Observer

  • The Observer interface allows a class to be informed about changes in observable objects.

  • Implementing the Observer interface requires the class to define the update method, which is called when the observed object changes.

  • The update method receives the changed Observable object and an optional argument passed from the notifyObservers method.
public interface Observer

A class can implement the Observer interface when it wants to be informed of changes in observable objects.

See Also

Public Method Summary

abstract void
update(Observable o, Object arg)
This method is called whenever the observed object is changed.

Public Methods

public abstract void update (Observable o, Object arg)

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.

Parameters
o the observable object.
arg an argument passed to the notifyObservers method.