DialogFragmentBase.kt

class CustomDialogFragment : DialogFragment() {
    interface OnDialogActionListerner {

        fun onPositiveButtonClicked()

        fun onNegativeButtonClicked()
    }

    class Builder {

        // ActivityかFragmentどちらかは必ずInputさせる
        internal val mActivity: AppCompatActivity?

        internal val mFragment: Fragment?

        private var mTitle: String? = null

        private var mMessage: String? = null

        private var mPositiveButtonLabel: String? = null

        private var mNeagtiveButtonLabel: String? = null

        constructor(activity: AppCompatActivity) {
            mActivity = activity
            mFragment = null
        }

        constructor(fragment: Fragment) {
            mActivity = null
            mFragment = fragment
        }

        fun setTitle(title: String): Builder {
            mTitle = title
            return this
        }

        // 他のケース作ってないけど、同じ形式でResからの入力サポートできる
        fun setTitle(resId: Int): Builder {
            return setTitle(context.resources.getString(resId))
        }

        fun setMessage(message: String): Builder {
            mMessage = message
            return this
        }

        fun setPositiveButtonLabel(positiveButtonLabel: String): Builder {
            mPositiveButtonLabel = positiveButtonLabel
            return this
        }

        fun setNeagtiveButtonLabel(neagtiveButtonLabel: String): Builder {
            mNeagtiveButtonLabel = neagtiveButtonLabel
            return this
        }

        fun build(): CustomDialogFragment? {

            val bundle = Bundle()
            bundle.putString(BUNDLE_KEY_TITLE, mTitle)
            bundle.putString(BUNDLE_KEY_MESSAGE, mMessage)
            bundle.putString(BUNDLE_KEY_POSITIVE_LABEL, mPositiveButtonLabel)
            bundle.putString(BUNDLE_KEY_NEGATIVE_LABEL, mNeagtiveButtonLabel)

            val fragment = CustomDialogFragment()
            fragment.arguments = bundle

            return fragment
        }

        private val context: Context
            get() = (mActivity ?: mFragment!!.activity).applicationContext

        companion object {

            val BUNDLE_KEY_TITLE = "title"
            val BUNDLE_KEY_MESSAGE = "message"
            val BUNDLE_KEY_POSITIVE_LABEL = "positive_label"
            val BUNDLE_KEY_NEGATIVE_LABEL = "negative_label"
        }
    }

    var mListener: OnDialogActionListerner? = null

    private var shown: Boolean = false

    override fun onAttach(context: Context?) {
        super.onAttach(context)
    }

    override fun onDetach() {
        mListener = null
        super.onDetach()
    }


    override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
        val bundle = arguments

        // DialogのLayoutを変更したいのであれば、ここでinflateする
        var view = activity.layoutInflater.inflate(R.layout.dialog, null, false)


        val builder = AlertDialog.Builder(activity)

        if (bundle.getString(Builder.BUNDLE_KEY_TITLE) != null) {
            builder.setTitle(bundle.getString(Builder.BUNDLE_KEY_TITLE))
        }

        if (bundle.getString(Builder.BUNDLE_KEY_MESSAGE) != null) {
            builder.setMessage(bundle.getString(Builder.BUNDLE_KEY_MESSAGE))
        }
        if (bundle.getString(Builder.BUNDLE_KEY_POSITIVE_LABEL) != null) {
            builder.setPositiveButton(bundle.getString(Builder.BUNDLE_KEY_POSITIVE_LABEL),
                    object : DialogInterface.OnClickListener {
                        override fun onClick(dialog: DialogInterface?, which: Int) {
                            mListener?.onPositiveButtonClicked()
                        }
                    })
        }

        if (bundle.getString(Builder.BUNDLE_KEY_NEGATIVE_LABEL) != null) {
            builder.setNegativeButton(bundle.getString(Builder.BUNDLE_KEY_NEGATIVE_LABEL),
                    object : DialogInterface.OnClickListener {
                        override fun onClick(dialog: DialogInterface?, which: Int) {
                            mListener?.onNegativeButtonClicked()
                        }
                    })
        }

        builder.setView(view)

        return builder.create()
    }

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)

    }

    override fun onResume() {
        super.onResume()

        // Dialogの大きさを変更するときはここで行う
        var lp = dialog.window.attributes
        lp.width = (resources.displayMetrics.widthPixels * 0.8).toInt()
        lp.height = ViewGroup.LayoutParams.WRAP_CONTENT

        dialog.window.attributes = lp
    }

    override fun show(manager: FragmentManager?, tag: String?) {
        // show, onDissmissをoverrideしてDialogが重なった表示とならないようにしている
        if (shown) return

        super.show(manager, tag)
        shown = true
    }

    override fun onDismiss(dialog: DialogInterface?) {
        shown = false
        super.onDismiss(dialog)
    }
}

コンバートしたソースがベースだから、まだ粗いっぽい。