C:\robot\temp> dir

10/19/2013  05:24 PM             4,277 Main.class
10/19/2013  05:24 PM             1,965 MtrTester.class


C:\robot\temp> java Main.class

Error: Could not find or load main class Main.class


C:\robot\temp> java MtrTester.class

Error: Could not find or load main class MtrTester.class


C:\robot\temp> java -showversion

java version "1.7.0_25"
Java(TM) SE Runtime Environment (build 1.7.0_25-b17)
Java HotSpot(TM) Client VM (build 23.25-b01, mixed mode, sharing)


C:\robot\temp>