taskrecreationg.kt

toolbar.setNavigationOnClickListener {
            val upIntent: Intent? = NavUtils.getParentActivityIntent(activity!!)

            when {
                upIntent == null -> throw IllegalStateException("No Parent Activity Intent")
                NavUtils.shouldUpRecreateTask(activity!!, upIntent) -> {
                    TaskStackBuilder.create(activity!!)
                            .addNextIntentWithParentStack(upIntent)
                            .startActivities()
                }
                else -> {
                    NavUtils.navigateUpTo(activity!!, upIntent)
                }
            }
        }