If we issue a command like

java Hello

it implies we take it as an Java Application. It should have a main(String args[]) method as
an entry point. The code you mentioned, I guess because I don't have a copy of Thinking in Java, has No main() methods.
So this you cannot run it by issuing a command like


java AllOps

If you do that, JVM will examine the byte-code. Once it goes throught the byte-code and does not foind main() method, it throws the error you cited here.

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godd luck.