One of the most common questions I see on mailing lists and forums related
to Java internationalization is “Why can’t my applet display Japanese and
Chinese text when my native applications can?”
Well, if you’re using JDK 5.0, the famous “Tiger” release, there’s a
good chance you don’t need to ask this question anymore. That’s because
this release supports multilingual font rendering. Multi-what?
OK, let’s look at a demo first – here’s one that comes with the JDK: Font2DTest.
Here’s Font2DTest running on J2RE 1.4.2 with English as the user language
on Windows XP. The “CJK Unified Ideographs” characters are selected, the
collection of basic Chinese (“C”) characters that are also used for
Japanese (“J”) and Korean (“K”).
We see: Lots of empty boxes, indicating that the Java runtime in this
environment can’t display Chinese characters. Let’s try the same with Japanese
as the user language:
Well, that looks slightly better. The number of empty boxes has decreased
significantly, and real characters have taken their place. The reason for
the remaining empty boxes is that the CJK Unified Ideographs block contains
the union of the basic characters used with Chinese, Japanese, and Korean.
When running in a Japanese environment, JRE 1.4.2 finds glyphs for Japanese
characters, but not for characters that are only used for Chinese or Korean.
Now, let’s see what happens with the mighty Tiger. And let’s try the most
difficult environment first – plain English.
No more boxes! This is what we mean by “multilingual font rendering” –
all languages together in one big happy application.
Would running in a Japanese environment still make a difference? In fact,
it would:
If you look closely, you’ll see that some of the glyphs look different
between the two screen shots. That’s because in a Japanese environment
the JRE gives preference to Japanese fonts (and in a Korean environment
to Korean fonts), while in other environments it prefers Chinese fonts.
In which situations does your application benefit from this feature? Well,
first the host OS needs to have the necessary fonts installed. Most operating
systems these days come with fonts for a
long list of European and Asian languages; you just have to ask for
them during installation or through a control panel such as the “Regional
and Language Options” in Windows XP. Then, your application has to use
Swing components or the Java 2D APIs for font rendering. If it uses AWT,
results vary. One place where Swing applications may still see problems
are window titles, because these are typically rendered using AWT. Finally,
the application should use logical fonts – that’s Serif, SansSerif, Monospaced,
Dialog, and DialogInput. If it uses a physical font, it gets the glyphs
provided by that font, and nothing else.
There’s more information on related issues in the Internationalization
FAQ. But at least for this question there’s now an easy answer: Get
Tiger!
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