use File::Find;

find ({
    'wanted'            =>  \&processfile,
    'follow'            =>  0
}, '/');

sub processfile {
    my ($dev, $ino, $mode, $nlink, $uid, $gid);
    return unless (($dev, $ino, $mode, $nlink, $uid, $gid) = lstat($_));
    return unless -f _ && -r _ && /^.*\.java\z/si;

    ...
};