Observable JDK 1.6)

Description

public class Observable

This class represents an observable object, or "data" in the model-view paradigm.

See also: Observable.notifyObservers() Observable.notifyObservers(java.lang.Object) Observer Observer.update(java.util.Observable, java.lang.Object)

Methods

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publicsynchronized void addObserver (Observer o)

Adds an observer to the set of observers for this object, provided that it is not the same as some observer already in the set.

protectedsynchronized void clearChanged ()

Indicates that this object has no longer changed, or that it has already notified all of its observers of its most recent change, so that the hasChanged method will now return false.

Indicates that this object has no longer changed, or that it has
already notified all of its observers of its most recent change,
so that the hasChanged method will now return false.
This method is called automatically by the
notifyObservers methods.
See Also: Observable.notifyObservers(), Observable.notifyObservers(java.lang.Object),

publicsynchronized int countObservers ()

Returns the number of observers of this Observable object.

publicsynchronized void deleteObserver (Observer o)

Deletes an observer from the set of observers of this object.

Deletes an observer from the set of observers of this object.
Passing null to this method will have no effect.
Parameters:
- o - the observer to be deleted.

publicsynchronized void deleteObservers ()

Clears the observer list so that this object no longer has any observers.

publicsynchronized boolean hasChanged ()

Tests if this object has changed.

Tests if this object has changed.
Returns: true if and only if the setChanged method has been called more recently than the clearChanged method on this object; false otherwise.
See Also: Observable.clearChanged(), Observable.setChanged(),

public void notifyObservers ()

If this object has changed, as indicated by the hasChanged method, then notify all of its observers and then call the clearChanged method to indicate that this object has no longer changed.

Each observer has its update method called with two arguments: this observable object and null. In other words, this method is equivalent to:

notifyObservers(null)

See Also: Observable.clearChanged(), Observable.hasChanged(), Observer.update(java.util.Observable, java.lang.Object),

public void notifyObservers (Object arg)

If this object has changed, as indicated by the hasChanged method, then notify all of its observers and then call the clearChanged method to indicate that this object has no longer changed.

Each observer has its update method called with two arguments: this observable object and the arg argument.
Parameters:
- arg - any object.
See Also: Observable.clearChanged(), Observable.hasChanged(), Observer.update(java.util.Observable, java.lang.Object),

protectedsynchronized void setChanged ()

Marks this Observable object as having been changed; the hasChanged method will now return true.