ModalBottomSheetDialog.kt

package com.lemonboy.modalbottomsheet.dialog

import android.app.Dialog
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import com.google.android.material.bottomsheet.BottomSheetBehavior
import com.google.android.material.bottomsheet.BottomSheetDialog
import com.google.android.material.bottomsheet.BottomSheetDialogFragment
import com.lemonboy.modalbottomsheet.databinding.ItemBottomsheetBinding

class ModalBottomSheetDialog : BottomSheetDialogFragment() {
    private lateinit var binding : ItemBottomsheetBinding

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
        binding = ItemBottomsheetBinding.inflate(inflater, container, false)

        return binding.root
    }

    override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
        // used to show the bottom sheet dialog
        dialog?.setOnShowListener { it ->
            val d = it as BottomSheetDialog
            val bottomSheet = d.findViewById<View>(com.google.android.material.R.id.design_bottom_sheet)
            bottomSheet?.let {
                val behavior = BottomSheetBehavior.from(it)
                behavior.state = BottomSheetBehavior.STATE_EXPANDED
            }
        }
        return super.onCreateDialog(savedInstanceState)
    }

    companion object {
        const val TAG = "ModalBottomSheetDialog"
    }
}