Java Reference
In-Depth Information
// Add the menu item listeners
moveItem.addActionListener(this);
deleteItem.addActionListener(this);
rotateItem.addActionListener(this);
sendToBackItem.addActionListener(this);
}
We add the menu items using the
add()
method that accepts a
String
argument, and returns a
reference to the
JMenuItem
object that it creates. We then use these references to add the view object
as the listener for all the menu items in the pop-up.
We must make sure the
SketchView
class declares that it implements the
ActionListener
interface:
class SketchView extends JComponent
implements Observer, Constants, ActionListener {
We can add the
actionPerformed()
method to
SketchView
that will handle action events from
the menu items.
As with the new data members above, be careful to add this to the
SketchView
class
and not inside the inner
MouseHandler
class by mistake!
public void actionPerformed(ActionEvent e ) {
Object source = e.getSource();
if(source == moveItem) {
// Process a move...
} else if(source == deleteItem) {
// Process a delete...
} else if(source == rotateItem) {
// Process a rotate
} else if(source == sendToBackItem) {
// Process a send-to-back...
}
}
Of course, we will need two more import statements in the
SketchView.java
file:
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
To pop the menu we need to modify the code in the
mouseReleased()
method of the
MouseHandler
inner class a little:
