That's because Object is a regular class and arrays are a special language feature as I said above. The API documentation only contains the documentation for Java classes. Other language feature like the Java keywords are missing in the API doc, too. It's a simple fact that they are documented elsewhere and it is not theory. There are tons of specifications and documentations for Java which decribe the language parts you are missing in the API doc. The Java language specification (JLS) is one important additional documentation.