Java Unicode String length

Question

I am trying hard to get the count of unicode string and tried various options. Looks like a small problem but struck in a big way.

Here I am trying to get the length of the string str1. I am getting it as 6. But actually it is 3. moving the cursor over the string "குமார்" also shows it as 3 chars.

Basically I want to measure the length and print each character. like "கு", "மா", "ர்" .

 public class one {
    public static void main(String[] args) {
            String str1 = new String("குமார்");
            System.out.print(str1.length());
    }
}

PS : It is tamil language.

Answer 1

Found a solution to your problem.

Based on this SO answer I made a program that uses regex character classes to search for letters that may have optional modifiers. It splits your string into single (combined if necessary) characters and puts them into a list:

import java.util.*;
import java.lang.*;
import java.util.regex.*;

class Main
{
    public static void main (String[] args)
    {
        String s="குமார்";
        List<String> characters=new ArrayList<String>();
        Pattern pat = Pattern.compile("\\p{L}\\p{M}*");
        Matcher matcher = pat.matcher(s);
        while (matcher.find()) {
            characters.add(matcher.group());            
        }

        // Test if we have the right characters and length
        System.out.println(characters);
        System.out.println("String length: " + characters.size());

    }
}

where \\p{L} means a Unicode letter, and \\p{M} means a Unicode mark.

The output of the snippet is:

கு
மா
ர்
String length: 3

See https://ideone.com/Apkapn for a working Demo

---

EDIT

I now checked my regex with all valid Tamil letters taken from the tables in http://en.wikipedia.org/wiki/Tamil_script. I found out that with the current regex we do not capture all letters correctly (every letter in the last row in the Grantha compound table is splitted into two letters), so I refined my regex to the following solution:

Pattern pat = Pattern.compile("\u0B95\u0BCD\u0BB7\\p{M}?|\\p{L}\\p{M}?");

With this Pattern instead of the above one you should be able to split your sentence into every valid Tamil letter (as long as wikipedia's table is complete).

The code I used for checking is the following one:

String s = "ஃஅஆஇஈஉஊஎஏஐஒஓஔக்ககாகிகீகுகூகெகேகைகொகோகௌங்ஙஙாஙிஙீஙுஙூஙெஙேஙைஙொஙோஙௌச்சசாசிசீசுசூசெசேசைசொசோசௌஞ்ஞஞாஞிஞீஞுஞூஞெஞேஞைஞொஞோஞௌட்டடாடிடீடுடூடெடேடைடொடோடௌண்ணணாணிணீணுணூணெணேணைணொணோணௌத்ததாதிதீதுதூதெதேதைதொதோதௌந்நநாநிநீநுநூநெநேநைநொநோநௌப்பபாபிபீபுபூபெபேபைபொபோபௌம்மமாமிமீமுமூமெமேமைமொமோமௌய்யயாயியீயுயூயெயேயையொயோயௌர்ரராரிரீருரூரெரேரைரொரோரௌல்லலாலிலீலுலூலெலேலைலொலோலௌவ்வவாவிவீவுவூவெவேவைவொவோவௌழ்ழழாழிழீழுழூழெழேழைழொழோழௌள்ளளாளிளீளுளூளெளேளைளொளோளௌற்றறாறிறீறுறூறெறேறைறொறோறௌன்னனானினீனுனூனெனேனைனொனோனௌஶ்ஶஶாஶிஶீஶுஶூஶெஶேஶைஶொஶோஶௌஜ்ஜஜாஜிஜீஜுஜூஜெஜேஜைஜொஜோஜௌஷ்ஷஷாஷிஷீஷுஷூஷெஷேஷைஷொஷோஷௌஸ்ஸஸாஸிஸீஸுஸூஸெஸேஸைஸொஸோஸௌஹ்ஹஹாஹிஹீஹுஹூஹெஹேஹைஹொஹோஹௌக்ஷ்க்ஷக்ஷாக்ஷிக்ஷீக்ஷுக்ஷூக்ஷெக்ஷேக்ஷைஷொக்ஷோஷௌ";
List<String> characters = new ArrayList<String>();
Pattern pat = Pattern.compile("\u0B95\u0BCD\u0BB7\\p{M}?|\\p{L}\\p{M}?");
Matcher matcher = pat.matcher(s);
while (matcher.find()) {
    characters.add(matcher.group());
}

System.out.println(characters);
System.out.println(characters.size() == 325);

Answer 2

Have a look at the Normalizer class. There is an explanation of what may be the cause of your problem. In Unicode, you can encode characters in several ways, e.g Á:

  U+00C1    LATIN CAPITAL LETTER A WITH ACUTE

or

  U+0041    LATIN CAPITAL LETTER A
  U+0301    COMBINING ACUTE ACCENT

You can try to use Normalizer to convert your string to the composed form and then iterate over the characters.

---

Edit: Based on the article suggested by @halex above, try this in Java:

    String str = new String("குமார்");

    ArrayList<String> characters = new ArrayList<String>();
    str = Normalizer.normalize(str, Form.NFC);
    StringBuilder charBuffer = new StringBuilder();
    for (int i = 0; i < str.length(); i++) {
        int codePoint = str.codePointAt(i);
        int category = Character.getType(codePoint);
        if (charBuffer.length() > 0
                && category != Character.NON_SPACING_MARK
                && category != Character.COMBINING_SPACING_MARK
                && category != Character.CONTROL
                && category != Character.OTHER_SYMBOL) {
            characters.add(charBuffer.toString());
            charBuffer.delete(0, charBuffer.length());
        }
        charBuffer.appendCodePoint(codePoint);
    }
    if (charBuffer.length() > 0) {
        characters.add(charBuffer.toString());
    }
    System.out.println(characters);

The result I get is [கு, மா, ர்]. If it doesn't work for all your strings, try fiddeling with other Unicode character categories in the if block.

Answer 3

This turns out to be really ugly.... I have debugged your string and it contains following characters (and their hex position):

க 0x0b95
ு 0x0bc1
ம 0x0bae
ா 0x0bbe
ர 0x0bb0
் 0x0bcd

So tamil language obviously use diacritics-like sequences to get all characters which unfortunately count as separate entities.

This is not a problem with UTF-8 / UTF-16 as erronously claimed by other answers, it is inherent in the Unicode encoding of the Tamil language.

The suggested Normalizer does not work, it seems that tamil has been designed by Unicode "experts" to explicitly use combination sequences which cannot be normalized. Aargh.

My next idea is not to count characters, but glyphs, the visual representations of characters.

String str1 = new String(Normalizer.normalize("குமார்", Normalizer.Form.NFC ));

Font display = new Font("SansSerif",Font.PLAIN,12);
GlyphVector vec = display.createGlyphVector(new FontRenderContext(new AffineTransform(),false, false),str1);

System.out.println(vec.getNumGlyphs());
for (int i=0; i<str1.length(); i++)
        System.out.printf("%s %s %s %n",str1.charAt(i),Integer.toHexString((int) str1.charAt(i)),vec.getGlyphVisualBounds(i).getBounds2D().toString());

The result:

க b95 [x=0.0,y=-6.0,w=7.0,h=6.0]
ு bc1 [x=8.0,y=-6.0,w=7.0,h=4.0]
ம bae [x=17.0,y=-6.0,w=6.0,h=6.0]
ா bbe [x=23.0,y=-6.0,w=5.0,h=6.0]
ர bb0 [x=30.0,y=-6.0,w=4.0,h=8.0]
் bcd [x=31.0,y=-9.0,w=1.0,h=2.0]

As the glyphs are intersecting, you need to use Java character type functions like in the other solution.

SOLUTION:

I am using this link: http://www.venkatarangan.com/blog/content/binary/Counting%20Letters%20in%20an%20Unicode%20String.pdf

public static int getTamilStringLength(String tamil) {
    int dependentCharacterLength = 0;
    for (int index = 0; index < tamil.length(); index++) {
        char code = tamil.charAt(index);
        if (code == 0xB82)
            dependentCharacterLength++;
        else if (code >= 0x0BBE && code <= 0x0BC8)
            dependentCharacterLength++;
        else if (code >= 0x0BCA && code <= 0x0BD7)
            dependentCharacterLength++;
    }
    return tamil.length() - dependentCharacterLength;
  }

You need to exclude the combination characters and count them accordingly.

Answer 4

As has been mentioned, your string contains 6 distinct code points. Half of them are letters, the other half are vowel signs. (Combining marks)

You could use transformations built into the ICU4J library, to remove all of the vowel signs which are not Letters using the rule:

[:^Letter:] Remove

and count the resulting string. Try it out on their demo site:

http://demo.icu-project.org/icu-bin/translit

I wouldn't display the resultant string to an end user, and I'm not an expert so the rules may need to be tweaked to get to the general case but it's a thought.

Answer 5

This is the new way to calculate the length of a Java String taking into account the Unicode characters.

int unicodeLength = str.codePointCount(0, str.length);