如何从字符串中删除所有没有可打印的字符+表情符号？

Question

I want to remove all non printable characters + all Emoji from my String.

I tried with that but it doesn't work properly for Emoji:

public static String removeAllNoAsciiChars(String str) {
        if (!TextUtils.isEmpty(str)) {
            str = str.replaceAll("\\p{C}", "");
        }
        return str;
    }

Examples:

"L'alphabet est génial 😀!"

Final result expected: "L'alphabet est génial !"

"Ça c'est du cœur ❤️ :) !"

Final result expected: "Ça c'est du cœur :) !"

Answer 1

The \\\\p{C} regex takes care of all non-printable characters. Be aware that this includes tabs and newlines.

As for Emoji characters, that a bit more complicated. You could just match the newer Emoji characters in Unicode, ie Unicode Block 'Emoticons' (U+1F600 to U+1F64F), but that's not really all the Emoji characters, eg ❤ 'HEAVY BLACK HEART' (U+2764) is not in that range.

If you look at those Emoji characters, eg 😀 'GRINNING FACE' (U+1F600), you'll see that it belongs to Unicode Category " Symbol, Other [So] ", which consists of 5855 characters. If you're ok removing all those, that would definitely be the easiest solution.

Your text included a red heart (❤️), not a black heart (❤), and that is done in Unicode by adding a variation selector after the black heart, eg a 'VARIATION SELECTOR-16' (U+FE0F) in this case. There are 256 variation selectors, and they are all in category Mark, Nonspacing [Mn] , but you probably don't want to remove all 1763 of those, so you need to remove the 2 ranges of variation selectors, ie U+FE00 to U+FE0F (selectors 1-16) and U+E0100 to U+E01EF (selectors 17-256).

After that, you may or may not want to reduce consecutive spaces to a single space.

str = str.replaceAll("[\\p{C}\\p{So}\uFE00-\uFE0F\\x{E0100}-\\x{E01EF}]+", "")
         .replaceAll(" {2,}", " ");