GUI Construction

1. GUI Construction
A Java technology GUI can be created using either of the following techniques.
• Programmatic construction
This technique use code to create the GUI. This technique is used for learning GUI construction. However, it is very laborious to use in production environment.
• Construction using a GUI builder tool
This technique uses a GUI builder tool to create the GUI. The GUI developer uses a visual approach to drag-and-drop containers and components to a work area.
2. Example of programmatic construction
This sections a simple GUI that prints a Hello World. The code shown in below create a container JFrame with a title HelloWorldSwing. It later adds a JLabel with the Accessible Name property set to Hello World.
3. Key Methods
Methods for setting up the JFrame and adding JLabel:
• setDefaultCloseOperationJFrame.EXIT_ON_CLOSE)
–Creates the program to exit when the close button is clicked. There are four possible ways of handling this:
a. DO_NOTHING_ON_CLOSE: does nothing when the close operation is initiated. This constant is defined in WindowsConstants.
b. Hide_ON_ClOSE: invokes any WindowListener objects and hides the frame. This constant is defined in WindowsConstants.
c. DISPOSE_ON_CLOSE: invokes any WindowListener objects and hides and disposes the frame. This constant is defined in WindowsConstants.

• setVisible(true)– Makes the JFrame visible.
• add(Component c)– this method adds the components to the container.

To handle these tasks efficiently the Swing framework uses threads that are light-weight process . The tasks described can be handled by these threads separately and concurrently.
The programmer should utilities these threads. The Swing framework provides a collection of utility methods in the SwingUtilities class.
SwingUtilites.invokeLater(new Runnable())

In the java programming language, threads are created using the Runnable interface. This interface defines a method run that should be implemented by all the classes using this interface. The invokeLater method schedule the GUI creations taks to execute the run method a synchronously by the event-handling thread after all the pending events are completed.