Address various warnings in source files.

First batch of resolved warnings in various Java source files.
Warnings not removed include deprecation issues and typecasting warnings.

---

Please take quick a look at the corrections I made to get rid of these warnings. They didn't add any errors, and I'm still able to run things fine in the child Eclipse, so I think everything should be okay.

If there aren't any problems, I'll continue working on fixing warnings.