Kotlin - convert UTC to local time

I'm trying to convert a UTC string date to local time, so it's in a more readable format.
I have a `textView` that in my activity layout:

<TextView
android:id="@+id/dateTv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/titleTv"
tools:text="Published Date" />

In my activity:

class FullArticleActivity : AppCompatActivity() {

override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_full_article)

val articleJson = intent.getStringExtra(ARTICLE_KEY)


if(!articleJson.isNullOrBlank()) {
val article = Gson().fromJson<Article>(articleJson, Article::class.java)

val formatter = SimpleDateFormat("yyyy-MM-dd HH:mm:ssZ", Locale.getDefault())
formatter.timeZone = TimeZone.getTimeZone("UTC")
val formattedDate = formatter.parse(article.publishedAt)

titleTv.text = article.title
//UTC string
dateTv.text = article.publishedAt
contentTv.text = article.content

The `publishedAt` string is in this format from the api call `"2018-12-10T19:48:39Z"`. How can I convert this ZULU time format to local time?

Try using Extension Functions

fun String.toDate(dateFormat: String = "yyyy-MM-dd HH:mm:ss", timeZone: TimeZone = TimeZone.getTimeZone("UTC")): Date {
val parser = SimpleDateFormat(dateFormat, Locale.getDefault())
parser.timeZone = timeZone
return parser.parse(this)
}

fun Date.formatTo(dateFormat: String, timeZone: TimeZone = TimeZone.getDefault()): String {
val formatter = SimpleDateFormat(dateFormat, Locale.getDefault())
formatter.timeZone = timeZone
return formatter.format(this)
}

Usage:

"2018-09-10 22:01:00".toDate().formatTo("dd MMM yyyy")

Output: "11 Sep 2018"