How I create Intents and start Activities in Kotlin

0_UserActivity.kt

fun Context.UserDetailIntent(user: User): Intent {
    return Intent(this, UserDetailActivity::class.java).apply {
        putExtra(INTENT_USER_ID, user.id)
    }
}

private const val INTENT_USER_ID = "user_id"

class UserDetailActivity : Activity() {

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

        val userId = intent.getStringExtra(INTENT_USER_ID)
        requireNotNull(userId) { "no user_id provided in Intent extras" }
    }
}

1_Usage.kt

// Usage in other Activities
class OtherActivity: Activity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        //...
        userList.clickListener { user ->
            val options = buildYourOwnOptionsDependingOnYourNeed() // only when required
            startActivity(UserDetailIntent(user), options)
        }
    }
}