- java.lang.Object
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- java.util.Observable
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@Deprecated(since="9") public class Observable extends Object
Deprecated.This class and theObserverinterface have been deprecated. The event model supported byObserverandObservableis quite limited, the order of notifications delivered byObservableis unspecified, and state changes are not in one-for-one correspondence with notifications. For a richer event model, consider using thejava.beanspackage. For reliable and ordered messaging among threads, consider using one of the concurrent data structures in thejava.util.concurrentpackage. For reactive streams style programming, see theFlowAPI.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 theObservable'snotifyObserversmethod causes all of its observers to be notified of the change by a call to theirupdatemethod.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
waitandnotifymechanism of classObject.When an observable object is newly created, its set of observers is empty. Two observers are considered the same if and only if the
equalsmethod returns true for them.
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Constructor Summary
Constructors Constructor Description Observable()Deprecated.Construct an Observable with zero Observers.
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Method Summary
All Methods Instance Methods Concrete Methods Deprecated Methods Modifier and Type Method Description voidaddObserver(Observer o)Deprecated.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.protected voidclearChanged()Deprecated.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 thehasChangedmethod will now returnfalse.intcountObservers()Deprecated.Returns the number of observers of thisObservableobject.voiddeleteObserver(Observer o)Deprecated.Deletes an observer from the set of observers of this object.voiddeleteObservers()Deprecated.Clears the observer list so that this object no longer has any observers.booleanhasChanged()Deprecated.Tests if this object has changed.voidnotifyObservers()Deprecated.If this object has changed, as indicated by thehasChangedmethod, then notify all of its observers and then call theclearChangedmethod to indicate that this object has no longer changed.voidnotifyObservers(Object arg)Deprecated.If this object has changed, as indicated by thehasChangedmethod, then notify all of its observers and then call theclearChangedmethod to indicate that this object has no longer changed.protected voidsetChanged()Deprecated.Marks thisObservableobject as having been changed; thehasChangedmethod will now returntrue.
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Method Detail
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addObserver
public void addObserver(Observer o)
Deprecated.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. The order in which notifications will be delivered to multiple observers is not specified. See the class comment.- Parameters:
o- an observer to be added.- Throws:
NullPointerException- if the parameter o is null.
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deleteObserver
public void deleteObserver(Observer o)
Deprecated.Deletes an observer from the set of observers of this object. Passingnullto this method will have no effect.- Parameters:
o- the observer to be deleted.
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notifyObservers
public void notifyObservers()
Deprecated.If this object has changed, as indicated by thehasChangedmethod, then notify all of its observers and then call theclearChangedmethod to indicate that this object has no longer changed.Each observer has its
updatemethod called with two arguments: this observable object andnull. In other words, this method is equivalent to:notifyObservers(null)
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notifyObservers
public void notifyObservers(Object arg)
Deprecated.If this object has changed, as indicated by thehasChangedmethod, then notify all of its observers and then call theclearChangedmethod to indicate that this object has no longer changed.Each observer has its
updatemethod called with two arguments: this observable object and theargargument.- Parameters:
arg- any object.- See Also:
clearChanged(),hasChanged(),Observer.update(java.util.Observable, java.lang.Object)
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deleteObservers
public void deleteObservers()
Deprecated.Clears the observer list so that this object no longer has any observers.
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setChanged
protected void setChanged()
Deprecated.Marks thisObservableobject as having been changed; thehasChangedmethod will now returntrue.
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clearChanged
protected void clearChanged()
Deprecated.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 thehasChangedmethod will now returnfalse. This method is called automatically by thenotifyObserversmethods.
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hasChanged
public boolean hasChanged()
Deprecated.Tests if this object has changed.- Returns:
trueif and only if thesetChangedmethod has been called more recently than theclearChangedmethod on this object;falseotherwise.- See Also:
clearChanged(),setChanged()
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countObservers
public int countObservers()
Deprecated.Returns the number of observers of thisObservableobject.- Returns:
- the number of observers of this object.
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