Reflection, or “A Class Named Class” - Java - page 942

public public void void init () {

JButton b ;
requested = false false ;

Container cp = ( Container ) getContentPane ();
cp . setLayout ( new new FlowLayout ());

String buttonLabel = getParameter ( "buttonlabel" );
iif ( buttonLabel == null

null ) {
buttonLabel = "Draw/Don't Draw" ;

}
cp . add ( b = new

new JButton ( buttonLabel ));
b . addActionListener ( new

new ActionListener () {
/* Button - toggle the state of the "requested" flag, to draw or
* not to draw.
*/
public

public void void actionPerformed ( ActionEvent e ) {

String arg = e . getActionCommand ();
// Invert the state of the draw request.
requested = ! requested ;
do_the_work ();

}

});

}

/** paint() is an AWT Component method, called when the
* component needs to be painted.
*/
public public void void do_the_work () {

/* If the Draw button is selected, draw something */
iif ( requested ) {
showStatus ( "Welcome to Java!" );
} else

else {
showStatus ( "" );

// retract welcome? :-)

}

}

}

If we run it in my AppletViewer , [ 64 ] it shows up as a window with just the Draw button
showing; if you click the button an odd number of times, the screen shows the welcome label
( Figure 23-2 ).