Why am I not able to install libgcj6?

[Josef Lowder]

.
I am trying to install 'pdftk' (pdf tool kit), 
but I am running into one roadblock after another. 

First, I saw this message:
   Some package request cannot be installed:
   pdftk-1.12-2mdk.i586 (due to unsatisfied libgcj.so.6)
   Continue?

So, I went looking for libgcj.so.6
The closest I could find was this:
   libgcj6-4.0.1-5mdk.i586.rpm

When I tried to install this libgcj... 
First, I saw this: 
   You are about to install the following software package on your computer:
   libgcj6-4.0.1-5mdk: GNU Java runtime libraries
   You may prefer to just save it. What is your choice?
   [Install] [Save] [Cancel]

I chose "Install" and then saw this: 
   Some package requested cannot be installed: 
   libgcj6-4.0.1-5mdk.i586 (due to unsatisfied libgcj6-base[==4.0.1])
   Continue?
   [Abort]    [Ok]

What is going on here? 
Why am I not able to install this libgcj6 package?