Detecting if a character in a String is an emoticon (using Android)

Question

Like the title says. I want to find out if a given java String contains an emoticon.

I can't use Character.UnicodeBlock.of(char) == Character.UnicodeBlock.EMOTICONS since that requires API level 19.

I found this code for iOS but it isn't really applicable since it looks like java and objective-c handle surrogate pairs in different manners.

The documentations I've looked through tell me that:

A char value, therefore, represents Basic Multilingual Plane (BMP) code points, including the surrogate code points, or code units of the UTF-16 encoding

I'm not quite sure what that means. Does that simply mean that they also include the BMP point as their first number?

According to Wikipedia the emoticon set lies between 0x1f600 and 0x1f64f but I don't know how to check if the char is in that range.

I had hoped that something like this would work but it didn't

if (0x1f600 <= a && a <= 0x1f64f)
{
    Print.d("Unicode", "groovy!");
}

So how do I go about this?

Answer 1

Four years later...

At this time, it might make more sense to take advantage of EmojiCompat. This code presumes you initialized EmojiCompat when your app was starting up. The basic idea here is to have EmojiCompat process your CharSequence, inserting instances of EmojiSpan wherever any emoji appear, and then examine the results.

public static boolean containsEmoji(CharSequence charSequence) {
    boolean result = false;
    CharSequence processed = EmojiCompat.get().process(charSequence, 0, charSequence.length() -1, Integer.MAX_VALUE, EmojiCompat.REPLACE_STRATEGY_ALL);
    if (processed instanceof Spannable) {
        Spannable spannable = (Spannable) processed;
        result = spannable.getSpans(0, spannable.length() - 1, EmojiSpan.class).length > 0;
    }
    return  result;
}

If you want to collect a list of the unique emoji that appear within a given CharSequence, you could do something like this, iterating over the results of getSpans() and finding the start and end of each span to capture the emoji discovered by EmojiCompat:

@NonNull
public static List<String> getUniqueEmoji(CharSequence charSequence) {
    Set<String> emojiList = new HashSet<>();
    CharSequence processed = EmojiCompat.get().process(charSequence, 0, charSequence.length() -1, Integer.MAX_VALUE, EmojiCompat.REPLACE_STRATEGY_ALL);
    if (processed instanceof Spannable) {
        Spannable spannable = (Spannable) processed;

        EmojiSpan[] emojiSpans = spannable.getSpans(0, spannable.length() - 1, EmojiSpan.class);
        for (EmojiSpan emojiSpan : emojiSpans) {
            int spanStart = spannable.getSpanStart(emojiSpan);
            int spanEnd = spannable.getSpanEnd(emojiSpan);
            CharSequence emojiCharSequence = spannable.subSequence(spanStart, spanEnd);
            emojiList.add(String.valueOf(emojiCharSequence));
        }
    }
    return emojiList.size() > 0 ? new ArrayList<>(emojiList) : new ArrayList<String>();
}

UPDATE: Here's an example of EmojiCompat initialization. This static method can be called from your Application onCreate() method, passing in the Application itself as the Context param.

@JvmStatic
fun initEmojiCompat(context: Context) {
    if (emojiCompatConfig != null) {
        // alternatively, EmojiCompat.reset() could be called here
        logger().w(LOGTAG, "EmojiCompat already initialized.")
        return
    }

    // "Noto Color Emoji Compat" doesn't have graphics for the following emojis:
    // U+1F5E3 "speaking head" (required)
    // U+1F441 "eye" (required)
    // U+1F575 "detective" (nice to have)
    val fontRequest = FontRequest(
        "com.google.android.gms.fonts",
        "com.google.android.gms",
        "Noto Color Emoji Compat",
        R.array.com_google_android_gms_fonts_certs
    )

    emojiCompatConfig = FontRequestEmojiCompatConfig(context, fontRequest)
        .setReplaceAll(false)
        .setEmojiSpanIndicatorEnabled(false)
        .registerInitCallback(initCallback)
        .also {
            EmojiCompat.init(it)
        }
}

Answer 2

I was in fact able to use the linked iOS code to create the following function. I didn't realize that a String that contains, for example, a single emoticon will have a length of 2. So you can check if a character is in fact a surrogate.

I'm not entirely sure how to handle else if (substring.length > 1) from the iOS code but I think Character.isHighSurrogate(myChar) does the same job in that instance.

private boolean containsIllegalCharacters(String displayName)
{
    final int nameLength = displayName.length();

    for (int i = 0; i < nameLength; i++)
    {
        final char hs = displayName.charAt(i);

        if (0xd800 <= hs && hs <= 0xdbff)
        {
            final char ls = displayName.charAt(i + 1);
            final int uc = ((hs - 0xd800) * 0x400) + (ls - 0xdc00) + 0x10000;

            if (0x1d000 <= uc && uc <= 0x1f77f)
            {
                return true;
            }
        }
        else if (Character.isHighSurrogate(hs))
        {
            final char ls = displayName.charAt(i + 1);

            if (ls == 0x20e3)
            {
                return true;
            }
        }
        else
        {
            // non surrogate
            if (0x2100 <= hs && hs <= 0x27ff)
            {
                return true;
            }
            else if (0x2B05 <= hs && hs <= 0x2b07)
            {
                return true;
            }
            else if (0x2934 <= hs && hs <= 0x2935)
            {
                return true;
            }
            else if (0x3297 <= hs && hs <= 0x3299)
            {
                return true;
            }
            else if (hs == 0xa9 || hs == 0xae || hs == 0x303d || hs == 0x3030 || hs == 0x2b55 || hs == 0x2b1c || hs == 0x2b1b || hs == 0x2b50)
            {
                return true;
            }
        }
    }

    return false;
}