The javac compiler always looks for files in the current directory, but the java interpreter only looks into the current directory if the "." directory is on the class path. If you have no class path set, this is not a problem—the default class path consists of the "." directory. But if you have set the class path and forgot to include the "." directory, then your programs will compile without error, but they won't run.

Features tagged as public can be used by any class. Private features can be used only by the class that defines them. If you don't specify either public or private, then the feature (that is, the class, method, or variable) can be accessed by all methods in the same package.

Comment Extraction

Here, docDirectory is the name of the directory where you want the HTML files to go. Follow these steps:

1.	Change to the directory that contains the source files you want to document. If you have nested packages to document, such as com.horstmann.corejava, you must be working in the directory that contains the subdirectory com. (This is the directory that contains the overview.html file if you supplied one.)
2.	Run the command javadoc -d docDirectory nameOfPackage for a single package. Or run javadoc -d docDirectory nameOfPackage1 nameOfPackage2... to document multiple packages. If your files are in the default package, then instead run javadoc -d docDirectory *.java