Observable - Android SDK

Summary: Ctors | Methods | Protected Methods | Inherited Methods | [Expand All]

Added in API level 1

public class

Observable

extends Object

java.lang.Object
↳	java.util.Observable

Known Direct Subclasses

ContentQueryMap

Class Overview

Observable is used to notify a group of Observer objects when a change occurs. On creation, the set of observers is empty. After a change occurred, the application can call the notifyObservers() method. This will cause the invocation of the update() method of all registered Observers. The order of invocation is not specified. This implementation will call the Observers in the order they registered. Subclasses are completely free in what order they call the update methods.

Summary

Public Constructors
	Observable() Constructs a new `Observable` object.

Public Methods
void	addObserver(Observer observer) Adds the specified observer to the list of observers.
int	countObservers() Returns the number of observers registered to this `Observable`.
synchronized void	deleteObserver(Observer observer) Removes the specified observer from the list of observers.
synchronized void	deleteObservers() Removes all observers from the list of observers.
boolean	hasChanged() Returns the changed flag for this `Observable`.
void	notifyObservers() If `hasChanged()` returns `true`, calls the `update()` method for every observer in the list of observers using null as the argument.
void	notifyObservers(Object data) If `hasChanged()` returns `true`, calls the `update()` method for every Observer in the list of observers using the specified argument.

Protected Methods
void	clearChanged() Clears the changed flag for this `Observable`.
void	setChanged() Sets the changed flag for this `Observable`.

[Expand]

Inherited Methods

From class java.lang.Object

Object	clone() Creates and returns a copy of this `Object`.
boolean	equals(Object o) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of `Class` that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait() Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object.
final void	wait(long millis, int nanos) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.
final void	wait(long millis) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.

Public Constructors

public Observable ()

Added in API level 1

Constructs a new Observable object.

Public Methods

public void addObserver (Observer observer)

Added in API level 1

Adds the specified observer to the list of observers. If it is already registered, it is not added a second time.

Parameters

observer	the Observer to add.

public int countObservers ()

Added in API level 1

Returns the number of observers registered to this Observable.

Returns

the number of observers.

public synchronized void deleteObserver (Observer observer)

Added in API level 1

Removes the specified observer from the list of observers. Passing null won't do anything.

Parameters

observer	the observer to remove.

public synchronized void deleteObservers ()

Added in API level 1

Removes all observers from the list of observers.

public boolean hasChanged ()

Added in API level 1

Returns the changed flag for this Observable.

Returns

true when the changed flag for this Observable is set, false otherwise.

public void notifyObservers ()

Added in API level 1

If hasChanged() returns true, calls the update() method for every observer in the list of observers using null as the argument. Afterwards, calls clearChanged().

Equivalent to calling notifyObservers(null).

public void notifyObservers (Object data)

Added in API level 1

If hasChanged() returns true, calls the update() method for every Observer in the list of observers using the specified argument. Afterwards calls clearChanged().

Parameters

data	the argument passed to `update()`.

Protected Methods

protected void clearChanged ()

Added in API level 1

Clears the changed flag for this Observable. After calling clearChanged(), hasChanged() will return false.

protected void setChanged ()

Added in API level 1

Sets the changed flag for this Observable. After calling setChanged(), hasChanged() will return true.

Results

Interfaces

Classes

Enums

Exceptions

Errors

Observable

Class Overview

See Also

Summary

Public Constructors

public Observable ()

Public Methods

public void addObserver (Observer observer)

Parameters

public int countObservers ()

Returns

public synchronized void deleteObserver (Observer observer)

Parameters

public synchronized void deleteObservers ()

public boolean hasChanged ()

Returns

public void notifyObservers ()

public void notifyObservers (Object data)

Parameters

Protected Methods

protected void clearChanged ()

protected void setChanged ()