T
- The type of the short-lived objectpublic abstract class ALcdWeakChangeListener<T> extends Object implements ILcdChangeListener
An ILcdChangeListener
implementation which only keeps a WeakReference
to the object it
wants to update when change events are received. This avoids memory leaks, even without removing the
listener.
The class javadoc of ALcdWeakModelListener
contains an example of a weak listener,
and some rules on the usage of weak listeners.
This particular listener has one extra rule compared to the general rules of weak listeners:
ILcdChangeSource
.ILcdChangeSource
Modifier | Constructor and Description |
---|---|
protected |
ALcdWeakChangeListener(T aObjectToModify)
Creates a new
ALcdWeakChangeListener instance which can update aObjectToModify
when it receives events. |
Modifier and Type | Method and Description |
---|---|
void |
stateChanged(TLcdChangeEvent aChangeEvent)
Invoked when the target of the listener has changed its state.
|
protected abstract void |
stateChangedImpl(T aToModify,
TLcdChangeEvent aChangeEvent)
This method is called each time a
TLcdChangeEvent is received by this listener,
and the short-living object to modify passed in the constructor of this listener is not yet GC-ed. |
protected ALcdWeakChangeListener(T aObjectToModify)
Creates a new ALcdWeakChangeListener
instance which can update aObjectToModify
when it receives events.
Warning: this listener can only be registered to a ILcdChangeSource
.
The listener will throw exceptions when it receives TLcdChangeEvent
instances where the source is not
an ILcdChangeSource
instance.
aObjectToModify
- The object you want to modify when a TLcdChangeEvent
is received.
This is a short-lived object, while the listener will be attached to a
long-living ILcdChangeSource
objectpublic final void stateChanged(TLcdChangeEvent aChangeEvent)
This method will check whether the short-living object is still available.
If it is, this method will pass the short-living object and the event to the stateChangedImpl(Object, TLcdChangeEvent)
method.
If the short-living object is already garbage collected, this method will de-register the listener from the source.
stateChanged
in interface ILcdChangeListener
aChangeEvent
- The event describing the change.protected abstract void stateChangedImpl(T aToModify, TLcdChangeEvent aChangeEvent)
This method is called each time a TLcdChangeEvent
is received by this listener,
and the short-living object to modify passed in the constructor of this listener is not yet GC-ed.
aToModify
- The object to modify, as passed in the constructor of this class.aChangeEvent
- The received event