In original code of the JDK you find the following:
package sun.io;
import sun.nio.cs.MS1252;
public class ByteToCharCp1252 extends ByteToCharSingleByte {
private final static MS1252 nioCoder = new MS1252();
public String getCharacterEncoding() {
return "Cp1252";
}
public ByteToCharCp1252() {
super.byteToCharTable = nioCoder.getDecoderSingleByteMappings();
}
}
At every instantiation of ByteToCharCp1252 every time a MS1252-object
will be instantiated, just only to get the byteToCharTable. Afterwards
the garbage collector may take care about it.
The MS1252 class looks correspondingly:
package sun.nio.cs;
import java.nio.charset.*;
public class MS1252 extends Charset {
public CharsetDecoder newDecoder() {
return new Decoder(this);
}
public String getDecoderSingleByteMappings() {
return Decoder.byteToCharTable;
}
private static class Decoder extends SingleByteDecoder {
public Decoder(Charset cs) {
super(cs, byteToCharTable);
}
private static final String byteToCharTable =
"\u20AC\uFFFD\u201A\u0192\u201E\u2026\u2020\u2021" + //
0x80 - 0x87
"\u02C6\u2030\u0160\u2039\u0152\uFFFD\u017D\uFFFD" + //
0x88 - 0x8F
.......
}
}
I think, we can code this like the following:
package sun.io;
public class ByteToCharCp1252 extends ByteToCharSinglebyte {
public String getCharacterEncoding() {
return "Cp1252";
}
public ByteToCharCp1252() {
super(sun.nio.cs.MS1252.byteToCharTable);
}
.......
}
package sun.nio.cs;
import java.nio.charset.*;
public class MS1252 extends US_ASCII {
public static final String byteToCharTable =
"\u20AC\uFFFD\u201A\u0192\u201E\u2026\u2020\u2021" + // 0x80
- 0x87
"\u02C6\u2030\u0160\u2039\u0152\uFFFD\u017D\uFFFD" + // 0x88
- 0x8F
.......
public CharsetDecoder newDecoder() {
return new Decoder(this, byteToCharTable);
}
private static class Decoder extends SingleByteDecoder {
public Decoder(Charset cs, String byteToCharTable) {
super(cs, byteToCharTable);
}
.......
}
.......
}
... and if we look closely a 2nd time, we will see, that the internal
static Decoder class could be saved also:
package sun.nio.cs;
import java.nio.charset.*;
public class MS1252 extends US_ASCII {
public static final String byteToCharTable =
"\u20AC\uFFFD\u201A\u0192\u201E\u2026\u2020\u2021" + // 0x80
- 0x87
"\u02C6\u2030\u0160\u2039\u0152\uFFFD\u017D\uFFFD" + // 0x88
- 0x8F
.......
public CharsetDecoder newDecoder() {
return new SingleByteDecoder(this, byteToCharTable);
}
.......
}
If we consider, that in each Charset class that way a static Decoder and
a Encoder class could be saved, the amount of classes can be saved to
1/3. This would save both startup-time and footprint of the JVM.
You can watch the progress of my work here:
https://java-nio-charset-enhanced.dev.java.net/
Regards
Ulf Zibis
