These are notes from Dima about how he shrunk down java to about 30 MB. It isn't stated here in the notes but I believe he started with java 1.4.2
We had problems getting java 1.5 to work on the OLPC. See the parent page for more notes on just getting Sun's Java to run: OLPC Dimas work

To use our software effectively we need a working version of Webstart (Java's web launching system). And as of the last check the only form of Java that included this was from Sun.

currently all java install takes 52MB of disk space
du output:
du /usr/local/java
....
51828 /usr/local/java

after removing plugin.jar it became ~50MB
I removed lib/i386/server folder (~7.5M)
and 2 small folders man and plugin
concord jnlp works fine
and size of the java folder is ~41.5M
original rt.jar has size ~22M
interesting that rt.jar has uncompressed files
so I unjar content of rt.jar
and created rt.jar with the command jar cf rt.jar *
in result I got workable rt.jar with size 11.5M
so currently java folder has size 29686K
df output is:
Filesystem 1K-blocks Used Available Use% Mounted on
/def/hda1 476913 398324 73665 85% /

after removing com/sun/corba classes
I got size of the java folder 28891K and I have amount available blocks 74462

I removed few fonts from the lib/fonts folder:
LucidaBright*.ttf
and
LucidaTypewriter*.ttf
it gave us another 1.2MB

also I created new rt.jar without java/sql and sun/jdbc
after jar we have another 0.15MB (not much but still)

additionally
I removed /com/sun/java/plaf/gtk
and
/com/sun/java/plaf/windows
packages
see attachment rt3.jar
upload it to OLPC image rename to rt.jar and put it to /usr/local/java/j2re.../lib/
folder (yet another 0.8MB)