MainActivity.kt
package com.cfsuman.kotlintutorials
import android.graphics.Color
import android.os.Bundle
import android.view.View
import android.widget.*
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
// Get the widgets from XML layout
val textView = findViewById<TextView>(R.id.text_view)
val button = findViewById<Button>(R.id.button);
val button2 = findViewById<Button>(R.id.button2);
val button3 = findViewById<Button>(R.id.button3);
val button4 = findViewById<Button>(R.id.button4);
// Counter to count button click
var counter: Int = 0;
// Set a click listener for button widget
button.setOnClickListener{
counter++
textView.text = "Click counter : $counter"
}
// Another way to set button click listener
button2.setOnClickListener(object: View.OnClickListener {
override fun onClick(v: View?) {
counter++
textView.text = "Click counter : $counter"
v?.setBackgroundColor(
Color.parseColor("#7C0A02")
)
}
})
// Another way to set button click listener
button3.setOnClickListener({ v->
counter++
textView.text = "Click counter : $counter"
v.setBackgroundColor(
Color.parseColor("#2E5894")
)
})
// Another way to set button click listener
button4.setOnClickListener{
counter++;
textView.text = "Click counter : $counter"
it.setBackgroundColor(
Color.parseColor("#4B6F44")
)
}
}
}
activity_main.xml
<?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"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/rootLayout"
android:padding="24dp"
android:background="#F8F8F8">
<TextView
android:id="@+id/text_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:fontFamily="sans-serif"
android:padding="16dp"
android:text="Click Counter"
android:textSize="24sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="24dp"
android:text="First Button"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/text_view" />
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="4dp"
android:text="Second Button"
app:layout_constraintStart_toStartOf="@+id/button"
app:layout_constraintTop_toBottomOf="@+id/button" />
<Button
android:id="@+id/button3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="4dp"
android:text="Third Button"
app:layout_constraintStart_toStartOf="@+id/button2"
app:layout_constraintTop_toBottomOf="@+id/button2" />
<Button
android:id="@+id/button4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="4dp"
android:text="Fourth Button"
app:layout_constraintStart_toStartOf="@+id/button3"
app:layout_constraintTop_toBottomOf="@+id/button3" />
</androidx.constraintlayout.widget.ConstraintLayout>
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