Java Swing Tutorial Explaining the JFrame class. 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.
JFrame 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 (title bar will be blank if no title is set).
Step 4: Set the default close operation. When the user clicks the close button, the program stops running.
Step 5: Make the Jframe visible.
How to position JFrame on Screen?
frame.setLocationRelativeTo( null );
JFrame Source Code
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class JFrameDemo {
public static void main(String s[]) {
JFrame frame = new JFrame("JFrame Source Demo");
// Add a window listner for close button
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
// This is an empty content area in the frame
JLabel jlbempty = new JLabel("");
jlbempty.setPreferredSize(new Dimension(175, 100));
frame.getContentPane().add(jlbempty, BorderLayout.CENTER);
frame.pack();
frame.setVisible(true);
}
} |
Output
Java JFrame Hierarchy
javax.swing
Class JFrame
java.lang.Object
java.awt.Component
java.awt.Container
java.awt.Window
java.awt.Frame
javax.swing.JFrame
All Implemented Interfaces:
Accessible, ImageObserver, MenuContainer, RootPaneContainer, Serializable, WindowConstants
JFrame Constructor
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.
