Android ProgressBar Using Kotlin

Filed Under: Android

In this tutorial, we’ll be discussing an implementing ProgressBar in our Android Application using Kotlin.

ProgressBar

ProgressBar is a UI element that is used to display the Progress on the screen. A ProgressBar is usually used to define the download/upload progress on the screen.

A ProgressBar can be of two types:

  • Determinate ProgressBar – This is used when you can track and show the progress completed.
  • Indeterminate ProgressBar – This one goes infinitely until stopped

A ProgressDialog would hold a ProgressBar inside an Alert Dialog. ProgressDialog is now deprecated since it isn’t a good idea to show long progress in a dialog while blocking the screen.

Following are the important attributes that can be set on a ProgressBar

  • android:indeterminate : Used to specify the boolean value indicating the type of the ProgressBar
  • android:max – The upper limit of the progress
  • android:min – The lower limit of the progress
  • android:progress – The steps by which the progress would be incremented.
  • android:minWidth and minHeight – Used to define the dimensions of the ProgressBar
  • android:progressBarTint – The tint color of the progress completed of the ProgressBar
  • android:progressBarBackgroundTint – The tint color of the progress completed of the ProgressBar
  • style – Used to set the style of the ProgressBar. By default it is circular. We can set the style as @style/Widget.AppCompat.ProgressBar.Horizontal for the Horizontal ProgressBar
  • android:progressDrawable – Is used to set a drawable for the progress.
  • android:secondaryProgress – Indicates the secondary progress value. This is used when we want to show the sub-downloads/subtasks progress.

By default, the tint colors are set to the colorAccent defined in the styles.xml.

A Basic Circular InDeterminate ProgressBar looks like this:


<ProgressBar
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:minHeight="50dp"
        android:minWidth="50dp" />

In the following section, we’ll be implementing the various types of ProgressBars in our Android Studio Project using Kotlin.

Project Structure

android progressbar project structure

Code

The code for the activity_main.xml layout is given below:


<?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"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical"
    tools:context=".MainActivity">


    <ProgressBar
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:minHeight="50dp"
        android:minWidth="50dp" />


    <ProgressBar
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:indeterminate="true"
        android:minHeight="50dp"
        android:minWidth="200dp" />


    <TextView
        android:id="@+id/textViewHorizontalProgress"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="0" />


    <ProgressBar
        android:id="@+id/progressBarHorizontal"
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:indeterminate="false"
        android:max="100"
        android:minHeight="50dp"
        android:minWidth="200dp"
        android:progress="1"
        android:progressBackgroundTint="@android:color/darker_gray"
        android:progressTint="@color/colorPrimary" />


    <Button
        android:id="@+id/btnProgressBarHorizontal"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="horizontalDeterminate"
        android:text="DETERMINATE HORIZONTAL PROGRESS BAR" />


    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

        <ProgressBar
            android:id="@+id/progressBarSecondary"
            style="@style/Widget.AppCompat.ProgressBar.Horizontal"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:minHeight="150dp"
            android:padding="8dp"
            android:minWidth="150dp"
            android:progressDrawable="@drawable/progress_states" />

        <TextView
            android:id="@+id/textViewPrimary"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:textColor="#000" />

        <TextView
            android:id="@+id/textViewSecondary"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="25dp"
            android:layout_below="@+id/progressBarSecondary"
            android:textColor="@color/colorPrimaryDark" />


    </RelativeLayout>

    <Button
        android:id="@+id/btnProgressBarSecondary"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="DETERMINATE SECONDARY PROGRESS BAR" />


</LinearLayout>

In the last progress bar, we’ve set a progress drawable on the Horizontal ProgressBar.
The drawable.xml file is: progress_states.xml


<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@android:id/background">
        <shape android:shape="oval">
            <stroke
                android:width="4dp"
                android:color="@color/colorPrimary" />
            <solid android:color="@android:color/white" />
        </shape>
    </item>
    <item android:id="@android:id/secondaryProgress">
        <clip
            android:clipOrientation="vertical"
            android:gravity="bottom">
            <shape android:shape="oval">
                <stroke
                    android:width="4dp"
                    android:color="@android:color/black" />
                <solid android:color="@android:color/white" />
            </shape>
        </clip>
    </item>
    <item android:id="@android:id/progress">
        <clip
            android:clipOrientation="vertical"
            android:gravity="bottom">
            <shape android:shape="oval">
                <stroke
                    android:width="4dp"
                    android:color="@color/colorAccent" />
                <solid android:color="#F288F8" />
            </shape>
        </clip>
    </item>
</layer-list>

In this drawable, we’ve created different states of the drawable. All are circular shaped. Each layer would be displayed for the different states : idle, secondary progress, primary progress.

Let’s look at the MainActivity.kt file:


package net.androidly.androidlyprogressbar

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.os.Handler
import android.view.View
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {


    var isStarted = false
    var progressStatus = 0
    var handler: Handler? = null
    var secondaryHandler: Handler? = Handler()
    var primaryProgressStatus = 0
    var secondaryProgressStatus = 0

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


        handler = Handler(Handler.Callback {
            if (isStarted) {
                progressStatus++
            }
            progressBarHorizontal.progress = progressStatus
            textViewHorizontalProgress.text = "${progressStatus}/${progressBarHorizontal.max}"
            handler?.sendEmptyMessageDelayed(0, 100)

            true
        })

        handler?.sendEmptyMessage(0)


        btnProgressBarSecondary.setOnClickListener {
            primaryProgressStatus = 0
            secondaryProgressStatus = 0

            Thread(Runnable {
                while (primaryProgressStatus < 100) {
                    primaryProgressStatus += 1

                    try {
                        Thread.sleep(1000)
                    } catch (e: InterruptedException) {
                        e.printStackTrace()
                    }

                    startSecondaryProgress()
                    secondaryProgressStatus = 0

                    secondaryHandler?.post {
                        progressBarSecondary.progress = primaryProgressStatus
                        textViewPrimary.text = "Complete $primaryProgressStatus% of 100"

                        if (primaryProgressStatus == 100) {
                            textViewPrimary.text = "All tasks completed"
                        }
                    }
                }
            }).start()
        }

    }

    fun startSecondaryProgress() {
        Thread(Runnable {
            while (secondaryProgressStatus < 100) {
                secondaryProgressStatus += 1

                try {
                    Thread.sleep(10)
                } catch (e: InterruptedException) {
                    e.printStackTrace()
                }

                secondaryHandler?.post {
                    progressBarSecondary.setSecondaryProgress(secondaryProgressStatus)
                    textViewSecondary.setText("Current task progress\n$secondaryProgressStatus% of 100")

                    if (secondaryProgressStatus == 100) {
                        textViewSecondary.setText("Single task complete.")
                    }
                }
            }
        }).start()
    }

    fun horizontalDeterminate(view: View) {
        isStarted = !isStarted
    }

}

horizontalDeterminate Kotlin function is triggered when the first Button gets clicked. It is used to start/stop Horizontal ProgressBar.
A Handler is associated with a single thread. It is used to send messages to the Thread.

btnProgressBarSecondary click triggers the second progress bar. In this, we have created two handlers. One for the normal progress and second for the subtasks. In each of them, we set the thread to sleep.

For the secondary thread, the sleep time is 1/100 of the primary progress thread.
The progress value is displayed on the TextView.

The output of the above application in action is given below:

android progress bar output

This brings an end to this tutorial. You can download the project from the link below:

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