jiff.sh

#!/bin/bash
jarfile1=$1
jarfile2=$2
tmpdir=`mktemp -d -t jiff-XXX`
echo $tmpdir
mkdir -p $tmpdir/{dir1,dir2}
cp $jarfile1 $tmpdir/dir1
cp $jarfile2 $tmpdir/dir2
cd $tmpdir/dir1
jar xvf $(basename $jarfile1)
for i in `find $tmpdir/dir1 -name "*.class"`
do
    javap $i > ${i}.txt #list the functions/variables etc
done

cd $tmpdir/dir2
jar xvf $(basename $jarfile2)
for i in `find $tmpdir/dir2 -name "*.class"`
do
    javap $i > ${i}.txt #list the functions/variables etc
done

diff -r $tmpdir/dir1 $tmpdir/dir2