You can browse the Javadoc documentation of the JDK from the IDE. In the Explorer, click on the Javadoc tab. Then right-click the Javadoc node and choose Add Directory from the contextual menu. In the file chooser, navigate to the JDK documentation and select the 'docs' directory. Then you can choose View | Javadoc Index Search or press Ctrl-F1 on a class in the Source Editor to view the documentation.