JFrame

In Java Swing, JFrame is a top-level window that provides a window with a title bar, borders, and standard window controls. It is part of the javax.swing package and serves as a primary top-level container for building graphical user interfaces.

JFrame extends java.awt.Frame and contains a JRootPane which holds a layered pane, a content pane for application components, and an optional glass pane. Components are added to the frame’s content pane via getContentPane() or by calling add, which delegates to the content pane. The content pane is typically a JPanel with a layout manager.

Common operations include setTitle, pack, setSize, setResizable, setLocationRelativeTo, and setVisible. The frame also supports setDefaultCloseOperation with options DO_NOTHING_ON_CLOSE, HIDE_ON_CLOSE, DISPOSE_ON_CLOSE, and EXIT_ON_CLOSE to control behavior when the user closes the window. Frames can also host a menu bar through setJMenuBar and can customize the icon via setIconImage.

Lifecycle: after construction, the frame is configured, then made visible by setVisible(true). Closing the frame disposes of native resources, and if EXIT_ON_CLOSE is set, terminates the application. Best practice is to construct and manipulate Swing components on the Event Dispatch Thread to ensure thread safety and proper UI behavior.

See also: Event Dispatch Thread, Swing, RootPaneContainer.