Why did my java program compile but not run?

Question

Java

There was code in Head First Java 2nd Edition by Kathy Sierra, Bert Bates in Chapter 11 that I copied and pasted to myself. I compiled it without problems, but when I run it, the command line gives me could not find or load main class. What to do, and why the program does not start? Maybe it has something to do with the java version?

Answer 1

link
chapter "Writing a program Hello, World!", everything is shown and described how and why exactly to compile and run it through the command line. Better yet, read it in its entirety.