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Take a look at the java tutorial. Go to this site and Find Generics:
The Really Big Index

The message deals with Generics, a way to have the compiler check the types of objects you use with various classes.

Here is the command line I use for compiling with some sample compiler options:
F:\Java\jdk1.6.0_29\bin\javac.exe -Xlint -g -deprecation -classpath D:\JavaDevelopment\;.;..\....