Android Get Country Emoji Flag Using Locale

When I first wrote this answer I somehow overlooked that I've only worked on Android via React Native!

Anyway, here's my JavaScript solution that works with or without ES6 support.

    function countryCodeToFlagEmoji(country) {
      return typeof String.fromCodePoint === "function"
        ? String.fromCodePoint(...[...country].map(c => c.charCodeAt() + 0x1f185))
        : [...country]
            .map(c => "\ud83c" + String.fromCharCode(0xdd85 + c.charCodeAt()))
            .join("");
    }

console.log(countryCodeToFlagEmoji("au"));
console.log(countryCodeToFlagEmoji("aubdusca"));

If you want to pass in the country codes as capital letters instead, just change the two offsets to 0x1f1a5 and 0xdda5.

Emoji is a Unicode symbols. Based on the Unicode character table Emoji flags consist of 26 alphabetic Unicode characters (A-Z) intended to be used to encode ISO 3166-1 alpha-2 two-letter country codes (wiki).

That means it is possible to split two-letter country code and convert each A-Z letter to regional indicator symbol letter:

private String localeToEmoji(Locale locale) {
    String countryCode = locale.getCountry();
    int firstLetter = Character.codePointAt(countryCode, 0) - 0x41 + 0x1F1E6;
    int secondLetter = Character.codePointAt(countryCode, 1) - 0x41 + 0x1F1E6;
    return new String(Character.toChars(firstLetter)) + new String(Character.toChars(secondLetter));
}

Or in Kotlin, for example (assuming UTF-8):

val Locale.flagEmoji: String
    get() {
      val firstLetter = Character.codePointAt(country, 0) - 0x41 + 0x1F1E6
      val secondLetter = Character.codePointAt(country, 1) - 0x41 + 0x1F1E6
      return String(Character.toChars(firstLetter)) + String(Character.toChars(secondLetter))
    }

Where 0x41 represents uppercase A letter and 0x1F1E6 is REGIONAL INDICATOR SYMBOL LETTER A in the Unicode table.

Note: This code example is simplified and doesn't have required checks related to country code, that could be not available inside the locale.

Based on this answer, I wrote a Kotlin version below using extension function.

I also added some checks to handle unknown country code.

/**
 * This method is to change the country code like "us" into 🇺🇸
 * Stolen from https://stackoverflow.com/a/35849652/75579
 * 1. It first checks if the string consists of only 2 characters: ISO 3166-1 alpha-2 two-letter country codes (https://en.wikipedia.org/wiki/Regional_Indicator_Symbol).
 * 2. It then checks if both characters are alphabet
 * do nothing if it doesn't fulfil the 2 checks
 * caveat: if you enter an invalid 2 letter country code, say "XX", it will pass the 2 checks, and it will return unknown result
 */
fun String.toFlagEmoji(): String {
    // 1. It first checks if the string consists of only 2 characters: ISO 3166-1 alpha-2 two-letter country codes (https://en.wikipedia.org/wiki/Regional_Indicator_Symbol).
    if (this.length != 2) {
        return this
    }

    val countryCodeCaps = this.toUpperCase() // upper case is important because we are calculating offset
    val firstLetter = Character.codePointAt(countryCodeCaps, 0) - 0x41 + 0x1F1E6
    val secondLetter = Character.codePointAt(countryCodeCaps, 1) - 0x41 + 0x1F1E6

    // 2. It then checks if both characters are alphabet
    if (!countryCodeCaps[0].isLetter() || !countryCodeCaps[1].isLetter()) {
        return this
    }

    return String(Character.toChars(firstLetter)) + String(Character.toChars(secondLetter))
}

Runnable Code Snippet

I also included a runnable Kotlin snippet using Kotlin Playground. In order to run the snippet you need to:

1. click "Show code snippet"
2. click "Run Code Snippet"
3. click the play button at the right top of the generated console
4. scroll to the bottom to see the result (it's hidden..)

   <script src="https://unpkg.com/[email protected]/dist/playground.min.js" data-selector=".code"></script>
   
   
   <div class="code" style="display:none;">
   
   /**
    * This method is to change the country code like "us" into 🇺🇸
    * Stolen from https://stackoverflow.com/a/35849652/75579
    * 1. It first checks if the string consists of only 2 characters: ISO 3166-1 alpha-2 two-letter country codes (https://en.wikipedia.org/wiki/Regional_Indicator_Symbol).
    * 2. It then checks if both characters are alphabet
    * do nothing if it doesn't fulfil the 2 checks
    * caveat: if you enter an invalid 2 letter country code, say "XX", it will pass the 2 checks, and it will return unknown result
    */
   fun String.toFlagEmoji(): String {
       // 1. It first checks if the string consists of only 2 characters: ISO 3166-1 alpha-2 two-letter country codes (https://en.wikipedia.org/wiki/Regional_Indicator_Symbol).
       if (this.length != 2) {
           return this
       }
   
       val countryCodeCaps = this.toUpperCase() // upper case is important because we are calculating offset
       val firstLetter = Character.codePointAt(countryCodeCaps, 0) - 0x41 + 0x1F1E6
       val secondLetter = Character.codePointAt(countryCodeCaps, 1) - 0x41 + 0x1F1E6
   
       // 2. It then checks if both characters are alphabet
       if (!countryCodeCaps[0].isLetter() || !countryCodeCaps[1].isLetter()) {
           return this
       }
   
       return String(Character.toChars(firstLetter)) + String(Character.toChars(secondLetter))
   }
   
   fun main(args: Array&lt;String&gt;){
     println("us".toFlagEmoji())
     println("AF".toFlagEmoji())
     println("BR".toFlagEmoji())
     println("MY".toFlagEmoji())
     println("JP".toFlagEmoji())
   }
   
   </div>