Possible, but not practical.
Without a book, your best place to start is the Java Tutorial:  
http://java.sun.com/docs/books/tutorial/

You will also note in the API docs (such as the package javax.swing) once  
you scroll past the classes and read the "Package javax.swing Description"  
it will refer you to the Java Tutorial. API docs are intended to be a  
quick reference once you have a general idea what you are looking for. For  
small packages that have a very well defined meaning, then the API docs  
may be sufficient, but for more sophisticated packages (such as Swing),  
you are better off reading the package tutorial to get a feel for the  
terminology and structure.

There are a number of books available though, so it might not hurt to pick  
up one for reading.

HTH,

-Zig