android kotlin - ProgressBar example

MainActivity.kt

package com.cfsuman.kotlintutorials

import android.app.Activity
import android.os.Bundle
import android.os.Handler
import android.os.Looper
import android.widget.Button
import android.widget.ProgressBar
import android.widget.TextView


class MainActivity : Activity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)


        // Get the widgets reference from XML layout
        val button = findViewById<Button>(R.id.button)
        val textView = findViewById<TextView>(R.id.textView)
        val progressBar = findViewById<ProgressBar>(R.id.progressBar)


        // Variable to hold progress status
        var progressStatus = 0;

        // Initialize a new Handler instance
        val handler: Handler = Handler(Looper.getMainLooper())


        // Set a click listener for button widget
        button.setOnClickListener{
            // Disable the button itself
            it.isEnabled = false

            // Start the lengthy operation in a background thread
            Thread {
                while (progressStatus < 100) {
                    // Update the progress status
                    progressStatus += 1

                    // Try to sleep the thread for 50 milliseconds
                    try {
                        Thread.sleep(50)
                    } catch (e: InterruptedException) {
                        e.printStackTrace()
                    }

                    // Update the progress bar
                    handler.post(Runnable {
                        progressBar.progress = progressStatus

                        // Show the progress on text view
                        textView.text = progressStatus.toString()
                    })
                }
            }.start() // Start the operation
        }
    }
}

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/rootLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="24dp"
    android:background="#DCDCDC">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="36dp"
        android:fontFamily="sans-serif"
        android:textSize="24sp"
        android:textStyle="bold"
        tools:text="TextView"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <ProgressBar
        android:id="@+id/progressBar"
        style="@style/Widget.AppCompat.ProgressBar.Horizontal"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:text="Start Task"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/progressBar" />

</androidx.constraintlayout.widget.ConstraintLayout>