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The Java Developers Almanac 1.4Order this book from Amazon. |
e650. Firing Item EventsAn object wishing to fire item events must implementItemSelectable .
This example shows typical code that an object must implement to
fire item events. When an item event is to be fired, fireItemEvent()
should be called.
public class MyComponent implements ItemSelectable { protected EventListenerList listenerList = new EventListenerList(); public Object[] getSelectedObjects() { return selectedObjects; } public void addItemListener(ItemListener l) { listenerList.add(ItemListener.class, l); } public void removeItemListener(ItemListener l) { listenerList.remove(ItemListener.class, l); } // If the item is selected, sel should be true. void fireItemEvent(Object item, boolean sel) { ItemEvent evt = new ItemEvent(this, ItemEvent.ITEM_STATE_CHANGED, item, sel ? ItemEvent.SELECTED : ItemEvent.DESELECTED); // Get list of listeners Object[] listeners = listenerList.getListenerList(); // Send event to all listeners for (int i=0; i<listeners.length-2; i+=2) { if (listeners[i] == ItemListener.class) { ((ItemListener)listeners[i+1]).itemStateChanged(evt); } } } }
e644. Handling Action Events e645. Handling Key Presses e646. Handling Mouse Clicks e647. Handling Mouse Motion e648. Detecting Double and Triple Clicks e649. Handling Focus Changes © 2002 Addison-Wesley. |