Improving API documentation using API usage information

Jadeite is a new Javadoc-like API documentation system that takes advantage of multiple users' aggregate experience to reduce difficulties that programmers have learning new APIs. Previous studies have shown that programmers often guessed that certain classes or methods should exist, and looked for these in the API. Jadeite's ldquoplaceholdersrdquo let users add new ldquopretendrdquo classes or methods that are displayed in the actual API documentation, and can be annotated with the appropriate APIs to use instead. Since studies showed that programmers had difficulty finding the right classes from long lists in documentation, Jadeite takes advantage of usage statistics to display commonly used classes more prominently. Programmers had difficulty discovering how to instantiate objects, so Jadeite uses a large corpus of sample code to automatically the most common ways to construct an instance of any given class. An evaluation showed that programmers were about three times faster at performing common tasks with Jadeite than with standard Javadoc.