Observable (Codename One API)

java.lang.Object
- java.util.Observable

Direct Known Subclasses:

AsyncResource
```
public class Observable
extends Object
```
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.

See Also:

Observer

Constructor Summary

Constructors
Constructor and Description

Observable()
Constructs a new Observable object.

Constructors
Constructor and Description
`Observable()` Constructs a new `Observable` object.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addObserver(Observer observer)` Adds the specified observer to the list of observers.
`protected void`	`clearChanged()` Clears the changed flag for this `Observable`.
`int`	`countObservers()` Returns the number of observers registered to this `Observable`.
`void`	`deleteObserver(Observer observer)` Removes the specified observer from the list of observers.
`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 void`	`setChanged()` Sets the changed flag for this `Observable`.

Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - Observable
```
public Observable()
```
    Constructs a new Observable object.
- Method Detail
  - addObserver
```
public void addObserver(Observer observer)
```
    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.
  - clearChanged
```
protected void clearChanged()
```
    Clears the changed flag for this Observable. After calling clearChanged(), hasChanged() will return false.
  - countObservers
```
public int countObservers()
```
    Returns the number of observers registered to this Observable.
    
    Returns:
    
    the number of observers.
  - deleteObserver
```
public void deleteObserver(Observer observer)
```
    Removes the specified observer from the list of observers. Passing null won't do anything.
    
    Parameters:
    
    observer - the observer to remove.
  - deleteObservers
```
public void deleteObservers()
```
    Removes all observers from the list of observers.
  - hasChanged
```
public boolean hasChanged()
```
    Returns the changed flag for this Observable.
    
    Returns:
    
    true when the changed flag for this Observable is set, false otherwise.
  - notifyObservers
```
public void notifyObservers()
```
    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).
  - notifyObservers
```
public void notifyObservers(Object data)
```
    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().
  - setChanged
```
protected void setChanged()
```
    Sets the changed flag for this Observable. After calling setChanged(), hasChanged() will return true.

Class Observable

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Observable

Method Detail

addObserver

clearChanged

countObservers

deleteObserver

deleteObservers

hasChanged

notifyObservers

notifyObservers

setChanged