o packagelistLoc is the path or URL to the directory containing the package-list file for the external documentation. This can be a URL (http: or file:) or file path, and can be absolute or relative. If relative, make it relative to the current directory from where javadoc was run. Do not include the package-list filename. You can specify multiple -linkoffline options in a given javadoc run. (Prior to 1.2.2, it could be specified only once.) Example using absolute links to the external docs - Let us say you want to link to the java.lang, java.io and other Java SE Platform packages at http://docs.oracle.com/javase/7/docs/api/, but your shell does not have web access. You could open the package-list file in a browser at http://docs.oracle.com/javase/7/docs/api/package-list @ http://docs.oracle.com/javase/7/docs/api/package-list, save it to a local directory, and point to this local copy with the second argument, packagelistLoc. In this example, the package list file has been saved to the current directory "." . The following command generates documentation for the package com.mypackage with links to the Java SE Platform packages. The generated documentation will contain links to the Object class, for example, in the class trees. (Other necessary options, such as -sourcepath, are not shown.) % javadoc -linkoffline http://docs.oracle.com/javase/7/docs/api/ . com.mypackage Example using relative links to the external docs - It's not very common to use -linkoffline with relative paths, for the simple reason that -link usually suffices. When using -linkoffline, the package-list file is generally local, and when using relative links, the file you are linking to is also generally local. So it is usually unnecessary to give a different path for the two arguments to -linkoffline. When the two arguments are identical, you can use -link. See the -link relative example. Manually Creating a package-list File - If a package-list file does not yet exist, but you know what package names your document will link to, you can create your own copy of this file by hand and specify its path with packagelistLoc. An example would be the previous case where the package list for com.spipackage did not exist when com.apipackage was first generated. This technique is useful when you need to generate documentation that links to new external documentation whose package names you know, but which is not yet published. This is also a way of creating package-list files for packages generated with Javadoc 1.0 or 1.1, where package-list files were not generated. Likewise, two companies can share their unpublished package-list files, enabling them to release their cross-linked documentation simultaneously. Linking to Multiple Documents - You can include -linkoffline once for each generated document you want to refer to (each option is shown on a separate line for clarity): % javadoc -linkoffline extdocURL1 packagelistLoc1 \ -linkoffline extdocURL2 packagelistLoc2 \ ... Updating docs - Another use for -linkoffline option is useful if your project has dozens or hundreds of packages, if you have already run javadoc on the entire tree, and now, in a separate run, you want to quickly make some small changes and re-run javadoc on just a small portion of the source tree. This is somewhat of a hack in that it works properly only if your changes are only to doc comments and not to declarations. If you were to add, remove or change any declarations from the source code, then broken links could show up in the index, package tree, inherited member lists, use page, and other places. First, you create a new destination directory (call it update) for this new small run. Let us say the original destination directory was named html. In the simplest example, cd to the parent of html. Set the first argument of -linkoffline to the current directory "." and set the second argument to the relative path to html, where it can find package-list, and pass in only the package names of the packages you want to update: % javadoc -d update -linkoffline . html com.mypackage When the Javadoc tool is done, copy these generated class pages in update/com/package (not the overview or index), over the original files in html/com/package.