apt-get and Update Manager

I was installing FreeMind, a free mind-mapping software which runs on Java. I downloaded the debian package and use 'sudo dpkg -i' to install it. It prompted me for some additional libraries as follows:

thomaslai@ubuntu:~/Desktop$ sudo dpkg -i freemind_0.8.0-1_all.deb
(Reading database ... 85042 files and directories currently installed.)
Preparing to replace freemind 0.8.0-1 (using freemind_0.8.0-1_all.deb) ...
Unpacking replacement freemind ...
dpkg: dependency problems prevent configuration of freemind:
freemind depends on librelaxng-datatype-java; however:
Package librelaxng-datatype-java is not installed.
freemind depends on libcommons-lang-java; however:
Package libcommons-lang-java is not installed.
dpkg: error processing freemind (--install):
dependency problems - leaving unconfigured
Errors were encountered while processing:
freemind


While I was wondering how I could find the dependent libraries, suddenly the Update Manager icon springs to life in system tray in Ubuntu. I click on it, and oh my dear, the 2 missing libraries are prompted in Ubuntu Update Manager for me to download and install!

apt-get is truly amazing!