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package java.util;

A class can implement the Observer interface when it wants to be informed of changes in observable objects.
Author: Chris Warth
See Also:
Since: 1.0
Deprecated: This interface has been deprecated. See the Observable class for further information.
/** * A class can implement the {@code Observer} interface when it * wants to be informed of changes in observable objects. * * @author Chris Warth * @see java.util.Observable * @since 1.0 * * @deprecated * This interface has been deprecated. See the {@link Observable} * class for further information. */
@Deprecated(since="9") public interface Observer {
This method is called whenever the observed object is changed. An application calls an Observable object's notifyObservers method to have all the object's observers notified of the change.
Params:
  • o – the observable object.
  • arg – an argument passed to the notifyObservers method.
/** * This method is called whenever the observed object is changed. An * application calls an {@code Observable} object's * {@code notifyObservers} method to have all the object's * observers notified of the change. * * @param o the observable object. * @param arg an argument passed to the {@code notifyObservers} * method. */
void update(Observable o, Object arg); }