvProductGroups">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginLeft="20dp"
android:layout_marginTop="5dp"
android:id="#+id/paymentView"
android:layout_marginRight="5dp"
android:layout_marginBottom="5dp"
android:layout_weight="1">
<TextView
android:id="#+id/txtTotalL"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="TOPLAM :"
android:textColor="#bc3030"
android:textSize="24sp"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/txtPriceL"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginEnd="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="-1dp"
android:layout_weight="1"
android:gravity="left|center"
android:text="₺ 0.00"
android:textColor="#000000"
android:textSize="24sp"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="#+id/imgOrderButton"
app:layout_constraintStart_toEndOf="#+id/txtTotalL"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.0" />
<Button
android:id="#+id/imgOrderButton"
android:layout_width="175dp"
android:layout_height="0dp"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="8dp"
android:background="#15912e"
android:padding="15sp"
android:text="Sepeti Goster"
android:textColor="#FFFFFF"
android:textSize="18sp"
android:textStyle="bold"
android:visibility="invisible"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
</LinearLayout>
<fragment
android:id="#+id/fragmentProductSteps"
android:name="com.example.alknakralar.kios.Helpers.BlankFragment"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginStart="24dp"
android:layout_marginLeft="24dp"
android:layout_marginTop="16dp"
android:layout_marginEnd="24dp"
android:layout_marginRight="24dp"
android:layout_marginBottom="8dp"
app:layout_constraintBottom_toTopOf="#+id/orderProductLayout"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/gvProductGroups"
app:layout_constraintTop_toBottomOf="#+id/linearLayout" />
<Button
android:id="#+id/btnCancelCurrentOrder2"
android:layout_width="125dp"
android:layout_height="0dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="8dp"
android:background="#ff0000"
android:text="SEPETI BOSALT"
android:textColor="#FFFFFF"
android:textSize="24sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="#+id/imgBackFromProducts"
app:layout_constraintTop_toBottomOf="#+id/fragmentProductSteps" />
<ImageView
android:id="#+id/imgBackFromProducts"
android:layout_width="70dp"
android:layout_height="0dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="#+id/fragmentProductSteps"
app:srcCompat="#drawable/back" />
</android.support.constraint.ConstraintLayout>
How can i fix this issue ?

Sugession: Why are you using grid view and setting adapter to it where you have another approach and commonly used approach.
Which is to use recycler view and set its layout manager as GridLayout manager
Below single line will make your job done
recyclerView.setLayoutManager(new GridLayoutManager(this, numberOfColumns));