Issue
package com.example.colormyviews
import android.graphics.Color
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.Button
import android.widget.TextView
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
setListeners()
}
private fun setListeners(){
val boxOneText = findViewById<TextView>(R.id.box_one_text)
val boxTwoText = findViewById<TextView>(R.id.box_two_text)
val boxThreeText = findViewById<TextView>(R.id.box_three_text)
val boxFourText = findViewById<TextView>(R.id.box_four_text)
val boxFiveText = findViewById<TextView>(R.id.box_five_text)
val rootConstraintLayout = findViewById<View>(R.id.info_text)
val redButton = findViewById<Button>(R.id.red_button)
val greenButton = findViewById<Button>(R.id.green_button)
val yellowButton = findViewById<Button>(R.id.yellow_button)
val clickableViews: List<View> =
listOf(
boxOneText, boxTwoText, boxThreeText,
boxFourText, boxFiveText, rootConstraintLayout,
redButton, greenButton, yellowButton
)
for (item in clickableViews){
item.setOnClickListener{makeColored(it)}
}
}
private fun makeColored(view: View){
when (view.id) {
// Boxes using Color class colors for the background
R.id.box_one_text -> view.setBackgroundColor(Color.DKGRAY)
R.id.box_two_text -> view.setBackgroundColor(Color.GRAY)
R.id.box_three_text -> view.setBackgroundColor(Color.BLUE)
R.id.box_four_text -> view.setBackgroundColor(Color.MAGENTA)
R.id.box_five_text -> view.setBackgroundColor(Color.BLUE)
R.id.red_button -> box_three_text.setBackgroundResource(R.color.my_red)
R.id.yellow_button -> box_four_text.setBackgroundResource(R.color.my_yellow)
R.id.green_button -> box_five_text.setBackgroundResource(R.color.my_green)
else -> view.setBackgroundColor(Color.LTGRAY)
}
}
}
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:id="@+id/constraint_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="@+id/box_one_text"
style="@style/whiteBox"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginLeft="16dp"
android:layout_marginTop="@dimen/margin_wide"
android:layout_marginRight="16dp"
android:text="@string/box_one"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/box_two_text"
style="@style/whiteBox"
android:layout_width="130dp"
android:layout_height="130dp"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
android:text="@string/box_two"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/box_one_text" />
<TextView
android:id="@+id/box_three_text"
style="@style/whiteBox"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="@dimen/margin_wide"
android:layout_marginEnd="@dimen/margin_wide"
android:text="@string/box_three"
app:layout_constraintBottom_toTopOf="@+id/box_four_text"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@+id/box_two_text"
app:layout_constraintTop_toTopOf="@+id/box_two_text" />
<TextView
android:id="@+id/box_four_text"
style="@style/whiteBox"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="@dimen/margin_wide"
android:layout_marginTop="@dimen/margin_wide"
android:layout_marginEnd="@dimen/margin_wide"
android:layout_marginBottom="@dimen/margin_wide"
android:text="@string/box_four"
app:layout_constraintBottom_toTopOf="@+id/box_five_text"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@+id/box_two_text"
app:layout_constraintTop_toBottomOf="@+id/box_three_text" />
<TextView
android:id="@+id/box_five_text"
style="@style/whiteBox"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="@dimen/margin_wide"
android:layout_marginEnd="@dimen/margin_wide"
android:text="@string/box_five"
app:layout_constraintBottom_toBottomOf="@+id/box_two_text"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@+id/box_two_text"
app:layout_constraintTop_toBottomOf="@+id/box_four_text" />
<TextView
android:id="@+id/label_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:fontFamily="@font/roboto"
android:text="@string/how_to_play"
android:textSize="24sp"
android:textStyle="bold"
app:layout_constraintBaseline_toBaselineOf="@+id/info_text"
app:layout_constraintStart_toStartOf="parent" />
<TextView
android:id="@+id/info_text"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
android:fontFamily="@font/roboto"
android:text="@string/tap_the_boxes_and_buttons"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toEndOf="@+id/label_text"
app:layout_constraintTop_toBottomOf="@+id/box_two_text"
app:layout_constraintVertical_bias="0.0" />
<Button
android:id="@+id/red_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:text="@string/button_red"
app:layout_constraintBaseline_toBaselineOf="@+id/yellow_button"
app:layout_constraintEnd_toStartOf="@+id/yellow_button"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent" />
<Button
android:id="@+id/yellow_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginEnd="16dp"
android:layout_marginBottom="16dp"
android:text="@string/button_yellow"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="@+id/green_button"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toEndOf="@+id/red_button"
app:layout_constraintTop_toBottomOf="@+id/info_text"
app:layout_constraintVertical_bias="1.0"/>
<Button
android:id="@+id/green_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="16dp"
android:text="@string/button_green"
app:layout_constraintBaseline_toBaselineOf="@+id/yellow_button"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toEndOf="@+id/yellow_button" />
</androidx.constraintlayout.widget.ConstraintLayout>
In makeColored() function, while calling setBackgroundResource() on box_three_text, box_four_text, box_five_text. It throws me an ' Unresolved reference error '. However id's with same name has been declared in XML file. I can't understand where the problem lies, Please help me to understand what's going on and why it is unable to read id's in Mainactivity.kt which has been declared in Mainactivity.xm.
Solution
instead of id use reference
R.id.red_button -> boxThreeText.setBackgroundResource(R.color.my_red)
R.id.yellow_button -> boxFourText.setBackgroundResource(R.color.my_yellow)
R.id.green_button -> boxFiveText.setBackgroundResource(R.color.my_green)
and make these buttons global variable. You can directly use ids if you are using kotlin synthetic, however I can't see any such import in your code. (And anyway you should not be using be kotlin synthetic as Kotlin-extension plugin is deprecated)
Answered By - Kunu
Answer Checked By - Candace Johnson (JavaFixing Volunteer)
