Java 6 Illuminated: An Active Learning Approach, 2nd Edition

848 CHAPTER 12 Graphical User Interfaces

Figure 12.7

Running Example 12.4

In the constructor, at lines 40–41, we declare and instantiate the Button-

Handler event handler, bh. At lines 43–45, we call the addActionListener

method to register the handler on our two buttons.

The output of this example is shown in Figure 12.7. When you run this

example, try entering a valid number into the text field, and press each but-

ton. Then try to enter text that cannot be converted to a number. Also, try

deleting either statement that registers the event listener on the buttons

(line 44 or 45), and run the application again.

12.7 Radio Buttons and Checkboxes

If you ...