Swing in Core Java

Swing is a GUI toolkit that facilitates the creation of highly interactive GUI applications. Swing is more flexible and robust when it comes to implementing graphical components.
Swing can be regarded as more graphically-rich than AWT not only because they provide some entirely new graphical components like a tabbed window and tree structure.
Some of the key swing classes are given as below :

Swing Class Description
JAppletIt is an extension of Applet class, it is the swing's version of the applet.
JFrameIt is an extension of java.awt.Frame class, it is the swing's version of the frame.
JButtonIt helps to realize a push button in the swing.
JTabbedPaneIt helps to realize a tabbed pane in the swing.
JTreeIt helps to realize a hierarchical tree or structure in the swing.
JComboBoxIt helps to realize a combo box in the swing.