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// This example is from the book _Java AWT Reference_ by John Zukowski.
// Written by John Zukowski. Copyright (c) 1997 O'Reilly & Associates.
// You may study, use, modify, and distribute this example for any purpose.
// This example is provided WITHOUT WARRANTY either expressed or
import java.awt.AWTEvent;
import java.awt.AWTEventMulticaster;
import java.awt.Component;
import java.awt.Frame;
import java.awt.ItemSelectable;
import java.awt.SystemColor;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.event.MouseEvent;
class ItemEventComponent extends Component implements ItemSelectable {
boolean selected;
int i = 0;
ItemListener itemListener = null;
ItemEventComponent() {
enableEvents(AWTEvent.MOUSE_EVENT_MASK);
}
public Object[] getSelectedObjects() {
Object o[] = new Object[1];
o[0] = new Integer(i);
return o;
}
public void addItemListener(ItemListener l) {
itemListener = AWTEventMulticaster.add(itemListener, l);
}
public void removeItemListener(ItemListener l) {
itemListener = AWTEventMulticaster.remove(itemListener, l);
}
public void processEvent(AWTEvent e) {
if (e.getID() == MouseEvent.MOUSE_PRESSED) {
if (itemListener != null) {
selected = !selected;
i++;
itemListener.itemStateChanged(new ItemEvent(this, ItemEvent.ITEM_STATE_CHANGED,
getSelectedObjects(), (selected ? ItemEvent.SELECTED : ItemEvent.DESELECTED)));
}
}
}
}
public class MainClass extends Frame implements ItemListener {
MainClass() {
super("Listening In");
ItemEventComponent c = new ItemEventComponent();
add(c, "Center");
c.addItemListener(this);
c.setBackground(SystemColor.control);
setSize(200, 200);
}
public void itemStateChanged(ItemEvent e) {
Object[] o = e.getItemSelectable().getSelectedObjects();
Integer i = (Integer) o[0];
System.out.println(i);
}
public static void main(String args[]) {
MainClass f = new MainClass();
f.show();
}
}
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