Mastering Kotlin

Creating factory methods for activities and fragments

A common pattern for the creation of new activities or fragments is to create static factory methods to start an activity, or to create an intent, or to create a new instance of Fragment. When using Kotlin, we can accomplish this using a companion object, which is shown in the following code block with the definition of Factory:

companion object Factory {    const val EXTRA_ID = "extra_id"    @JvmStatic    fun createIntent(context: Context, id: String) = Intent(context, DetailsActivity::class.java).apply { putExtra(EXTRA_ID, id) }}

Additionally, you could use a top-level function or extension function to achieve similar behavior, as follows:

fun createDetailsIntent(context: Context, id: String) ...