MainActivity.kt
package com.example.jetpack
import android.graphics.Color
import android.os.Bundle
import android.os.Handler
import android.os.Looper
import androidx.appcompat.app.AppCompatActivity
import kotlinx.android.synthetic.main.activity_main.*
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
// start a 5 seconds delayed task using handler
Handler(Looper.getMainLooper()).postDelayed({
textView.text = "Text changed after 5 seconds delay."
},5000)
// initialize an instance of handler
val handler = Handler(Looper.getMainLooper())
// delayed task on button click
button.setOnClickListener {
val runnable = Runnable { // do some task on delay
// set the text view text color to red
textView.setTextColor(Color.RED)
}
// schedule a 4 seconds delayed task
handler.postDelayed(runnable, 4000)
}
}
}
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"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/constraintLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#E5E4E2"
tools:context=".MainActivity">
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:text="Do Task After Delay"
android:backgroundTint="#5946B2"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/textView"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginEnd="16dp"
android:fontFamily="sans-serif-condensed"
android:gravity="center"
android:text="TextView"
android:textColor="#191970"
android:textSize="33sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
tools:text="TextView" />
</androidx.constraintlayout.widget.ConstraintLayout>


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