Divider Item decoration for RecyclerView in Kotlin with paddings

ListPaddingDecoration.kt

import android.content.Context
import android.graphics.Canvas
import android.graphics.drawable.Drawable
import android.support.v4.content.ContextCompat
import android.support.v7.widget.RecyclerView

class ListPaddingDecoration(
    context: Context,
    val paddingLeft: Int,
    val paddingRight: Int
) : RecyclerView.ItemDecoration() {

    private var mDivider: Drawable? = null

    init {
        mDivider = ContextCompat.getDrawable(context, R.drawable.divider_medium)
    }

    override fun onDrawOver(c: Canvas, parent: RecyclerView, state: RecyclerView.State?) {

        val left = parent.paddingLeft + paddingLeft
        val right = parent.width - parent.paddingRight + paddingRight

        val childCount = parent.childCount
        for (i in 0 until childCount) {
            val child = parent.getChildAt(i)
            val params = child.layoutParams as RecyclerView.LayoutParams
            val top = child.bottom + params.bottomMargin
            val bottom = top + (mDivider?.intrinsicHeight ?: 0)

            mDivider?.let {
                it.setBounds(left, top, right, bottom)
                it.draw(c)
            }

        }
    }
}

You just need to specify a color in R.drawable.divider_medium

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid android:color="@android:color/black" />
    <size
        android:height="1dp"
        android:width="1dp" />

</shape>

and add it to your recyclerView

recyclerView.addItemDecoration(
    ListPaddingDecoration(
        activity as Activity,
        resources.getDimension(80),
        0
    )
)

Optim: set a custom drawable and orientation.

A little mistake it's val right = parent.width - parent.paddingRight - paddingRight

But thank you it helps me !