By calling setEnabled(false), you can disable a button and give it a muted appearance and...

By calling

setEnabled(false),

you can disable a button and give it a muted appearance and make its listener unresponsive to clicks on it. Modify Figure’s program so that the factorial button is initially disabled. Enable it only after the user enters a character in the

xBox

text box. To enable it, create a key listener for the

xBox

text box, and have the key listener’s

keyTyped

event handler call

setEnabled(true).

Use the following key listener code skeleton:

private class KeyListener extends KeyAdapter{      public void keyTyped(KeyEvent e)     {          …     }} // end class KeyListene

Note

extends KeyAdapter

in the above class heading. An adapter class implements an interface by providing an empty-bodied method for each method in the interface. In this case, the

KeyAdapter

API class implements the

KeyListener

API interface.

Figure Modified Listener class for the FactorialButton program