Kotlin - Range seekbar library

i'm using syedowaisali's Range Seekbar, and i'm having trouble getting my TextView to change according to the thumb's position on the bar.

I have the following in my Activity's onCreate:

    val rangeSeekbar = CrystalRangeSeekbar(this)
    rangeSeekbar.setOnRangeSeekbarChangeListener { minValue, maxValue ->
        tv_rent_time_range.text = maxValue.toString()
    }

tv_rent_time_range loads with the maxValue but it doesn't change when i move the right thumb

In his documentation (in Java) it's suppose to look like this:

rangeSeekbar.setOnRangeSeekbarChangeListener(new OnRangeSeekbarChangeListener() {
    @Override
    public void valueChanged(Number minValue, Number maxValue) {
        tvMin.setText(String.valueOf(minValue));
        tvMax.setText(String.valueOf(maxValue));
    }
});

I have a feeling i'm setting up the setOnRangeSeekbarChangeListener wrong in Kotlin

You are creating new object (val rangeSeekbar = CrystalRangeSeekbar(this)) instead of using view from your inflated layout. You can just use:

rangeSeekbar.setOnRangeSeekbarChangeListener { minValue, maxValue ->
    // Do something there  
}

For SeekBar from Android SDK you can receive updates from setOnSeekBarChangeListener.

For CrystalRangeSeekbar from Android SDK you can receive updates from setOnRangeSeekbarChangeListener.

import android.os.Bundle
import android.support.v7.app.AppCompatActivity
import android.widget.SeekBar
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

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

        setupUi()
    }

    private fun setupUi() {
        // Regular SeekBar (from Android SDK)
        seek_bar.setOnSeekBarChangeListener(object : SeekBar.OnSeekBarChangeListener {
            override fun onProgressChanged(seekBar: SeekBar?, progress: Int, fromUser: Boolean) {
                // Update text here
            }

            override fun onStartTrackingTouch(seekBar: SeekBar?) {
            }

            override fun onStopTrackingTouch(seekBar: SeekBar?) {
            }
        })

        crystal_range_seek_bar.setOnRangeSeekbarChangeListener { minValue, maxValue ->
            // Update text here
        }
    }
}