The components added to the frame are referred to as its contents; these are managed by the contentPane. To add a component to a JFrame, we must use its contentPane instead. JFrame is a Window with border, title and buttons. When JFrame is set visible, an event dispatching thread is started. JFrame objects store several objects including a Container object known as the content pane. To add a component to a JFrame, add it to the content pane.

Features:

• => It’s a window with title, border, (optional) menu bar and user-specified components.
• => It can be moved, resized, iconified.
• => It is not a subclass of JComponent.
• => Delegates responsibility of managing user-specified components to a content pane, an instance of JPanel.

Centering JFrame’s:

By default, a Jframe is displayed in the upper-left corner of the screen. To display a frame at a specified location, you can use the setLocation(x, y) method in the JFrame class. This method places the upper-left corner of a frame at location (x, y). The Swing API keeps improving with abstractions such as the setDefaultCloseOperation method for the JFrame.

Crating a JFrame Window:

Step 1: Construct an object of the JFrame class.
Step 2: Set the size of the Jframe.
Step 3: Set the title of the Jframe to appear in the title bar
Step 4: Set the default close operation.
Step 5: Make the Jframe visible.

Constructors:

JFrame() - Constructs a new frame that is initially invisible.
JFrame(GraphicsConfiguration gc) - Creates a Frame in the specified GraphicsConfiguration of a screen device and a blank title.
JFrame(String title) - Creates a new, initially invisible Frame with the specified title.
JFrame(String title, GraphicsConfiguration gc) - Creates a JFrame with the specified title and the specified GraphicsConfiguration of a screen device.