class MainActivity : AppCompatActivity() {
 
  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
 
    textView1.text = formatCurrency(1f, CURRENCY_US_DOLLARS, LANGUAGE_ENGLISH, COUNTRY_US)
    textView2.text = formatCurrency(1f, CURRENCY_US_DOLLARS, LANGUAGE_ENGLISH, COUNTRY_CANADA)
    textView3.text = formatCurrency(1f, CURRENCY_US_DOLLARS, LANGUAGE_ENGLISH, COUNTRY_AUSTRALIA)
  }
 
  private fun formatCurrency(amount: Float, currency: String, language: String, country: String) =
      currencyInLocale(currency, language, country).format(amount)
 
  private fun currencyInLocale(
      currencyCode: String,
      language: String,
      country: String = "",
      variant: String = ""): NumberFormat =
      Locale(language, country, variant).let {
        NumberFormat.getCurrencyInstance(it).apply {
          currency = Currency.getInstance(currencyCode)
        }
      }
 
  companion object {
    private const val CURRENCY_US_DOLLARS: String = "USD"
    private const val LANGUAGE_ENGLISH: String = "EN"
    private const val COUNTRY_US: String = "US"
    private const val COUNTRY_CANADA: String = "CA"
    private const val COUNTRY_AUSTRALIA: String = "AU"
  }
}