Other Details

The application by now is able to accept input from the user, simulate a model, and display results graphically as well as numerical results.

In order to finalize the model, add some additional features to the application. At the end, there is a short description of things that remains to be done.

Adding a Menu

A menu is usually added.

1	Add implements ActionListener to the definition of the BeamModelDemo class such that the first line of the class definition reads

public class BeamModelDemo implements ActionListener {

2	Add a method that handles the event when the user performs actions with the menus. Here an action is added that can be used to exit the application and an about box is added that utilizes one of the JOptionPane dialog boxes.

public void actionPerformed(ActionEvent e) {

  String ac = e.getActionCommand();

  if (ac.equals("exit")) {

    System.exit(0);

  }

  else if (ac.equals("about")) {

    JOptionPane.showMessageDialog(frame,

    "Beam GUI Example\n"+

    "Simple DEMO example\n"+

    "Copyright 2011-2013",

    "About",

    JOptionPane.DEFAULT_OPTION);

  }

}

3	Add a method that defines the menu and menu items. The code adds a File and a Help menu where the exit and about actions are placed as menu items.

private JMenuBar menu() {

  JMenuBar menubar = new JMenuBar();

 

  JMenu menu = new JMenu("File");

  menubar.add(menu);

 

  JMenuItem item = new JMenuItem("Exit");

  item.setActionCommand("exit");

  item.addActionListener(this);

  menu.add(item);

 

  menu = new JMenu("Help");

  menubar.add(menu);

 

  item = new JMenuItem("About");

  item.setActionCommand("about");

  item.addActionListener(this);

  menu.add(item);

 

  return menubar;

}

4	Add a call to menu in the start method just before the call to setVisible:

JMenuBar menubar = menu();

frame.setJMenuBar(menubar);

5	Start the application

Adding an Icon and an Image

An application that has to be used by other people should have appealing appearance and graphics and a suitable icon. For this application add the COMSOL logo to the window. Choose any icon you want to use for your own application.

1	Add a setIcon method to the BeamModelDemo class

private void setIcon(String filename) {

  BufferedImage img;

  img = null;

  try {

    img = ImageIO.read(new File(filename));

  } catch (IOException e) {

    return;

  }

  frame.setIconImage(img);

}

2	Add this line to the top of the start method (right after the call to setSize)

setIcon("comsolicon.png");

3	Place the icon file comsolicon.png in your workspace directory for this project. Right-click BeamModelDemo.java in the Package Explorer and choose Properties in order to determine the location of this directory.

4	It is convenient to have an image that describes the parameters used in the panel on the left side of the window. Start by adding the ImageComponent.java file to the project by dragging it to the src folder in the Package Explorer.

5	Add these lines to the leftPanel method just before the line with return panel;

ImageComponent img =

  new ImageComponent("beam_dim_small.png");

panel.add(img, "span");

6	Place the beam_dim_small.png file in the workspace directory for this project.

7	Start the application.

Look and Feel

The appearance of a Java® Swing application by default does not look like other applications that are written specifically for the platform you are running on. You can improve the appearance by setting the Look and Feel for the Java application:

1	Add a lookandfeel method to the BeamModelDemo class:

private void lookandfeel() {

 try {

  UIManager.setLookAndFeel(

   UIManager.getSystemLookAndFeelClassName());

  }

  catch (Exception e) {

  }

}

2	Add a call to lookandfeel at the very top of the start method

lookandfeel();

3	Run the application. The application demonstration example is now complete.

Finishing Notes

The demonstration example is not an application that is ready to be sent to customers. For further development of the application, consider adding the following functionality:

•	Error handling such that the application becomes insensitive to user’s incorrect input and such that proper error messages are displayed in the event of an error or malfunction.

•	For long running jobs, show an hour glass mouse pointer to show users that a time consuming task has started.

•	The model object keeps the history that is recorded every time the model object is changed such that a model file for Java later can be saved that includes all actions on the object. If that is not required the history generation can be switched off, which saves memory.

•	It is possible to have more than one model in an application. For example, it is possible to add a 3D beam model that utilizes the values calculated by the demonstration application.

•	The graphics window can show 1D, 2D, and 3D graphics, so any results obtained in COMSOL Multiphysics can be shown in your own applications.

•	Code can be added that remembers the choices made in the program. For example, to remember the location of the main window and the values entered in the fields.

•	On-line help is missing.

•	Calculated values could be copied to the clipboard or saved as a text file for easy sharing of the values.