$ sudo apt-get update
$ sudo apt-get install gcj-6-jre-lib 

gcj-6-jre-lib is installed in your system.

Make ensure the gcj-6-jre-lib package were installed using the commands given below,

$ sudo dpkg-query -l | grep gcj-6-jre-lib *

You will get with gcj-6-jre-lib package name, version, architecture and description in a table

gcj-6-jre-lib package basic information: