To compile a source file, javac needs to find the declaration of every class or interface that is used, extended, or implemented by the code in the source file. This lets javac check that the code has the right to access those classes and interfaces. Rather than specifying the source files of those classes and interfaces explicitly, you can use command-line options to tell javac where to search for their source files. If you have compiled those source files previously, you can use options to tell javac where to search for the corresponding class files. The options, which all have names ending in "path", are described in Standard Options, and further described in Configuring a Compilation and Searching for Module, Package and Type Declarations.