Module java.base
Package java.util

Class Observable

java.lang.Object
java.util.Observable

@Deprecated(since="9") public class Observable extends Object
Deprecated.
This class and the Observer interface have been deprecated. The event model supported by Observer and Observable is quite limited, the order of notifications delivered by Observable is unspecified, and state changes are not in one-for-one correspondence with notifications. For a richer event model, consider using the java.beans package. For reliable and ordered messaging among threads, consider using one of the concurrent data structures in the java.util.concurrent package. For reactive streams style programming, see the Flow API.
This class represents an observable object, or "data" in the model-view paradigm. It can be subclassed to represent an object that the application wants to have observed.

An observable object can have one or more observers. An observer may be any object that implements interface Observer. After an observable instance changes, an application calling the Observable's notifyObservers method causes all of its observers to be notified of the change by a call to their update method.

The order in which notifications will be delivered is unspecified. The default implementation provided in the Observable class will notify Observers in the order in which they registered interest, but subclasses may change this order, use no guaranteed order, deliver notifications on separate threads, or may guarantee that their subclass follows this order, as they choose.

Note that this notification mechanism has nothing to do with threads and is completely separate from the wait and notify mechanism of class Object.

When an observable object is newly created, its set of observers is empty. Two observers are considered the same if and only if the equals method returns true for them.

Since:
1.0
See Also: