Learning Java - Chapter 7 : Java : Supplements

In Swing the group of settings for the GUI color scheme, the border designs, etc. is referred to as the Look & Feel. There is a default L&F for a given platform. There are typically some optional ones available. You can design your own custon L&Fs as well.

GridBagAppletV4 shown below is the same as GridBagAppletV4 except for the Look & Feel code displayed in red at the start of the GridBagPanelV4 class. This code first obtains a list describing the L&F available to the JVM and then selects one (hardwired in this case) and installs it.

GridBagLayoutV4
Resources: bluebox.jpg, picButton.jpg, picButtonPressed.jpg, face.gif, redBall.gif, redDot.gif

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.border.*;

/**
  * Our third modification to GridBagLayout involves adding
  * icons to buttons and labels.
**/
public class GridBagAppletV4 extends JApplet{

  public void init () {
    Container content_pane = getContentPane ();

    // Create an instance of the GridBagPanel
    GridBagPanelV4 grid_bag_panel = new GridBagPanelV4 (this);

    // And add it to the applet's panel.
    content_pane.add (grid_bag_panel);
  } // init

} // GridBagAppletv4

/**
  * Create a JPanel with 5 components and use GridBagLayout
  * for the overall layout.
**/
class GridBagPanelV4 extends JPanel {
  GridBagConstraints constraints = new GridBagConstraints ();

  // The Insets constructor setting are passed as follows:
  // Insets(int top, int left, int bottom, int right)
  static final Insets fInsets = new Insets(2,2,2,2);

  // Need a reference back to the applet to use it for getting images.
  JApplet fApplet;

  GridBagPanelV3 (JApplet applet) {

  GridBagPanelV4 (JApplet applet) {

    // Get the available Look and Feels.
    UIManager.LookAndFeelInfo [] lanf =
      UIManager.getInstalledLookAndFeels ();

    // Print out the list of L&Fs
    for (int i=0; i < lanf.length; i++) {
       System.out.println (i+". L&F installed = " +lanf[i].getName ());
    }

    // Hard-wired selection of the L&F
    int L_AND_F_Select = 1; // Select one of the Look and Feels

    // Set the chosen L&F
    try {
      UIManager.setLookAndFeel (
          //UIManager.getCrossPlatformLookAndFeelClassName ()
          //new javax.swing.plaf.metal.MetalLookAndFeel ()
          //UIManager.getSystemLookAndFeelClassName()
          lanf [L_AND_F_Select].getClassName ()
        );
    }
    catch (Exception e) {
       System.out.println ("Set L&F error!");
    }

  ... Rest same as GridBagPanelV3 ..

There are a number of other enhancements available to the GUI designer. You can, for example, do custom painting of components if techniques like displaying an icon is not satisfactory. See the Performing Custom Painting - Sun Java Tutorial for more info.

You can also add tool tips to components. These are messages that float above a component when the cursor hovers above it. See How to Use Tool Tips - Sun Java Tutorial.

In Chapter 23: System Properties we discuss how to access the various local graphics settings in case you want to tune your program's display to harmonize your UI with local platforms.