The examples in the programmer's guide have been updated to conform to the new applet API in our 1.0.2 Java Development Kit (JDK). "Superclass not found" error messages are typical if you try to compile Java 1.0 beta code with an alpha version of javac. The recommended fix is to download a copy of the JDK software, and do all further development with that.
Another potential source of this error message is incorrect capitalization of either the file name or the class name in in the file. The Java technology system is case-sensitive, so a HelloWorld class is different from a helloWorld class, and so on.
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