AWTEventMulticaster: add(ItemListener a, ItemListener b) : AWTEventMulticaster « java.awt « Java by API

1. Java by API
2. java.awt
3. AWTEventMulticaster

AWTEventMulticaster: add(ItemListener a, ItemListener b)

 
// 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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