The Java 1.0 platform was limited to displaying only the characters in the ISO-Latin-1 subset of Unicode. This restriction was removed in the Java 1.1 platform. Java programs running on 1.1 or 1.2 can display any Unicode character which can be rendered with a host font.

The runtime provides a small number of predefined "virtual" font names, and maps them to real fonts available on the host. In 1.0, each Java font name mapped to exactly one host font. In 1.1 and 1.2, a Java font name can map to a series of host fonts, which can be chosen to cover as much of the Unicode character set as is desired. The font mapping is specified in a font properties file.

Since Java font names are virtual names that can represent multiple host fonts, it is appropriate that they have generic names. JDK 1.0 included the font names TimesRoman, Courier, and Helvetica, which were very specific and do not apply to many locales. JDK 1.1 introduced three replacements for these names: Serif, SansSerif, and MonoSpaced. Use of these new names is recommended.

The JDK ships with font property files that cover all supported locales. For a locale to be supported, an adequate font property file must exist.

Font Property File

#-------------------------------------------
serif.0.plain=Times New Roman
serif.1.plain=MS Mincho
# Any style fonts use WinDings as component font 2
# and Lucida Sans Unicode Regular as component font 3.
serif.2=WingDings
serif.3=Lucida Sans Unicode Regular
...
sansserif.0.italic=Helvetica
sansserif.1.italic=MS Gothic
....
....
#-------------------------------------------

The complete key representation is:

<abstract name>.<component font number>.<style name>.

The font properties file can also specify a default character to be displayed in place of characters that can not be rendered with the given mappings. The default character is specified in terms of its Unicode value, as shown below. If the default character can not be mapped, the ASCII `?' is used.

#-----------------------------------

default.char=274f

#-----------------------------------

#--------------------------------

alias.timesroman=serif

alias.helvetica=sansserif

alias.courier=monospaced

#-----------------------------------

#---------------------------------------

exclusion.sansserif.1=xxxx-XXXX

exclusion.monospaced.plain.2=xxxx-XXXX

#---------------------------------------

Supporting User-Defined Characters

For example, assume a user has a font which contains exactly three glyphs. The glyphs are indexed 0, 1, and 2 in the font, and the user wishes to map these into the Unicode characters \uE800, \uE801, \uE802 (three Private Use Area characters in Unicode). This can be accomplished with the following two steps:

1. Subclass CharToByteConvertor (or one of its subclasses).

class MyFontCharset extends CharToByteSingleByte {
	private String name;

	public MyFontCharset(){
		name = "MyGaiji";
	}

	public boolean isConvert(char ch){
		if (ch >= 0xE800 && ch <= 0xE802)
			return true;
		else
			return false;
	}

	// this is the conversion method actually called by 
	// the font mechanism
	public int convert(String str, byte[] out){
		for (int i = 0; i < str.length(); i++){
			out[i] = str.charAt(i) - 0xE800;
		}
		return str.length();
	}

	// needed as convert is an abstract method in
	// CharToByteConversion
	public int convert(char ch[],int off,int len, 
			   byte b[], int boff, int blen){
		String str = new String(ch, off, len);
		byte bb[] = new byte[blen-boff];
		System.arraycopy(b,boff,bb,0,bb.length);
		return convert(str, bb);
	}

	public String toString(){
		return name;
	}
}

2. Specify this class in a property as follows:

#------------------------------------------------------------
...
serif.4=<special font name>
...
fontcharset.serif.4=MyFontCharset
...
#----------------------------------------------------------------