Building graphical user interfaces - Objects First with Java: A Practical Introduction Using BlueJ - page 407

Exercise 11.53 What is a slider ? Find a description and summarize. Give a short example
in Java code about creating and using a slider.
Exercise 11.54 What is a tabbed pane ? Find a description and summarize. Give examples
of what a tabbed pane might be used for.
Exercise 11.55 What is a spinner ? Find a description and summarize.
Exercise 11.56 Find the demo application ProgressBarDemo . Run it on your computer.
Describe what it does.
This is where we shall leave the discussion of the image-viewer example. It can, however, be
extended in many directions by interested readers. Using the information from the online tuto-
rial, you can add numerous interface components.
The following exercises give you some ideas, and obviously there are many more possibilities.
Exercise 11.57 Implement an undo function in your image viewer. This function reverses
the last operation.
Exercise 11.58 Disable all menu items that cannot be used when no image is being displayed.
Exercise 11.59 Implement a reload function that discards all changes to the current image
and reloads it from disk.
Exercise 11.60 The JMenu class is actually a subclass of JMenuItem . This means that
nested menus can be created by placing one JMenu inside another. Add an Adjust menu to
the menu bar. Nest within it a Rotate menu that allows the image to be rotated either 90 or 180
degrees, clockwise or counterclockwise. Implement this functionality. The Adjust menu could
also contain menu items that invoke the existing Larger and Smaller functionality, for instance.
Exercise 11.61 The application always resizes its frame in order to ensure that the full image
is always visible. Having a large frame is not always desirable. Read the documentation on the
JScrollPane class. Instead of adding the ImagePanel directly to the content pane, place
the panel in a JScrollPane and add the scroll pane to the content pane. Display a large im-
age and experiment with resizing the window. What difference does having a scroll pane make?
Does this allow you to display images that would otherwise be too large for the screen?
Exercise 11.62 Change your application so that it can open multiple images at the same
time (but only one image is displayed at any time). Then add a pop-up menu (using class
JComboBox ) to select the image to display.
Exercise 11.63 As an alternative to using a JComboBox as in Exercise 11.62, use a
tabbed pane (class JTabbedPane ) to hold multiple open images.