PPT Slide

Option #1: Event Listeners

As noted, one can ‘addXYZListener’ to a component, e.g.:

class TestApplet extends Applet implements MouseListener{

Button myButton;

public void init(){

myButton = new Button(“Click”);

myButton.addMouseListener(this);

. . .

} // TestApplet

When using listener interfaces, one must code all event methods--even those we are not interested in. Wasted code arises:

public void mouseEntered(MouseEvent e){;}

public void mouseExited(MouseEvent e){;}
public void mouseClicked(MouseEvent e){;}
public void mouseReleased(MouseEvent e){;}

public void mousePressed
(MouseEvent e){
/* handle mouse event */}

“no-op”

methods

Single method we

do something in

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