* Usage example: *
* private volatile Object changeListeners;
*
* public void addMyListener(PropertyChangeListener l)
* {
* synchronized (this) {
* changeListeners = Kit.addListener(changeListeners, l);
* }
* }
*
* public void removeTextListener(PropertyChangeListener l)
* {
* synchronized (this) {
* changeListeners = Kit.removeListener(changeListeners, l);
* }
* }
*
* public void fireChangeEvent(Object oldValue, Object newValue)
* {
* // Get immune local copy
* Object listeners = changeListeners;
* if (listeners != null) {
* PropertyChangeEvent e = new PropertyChangeEvent(
* this, "someProperty" oldValue, newValue);
* for (int i = 0; ; ++i) {
* Object l = Kit.getListener(listeners, i);
* if (l == null)
* break;
* ((PropertyChangeListener)l).propertyChange(e);
* }
* }
* }
*
*
* @param listener Listener to add to bag
* @param bag Current collection of listeners.
* @return A new bag containing all listeners from bag and
* listener.
* @see #removeListener(Object bag, Object listener)
* @see #getListener(Object bag, int index)
*/
public static Object addListener(Object bag, Object listener)
{
if (listener == null) throw new IllegalArgumentException();
if (listener instanceof Object[]) throw new IllegalArgumentException();
if (bag == null) {
bag = listener;
} else if (!(bag instanceof Object[])) {
bag = new Object[] { bag, listener };
} else {
Object[] array = (Object[])bag;
int L = array.length;
// bag has at least 2 elements if it is array
if (L < 2) throw new IllegalArgumentException();
Object[] tmp = new Object[L + 1];
System.arraycopy(array, 0, tmp, 0, L);
tmp[L] = listener;
bag = tmp;
}
return bag;
}
/**
* Remove listener from bag of listeners.
* The function does not modify bag and return a new collection
* containing all listeners from bag except listener.
* If bag does not contain listener, the function returns
* bag.
* * For usage example, see {@link #addListener(Object bag, Object listener)}. * * @param listener Listener to remove from bag * @param bag Current collection of listeners. * @return A new bag containing all listeners from bag except * listener. * @see #addListener(Object bag, Object listener) * @see #getListener(Object bag, int index) */ public static Object removeListener(Object bag, Object listener) { if (listener == null) throw new IllegalArgumentException(); if (listener instanceof Object[]) throw new IllegalArgumentException(); if (bag == listener) { bag = null; } else if (bag instanceof Object[]) { Object[] array = (Object[])bag; int L = array.length; // bag has at least 2 elements if it is array if (L < 2) throw new IllegalArgumentException(); if (L == 2) { if (array[1] == listener) { bag = array[0]; } else if (array[0] == listener) { bag = array[1]; } } else { int i = L; do { --i; if (array[i] == listener) { Object[] tmp = new Object[L - 1]; System.arraycopy(array, 0, tmp, 0, i); System.arraycopy(array, i + 1, tmp, i, L - (i + 1)); bag = tmp; break; } } while (i != 0); } } return bag; } /** * Get listener at index position in bag or null if * index equals to number of listeners in bag. *
* For usage example, see {@link #addListener(Object bag, Object listener)}. * * @param bag Current collection of listeners. * @param index Index of the listener to access. * @return Listener at the given index or null. * @see #addListener(Object bag, Object listener) * @see #removeListener(Object bag, Object listener) */ public static Object getListener(Object bag, int index) { if (index == 0) { if (bag == null) return null; if (!(bag instanceof Object[])) return bag; Object[] array = (Object[])bag; // bag has at least 2 elements if it is array if (array.length < 2) throw new IllegalArgumentException(); return array[0]; } else if (index == 1) { if (!(bag instanceof Object[])) { if (bag == null) throw new IllegalArgumentException(); return null; } Object[] array = (Object[])bag; // the array access will check for index on its own return array[1]; } else { // bag has to array Object[] array = (Object[])bag; int L = array.length; if (L < 2) throw new IllegalArgumentException(); if (index == L) return null; return array[index]; } } static Object initHash(Hashtable h, Object key, Object initialValue) { synchronized (h) { Object current = h.get(key); if (current == null) { h.put(key, initialValue); } else { initialValue = current; } } return initialValue; } private final static class ComplexKey { private Object key1; private Object key2; private int hash; ComplexKey(Object key1, Object key2) { this.key1 = key1; this.key2 = key2; } public boolean equals(Object anotherObj) { if (!(anotherObj instanceof ComplexKey)) return false; ComplexKey another = (ComplexKey)anotherObj; return key1.equals(another.key1) && key2.equals(another.key2); } public int hashCode() { if (hash == 0) { hash = key1.hashCode() ^ key2.hashCode(); } return hash; } } public static Object makeHashKeyFromPair(Object key1, Object key2) { if (key1 == null) throw new IllegalArgumentException(); if (key2 == null) throw new IllegalArgumentException(); return new ComplexKey(key1, key2); } public static String readReader(Reader r) throws IOException { char[] buffer = new char[512]; int cursor = 0; for (;;) { int n = r.read(buffer, cursor, buffer.length - cursor); if (n < 0) { break; } cursor += n; if (cursor == buffer.length) { char[] tmp = new char[buffer.length * 2]; System.arraycopy(buffer, 0, tmp, 0, cursor); buffer = tmp; } } return new String(buffer, 0, cursor); } public static byte[] readStream(InputStream is, int initialBufferCapacity) throws IOException { if (initialBufferCapacity <= 0) { throw new IllegalArgumentException( "Bad initialBufferCapacity: "+initialBufferCapacity); } byte[] buffer = new byte[initialBufferCapacity]; int cursor = 0; for (;;) { int n = is.read(buffer, cursor, buffer.length - cursor); if (n < 0) { break; } cursor += n; if (cursor == buffer.length) { byte[] tmp = new byte[buffer.length * 2]; System.arraycopy(buffer, 0, tmp, 0, cursor); buffer = tmp; } } if (cursor != buffer.length) { byte[] tmp = new byte[cursor]; System.arraycopy(buffer, 0, tmp, 0, cursor); buffer = tmp; } return buffer; } /** * Throws RuntimeException to indicate failed assertion. * The function never returns and its return type is RuntimeException * only to be able to write throw Kit.codeBug() if plain * Kit.codeBug() triggers unreachable code error. */ public static RuntimeException codeBug() throws RuntimeException { RuntimeException ex = new IllegalStateException("FAILED ASSERTION"); // Print stack trace ASAP ex.printStackTrace(System.err); throw ex; } }