The Java Foundation Classes

Swing is actually one API in the JFC suite of libraries:

AWT

-- basic GUI Toolkit shipped with all versions of JDK. Swing does not reuse any AWT components but does build off some lightweight component facilities

Accessibility

-- interface to alternative user interfaces e.g. audible text readers, braille keyboards may interfaced via this API. All Swing Components support accessibility.

2D API

-- Various painting styles, drawing styles, fonts and colours. Not Part of SWING.

Drag and Drop

-- Click and hold of GUI objects, moving windows or objects etc. Not Part of SWING