The {@code AccessibilityListenerList} is a copy of the Swing + * {@link javax.swing.event.EventListenerList EventListerList} class. + * + */ + +@jdk.Exported +public class AccessibilityListenerList { + /* A null array to be shared by all empty listener lists */ + private final static Object[] NULL_ARRAY = new Object[0]; + + /** + * The list of listener type, listener pairs + */ + protected transient Object[] listenerList = NULL_ARRAY; + + /** + * Passes back the event listener list as an array of listener type, listener pairs. + * Note that for performance reasons, this implementation passes back the actual + * data structure in which the listener data is stored internally. This method + * is guaranteed to pass back a non-null array, so that no null-checking + * is required in fire methods. A zero-length array of Object is returned if + * there are currently no listeners. + *
+ * Absolutely no modification of the data contained in this array should be + * made. If any such manipulation is necessary, it should be done on a copy + * of the array returned rather than the array itself. + * + * @return an array of listener type, listener pairs. + */ + public Object[] getListenerList() { + return listenerList; + } + + /** + * Returns the total number of listeners for this listener list. + * + * @return the total number of listeners for this listener list. + */ + public int getListenerCount() { + return listenerList.length/2; + } + + /** + * Return the total number of listeners of the supplied type + * for this listener list. + * + * @param t the type of the listener to be counted + * @return the number of listeners found + */ + public int getListenerCount(Class t) { + int count = 0; + Object[] lList = listenerList; + for (int i = 0; i < lList.length; i+=2) { + if (t == (Class)lList[i]) + count++; + } + return count; + } + + /** + * Add the listener as a listener of the specified type. + * + * @param t the type of the listener to be added + * @param l the listener to be added + */ + public synchronized void add(Class t, EventListener l) { + if (!t.isInstance(l)) { + throw new IllegalArgumentException("Listener " + l + + " is not of type " + t); + } + if (l ==null) { + throw new IllegalArgumentException("Listener " + l + + " is null"); + } + if (listenerList == NULL_ARRAY) { + // if this is the first listener added, + // initialize the lists + listenerList = new Object[] { t, l }; + } else { + // Otherwise copy the array and add the new listener + int i = listenerList.length; + Object[] tmp = new Object[i+2]; + System.arraycopy(listenerList, 0, tmp, 0, i); + + tmp[i] = t; + tmp[i+1] = l; + + listenerList = tmp; + } + } + + /** + * Remove the listener as a listener of the specified type. + * + * @param t the type of the listener to be removed + * @param l the listener to be removed + */ + public synchronized void remove(Class t, EventListener l) { + if (!t.isInstance(l)) { + throw new IllegalArgumentException("Listener " + l + + " is not of type " + t); + } + if (l ==null) { + throw new IllegalArgumentException("Listener " + l + + " is null"); + } + + // Is l on the list? + int index = -1; + for (int i = listenerList.length-2; i>=0; i-=2) { + if ((listenerList[i]==t) && (listenerList[i+1] == l)) { + index = i; + break; + } + } + + // If so, remove it + if (index != -1) { + Object[] tmp = new Object[listenerList.length-2]; + // Copy the list up to index + System.arraycopy(listenerList, 0, tmp, 0, index); + // Copy from two past the index, up to + // the end of tmp (which is two elements + // shorter than the old list) + if (index < tmp.length) + System.arraycopy(listenerList, index+2, tmp, index, + tmp.length - index); + // set the listener array to the new array or null + listenerList = (tmp.length == 0) ? NULL_ARRAY : tmp; + } + } + + /** + * Return a string representation of the {@code AccessibilityListenerList}. + * + * @return a string representation of the {@code AccessibilityListenerList}. + */ + public String toString() { + Object[] lList = listenerList; + String s = "EventListenerList: "; + s += lList.length/2 + " listeners: "; + for (int i = 0 ; i <= lList.length-2 ; i+=2) { + s += " type " + ((Class)lList[i]).getName(); + s += " listener " + lList[i+1]; + } + return s; + } +}