Kotlin Android SeekBar

Android SeekBar is a kind of ProgressBar with a draggable thumb. The end user can drag the thumb left and right to move the progress of the song, file download etc.
The SeekBar.OnSeekBarChangeListener interface provides methods to perform even handling for seek bar.
We can create two types of SeekBar in Android

• SeekBar with smooth progress.
• SeekBar with discrete progress point.

The discrete progress point of SeekBar is created using attribute style="@style/Widget.AppCompat.SeekBar.Discrete" and specify the maximum point using attribute max.

Kotlin Android SeekBar Example

In this example, we will create the SeekBar with smooth progress and SeekBar with discrete progress point.

activity_main.xml

Add the SeekBar in the activity_main.xml layout.

< ?xml version="1.0" encoding="utf-8"?>  
< android.support.constraint.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:layout_width="match_parent"  
    android:layout_height="match_parent"  
    tools:context="example.javatpoint.com.kotlinseekbar.MainActivity">  
  
  
    < SeekBar  
        android:id="@+id/seekbar_Default"  
        android:layout_width="match_parent"  
        android:layout_height="wrap_content"  
        android:layout_marginBottom="8dp"  
        android:layout_marginEnd="8dp"  
        android:layout_marginStart="8dp"  
        android:layout_marginTop="8dp"  
        app:layout_constraintBottom_toBottomOf="parent"  
        app:layout_constraintEnd_toEndOf="parent"  
        app:layout_constraintHorizontal_bias="0.0"  
        app:layout_constraintStart_toStartOf="parent"  
        app:layout_constraintTop_toTopOf="parent"  
        app:layout_constraintVertical_bias="0.174" />  
  
    < SeekBar  
        android:id="@+id/seekbar_Discrete"  
        style="@style/Widget.AppCompat.SeekBar.Discrete"  
        android:layout_width="match_parent"  
        android:layout_height="wrap_content"  
        android:layout_marginBottom="8dp"  
        android:layout_marginEnd="8dp"  
        android:layout_marginStart="8dp"  
        android:layout_marginTop="8dp"  
        android:max="10"  
        android:progress="0"  
        app:layout_constraintBottom_toBottomOf="parent"  
        app:layout_constraintEnd_toEndOf="parent"  
        app:layout_constraintHorizontal_bias="1.0"  
        app:layout_constraintStart_toStartOf="parent"  
        app:layout_constraintTop_toTopOf="parent"  
        app:layout_constraintVertical_bias="0.333" />  
< /android.support.constraint.ConstraintLayout>

MainActivity.kt

In this class, we call the SeekBar.OnSeekBarChangeListener interface and override its methods.

package example.javatpoint.com.kotlinseekbar  
  
import android.support.v7.app.AppCompatActivity  
import android.os.Bundle  
import android.widget.SeekBar  
import android.widget.Toast  
  
class MainActivity : AppCompatActivity() {  
    var seekBarNormal: SeekBar? = null  
    var seekBarDiscrete: SeekBar? = null  
    override fun onCreate(savedInstanceState: Bundle?) {  
        super.onCreate(savedInstanceState)  
        setContentView(R.layout.activity_main)  
        seekBarNormal= findViewById(R.id.seekbar_Default)  
        seekBarDiscrete = findViewById(R.id.seekbar_Discrete)  
  
        seekBarNormal?.setOnSeekBarChangeListener(object : SeekBar.OnSeekBarChangeListener {  
            override fun onProgressChanged(seekBar: SeekBar, progress: Int,  
                                           fromUser: Boolean) {  
                Toast.makeText(applicationContext, "seekbar progress: $progress", Toast.LENGTH_SHORT).show()  
            }  
  
            override fun onStartTrackingTouch(seekBar: SeekBar) {  
                Toast.makeText(applicationContext, "seekbar touch started!", Toast.LENGTH_SHORT).show()  
            }  
  
            override fun onStopTrackingTouch(seekBar: SeekBar) {  
                Toast.makeText(applicationContext, "seekbar touch stopped!", Toast.LENGTH_SHORT).show()  
            }  
        })  
  
        seekBarDiscrete?.setOnSeekBarChangeListener(object :SeekBar.OnSeekBarChangeListener{  
            override fun onProgressChanged(seekBar: SeekBar?, progress: Int, fromUser: Boolean) {  
               // TODO("not implemented") //To change body of created functions use File | Settings | File Templates.  
                Toast.makeText(applicationContext, "discrete seekbar progress: $progress", Toast.LENGTH_SHORT).show()  
            }  
  
            override fun onStartTrackingTouch(seekBar: SeekBar?) {  
              //  TODO("not implemented") //To change body of created functions use File | Settings | File Templates.  
                Toast.makeText(applicationContext, "discrete seekbar touch started!", Toast.LENGTH_SHORT).show()  
            }  
  
            override fun onStopTrackingTouch(seekBar: SeekBar?) {  
              //  TODO("not implemented") //To change body of created functions use File | Settings | File Templates.  
                Toast.makeText(applicationContext, "discrete seekbar touch stopped", Toast.LENGTH_SHORT).show()  
            }  
        })  
    }  
}