Handling Events - Beginning Java 2 SDK - page 767

Adding the toolbar itself couldn't be easier. A toolbar is a Swing component defined by the JToolBar
class. You can add a member to the SketchFrame class for a toolbar by adding the following field to
the class definition:
private JToolBar toolBar = new JToolBar(); // Window toolbar
You can position this following the declaration of the menuBar member. It simply creates a JToolBar
object as a member of the class. To add it to the frame window, you need to add the following statement
after the existing code in the SketchFrame constructor:
getContentPane().add(toolBar, BorderLayout.NORTH);
This adds the (empty) toolbar to the top of the content pane for the frame window. The content pane has the
BorderLayout manager as the default, which is very convenient. A JToolBar object should be added to a
Container using the BorderLayout manager since it is normally positioned at one of the four sides of a
component. An empty toolbar is not much use though, so let's see how to add buttons.
Adding Buttons to a Toolbar
The JToolBar class inherits the add() methods from the Container class, so you could create JButton
objects and add them to the toolbar. However, since a toolbar almost always has buttons corresponding to
menu functions, a much better way is to use the add() method defined in the JToolBar class to add an
Action object to the toolbar. We can use this to add any of the Action objects that we created for our
menus, and have the toolbar button events taken care of without any further work.
For example, we could add a button for the openAction object corresponding to the Open menu item
in the File menu with the statement:
toolBar.add(openAction); // Add a toolbar button
That's all you need basically. The add() method will create a JButton object based on the Action
object passed as the argument. A reference to the JButton object is returned in case you want to store
it to manipulate it in some way - adding a border for instance. Let's see how that looks.
Try It Out - Adding a Toolbar Button
Assuming you have added the declaration for the toolBar object to the SketchFrame class, you just
need to add a couple of statements preceding the last statement in the constructor to add the toolbar to
the content pane:
public SketchFrame(String title) {
// Constructor code as before...
JButton button = toolBar.add(openAction); // Add toolbar button
button.setBorder(BorderFactory.createRaisedBevelBorder()); // Add button border
getContentPane().add(toolBar, BorderLayout.NORTH); // Add the toolbar
}