Limits to Swing's Unicode support

Question

Not long ago I asked a question attempting to identify a certain unicode character for use in a GUI. I got the character I was looking for, but it didn't work in the Swing GUI I was building.

So, SO Community, I pose of you these questions:

What sort of limitations does Swing/Java have for Unicode support? Are there certain subsets of unicode that are completely supported and what should I stay away from when designing in the future?

EDIT: After applying the 'Arial Unicode MS' font as suggested by Alan Moore, everything seemed to clear up. Seems odd that I should have to set a 3rd party font to make all the unicode characters show up though.

Answer 1

Normally when glyphs don't display properly in a UI, it's because you're using a font that doesn't have that glyph, not because there is a problem with the unicode support in any toolkit you're using. Very, VERY few fonts have all glyphs - you need to make sure you choose a font that has coverage in the code points you care about.

Answer 2

Java 1.6 should have support for all Unicode characters. IIRC 1.5 didn't have methods to handle multi-char UTF-16 characters (new APIs were added to 1.6).

The characters from the question you posted show up just fine in the Java editor I use. Make sure the font you're using supports that character; the built-in JDK fonts support a lot of characters, but definitely not all. Take a look at the java.awt.Font.canDisplay() methods.

Answer 3

See Sun Java 6 fonts Supported Fonts for details on the limitations of the logical fonts. Sun's choices were probably due to a mixture of pragmatism and licensing. Note that the documentation says you can provision fallback fonts by adding them to the JRE lib/fonts/fallback directory.