A set of double-byte charsets in ExtendedCharsets package (sun.nio.cs.ext) has the
following similar implementation model

public class CharsetXYZ extends Charset {
...
    public String getDecoderIndex2() {
        return Decoder.index2;
    }
    public String getEncoderIndex2() {
        return Encoder.Index2;
    }
    private static class Decoder extends XYZDecoder {
        private final static String index2 = "HUGE STRING CONSTANT 1";
        ...
    }
    private static class Encoder extends XYZEncoder {
        private final static String index2 = "HUGE STRING CONSTANT 2";
        ...
    }
...
}

The getDecoderIndex2() and getCoderIndex2() are utility methods used to share
the huge String data with corresponding converter implementation in sun.io package,
they are supposed to save the space for both runtime and static storage (in jar file)
when two implementations (sun.nio.cs.ext and sun.io) share the same data. However,
the above implemention model has a loophole that total fails the expectation, since
the De/Encoder.index2 is a "final" and "static" String, the javac will make a
copy instead of using the reference of De/Encoder.index2 into CharsetXYZ.class,
the result is the size of the supposedly lightweight class CharsetXYZ.class becomes
unreasonable huge (including two huge copies of De/Encoder.index2).

Below is the list of the charsets in charsets.jar that has the overweight
charset class size.

Either to remove the keyword "final" from the String constant declaration or
to "reorg" the declaration as

private final static String index2;
static {
    index2 = "HUGE STRING CONSTNT2"
}

yields a surprising 1.1MB decrease in size out of the 4.6MB charsets.jar.

   297551 EUC_TW$Decoder.class
   486384 EUC_TW$Encoder.class
   468722 EUC_TW.class

    47562 IBM1381$Decoder.class
    67448 IBM1381$Encoder.class
    80838 IBM1381.class

    27037 IBM1383$Decoder.class
    65805 IBM1383$Encoder.class
    76730 IBM1383.class

    57450 IBM33722$Decoder.class
   113585 IBM33722$Encoder.class
   151495 IBM33722.class

    45223 IBM930$Decoder.class
    77387 IBM930$Encoder.class
    98091 IBM930.class

    91826 IBM933$Decoder.class
   130404 IBM933$Encoder.class
    59788 IBM933.class

    39135 IBM935$Decoder.class
    67545 IBM935$Encoder.class
    82161 IBM935.class

    72513 IBM937$Decoder.class
    85852 IBM937$Encoder.class
   142030 IBM937.class

    45223 IBM939$Decoder.class
    77386 IBM939$Encoder.class
    98090 IBM939.class

    38683 IBM942$Decoder.class
    69778 IBM942$Encoder.class
    82680 IBM942.class
    17292 IBM942C$Encoder.class

    39149 IBM943$Decoder.class
    68398 IBM943$Encoder.class
    90800 IBM943.class
    25827 IBM943C$Encoder.class

    74150 IBM948$Decoder.class
    85592 IBM948$Encoder.class
   141632 IBM948.class

    80623 IBM950$Decoder.class
    85592 IBM950$Encoder.class
   139913 IBM950.class

   110046 IBM964$Decoder.class
   156843 IBM964$Encoder.class
   255762 IBM964.class

    27011 IBM970$Decoder.class
   121104 IBM970$Encoder.class
    77734 IBM970.class