How to classify Japanese characters as either kanji or kana?

Question

Given the text below, how can I classify each character as kana or kanji?

誰か確認上記これらのフ

To get some thing like this

誰 - kanji
か - kana
確 - kanji
認          


        

Answer 1

This seems like it'd be an interesting use for Guava's CharMatcher class. Using the tables linked in Jack's answer, I created this:

public class JapaneseCharMatchers {
  public static final CharMatcher HIRAGANA = 
      CharMatcher.inRange((char) 0x3040, (char) 0x309f);

  public static final CharMatcher KATAKANA = 
      CharMatcher.inRange((char) 0x30a0, (char) 0x30ff);

  public static final CharMatcher KANA = HIRAGANA.or(KATAKANA);

  public static final CharMatcher KANJI = 
      CharMatcher.inRange((char) 0x4e00, (char) 0x9faf);

  public static void main(String[] args) {
    test("誰か確認上記これらのフ");
  }

  private static void test(String string) {
    System.out.println(string);
    System.out.println("Hiragana: " + HIRAGANA.retainFrom(string));
    System.out.println("Katakana: " + KATAKANA.retainFrom(string));
    System.out.println("Kana: " + KANA.retainFrom(string));
    System.out.println("Kanji: " + KANJI.retainFrom(string));
  }
}

Running this prints the expected:

誰か確認上記これらのフ

Hiragana: かこれらの

Katakana: フ

Kana: かこれらのフ

Kanji: 誰確認上記

This gives you a lot of power for working with Japanese text by defining the rules for determining if a character is in one of these groups in an object that can not only do a lot of useful things itself, but can also be used with other APIs such as Guava's Splitter class.

Edit:

Based on jleedev's answer, you could also write a method like:

public static CharMatcher inUnicodeBlock(final Character.UnicodeBlock block) {
  return new CharMatcher() {
    public boolean matches(char c) {
      return Character.UnicodeBlock.of(c) == block;
    }
  };
}

and use it like:

CharMatcher HIRAGANA = inUnicodeBlock(Character.UnicodeBlock.HIRAGANA);

I think this might be a bit slower than the other version though.