gcc/libjava/java/util/Observer.java

/* Observer.java -- an object that will be informed of changes in an Observable
   Copyright (C) 1998, 1999, 2001, 2002 Free Software Foundation, Inc.

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package java.util;

/**
 * Interface that is implemented when a class wants to be informed of changes
 * in Observable objects.
 *
 * @author Warren Levy <warrenl@cygnus.com>
 * @see Observable
 * @status updated to 1.4
 */
public interface Observer
{
  /**
   * This method is called whenever the observable object changes, and has
   * called <code>notifyObservers</code>. The Observable object can pass
   * arbitrary information in the second parameter.
   *
   * @param observable the Observable object that changed
   * @param arg arbitrary information, usually relating to the change
   */
  public void update(Observable observable, Object arg);
}