com.jgoodies.binding.extras
Class DelayedWriteValueModel

java.lang.Object
  extended by AbstractBean
      extended by com.jgoodies.binding.beans.Model
          extended by com.jgoodies.binding.value.AbstractValueModel
              extended by com.jgoodies.binding.extras.DelayedWriteValueModel
All Implemented Interfaces:
Observable, ValueModel

public final class DelayedWriteValueModel
extends AbstractValueModel

A ValueModel that deferres write-access for a specified delay. Useful to coalesce frequent changes. For example if a heavy computation shall be performed only for a "stable" selection after a series of quick selection changes.

Wraps a given subject ValueModel and returns the subject value or the value to be set as this model's value. Observes subject value changes and forwards them to listeners of this model. If a value is set to this model, a Swing Timer is used to delay the value commit to the subject. A previously started timer - if any - will be stopped before.

TODO: Describe how and when listeners get notified about the delayed change.

TODO: Write about the recommended delay time - above the double-click time and somewhere below a second, e.g. 100ms to 200ms.

TODO: Write about a slightly different commit handling. The current implementation defers the commit until the value is stable for the specified delay; it's a DelayUntilStableForXXXmsValueModel. Another feature is to delay for a specified time but ensure that some commits and change notifications happen. The latter is a CoalescingWriteValueModel.

TODO: Summarize the differences between the DelayedReadValueModel, this DelayedWriteValueModel, and the DelayedPropertyChangeHandler.

Version:
$Revision: 1.16 $
Author:
Karsten Lentzsch
See Also:
DelayedReadValueModel, DelayedPropertyChangeHandler, Timer

Field Summary
 
Fields inherited from class com.jgoodies.binding.value.AbstractValueModel
PROPERTYNAME_VALUE
 
Constructor Summary
DelayedWriteValueModel(ValueModel subject, int delay)
          Constructs a DelayedWriteValueModel for the given subject ValueModel and the specified Timer delay in milliseconds with coalescing disabled.
DelayedWriteValueModel(ValueModel subject, int delay, boolean coalesce)
          Constructs a DelayedWriteValueModel for the given subject ValueModel and the specified Timer delay in milliseconds with coalescing disabled.
 
Method Summary
 int getDelay()
          Returns the delay, in milliseconds, that is used to defer value commits.
 java.lang.Object getValue()
          Returns the subject's value or in case of a pending commit, the pending new value.
 boolean isCoalesce()
          Returns if this model coalesces all pending changes or not.
 boolean isPending()
          Checks and answers whether this model has one or more pending changes.
 void setCoalesce(boolean b)
          Sets if this model shall coalesce all pending changes or not.
 void setDelay(int delay)
          Sets the delay, in milliseconds, that is used to defer value commits.
 void setValue(java.lang.Object newValue)
          Sets the given new value after this model's delay.
 void stop()
          Stops a running timer.
 
Methods inherited from class com.jgoodies.binding.value.AbstractValueModel
addValueChangeListener, booleanValue, doubleValue, fireValueChange, fireValueChange, fireValueChange, fireValueChange, fireValueChange, fireValueChange, fireValueChange, floatValue, getString, intValue, longValue, paramString, removeValueChangeListener, setValue, setValue, setValue, setValue, setValue, toString, valueString
 
Methods inherited from class com.jgoodies.binding.beans.Model
createPropertyChangeSupport, firePropertyChange
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface com.jgoodies.binding.beans.Observable
addPropertyChangeListener, removePropertyChangeListener
 

Constructor Detail

DelayedWriteValueModel

public DelayedWriteValueModel(ValueModel subject,
                              int delay)
Constructs a DelayedWriteValueModel for the given subject ValueModel and the specified Timer delay in milliseconds with coalescing disabled.

Parameters:
subject - the underlying (or wrapped) ValueModel
delay - the milliseconds to wait before a change shall be committed
Throws:
java.lang.IllegalArgumentException - if the delay is negative

DelayedWriteValueModel

public DelayedWriteValueModel(ValueModel subject,
                              int delay,
                              boolean coalesce)
Constructs a DelayedWriteValueModel for the given subject ValueModel and the specified Timer delay in milliseconds with coalescing disabled.

Parameters:
subject - the underlying (or wrapped) ValueModel
delay - the milliseconds to wait before a change shall be committed
coalesce - true to coalesce all pending changes, false to fire changes with the delay when an update has been received
Throws:
java.lang.IllegalArgumentException - if the delay is negative
See Also:
setCoalesce(boolean)
Method Detail

getValue

public java.lang.Object getValue()
Returns the subject's value or in case of a pending commit, the pending new value.

Returns:
the subject's current or future value.

setValue

public void setValue(java.lang.Object newValue)
Sets the given new value after this model's delay. Does nothing if the new value and the latest pending value are the same. TODO: Describe how and when listeners get notified about the delayed value change.

Parameters:
newValue - the value to set

getDelay

public int getDelay()
Returns the delay, in milliseconds, that is used to defer value commits.

Returns:
the delay, in milliseconds, that is used to defer value commits
See Also:
setDelay(int)

setDelay

public void setDelay(int delay)
Sets the delay, in milliseconds, that is used to defer value commits.

Parameters:
delay - the delay, in milliseconds, that is used to defer value commits
See Also:
getDelay()

isCoalesce

public boolean isCoalesce()
Returns if this model coalesces all pending changes or not.

Returns:
true if all pending changes will be coalesced, false if pending changes are fired with a delay when an update has been received.
See Also:
setCoalesce(boolean)

setCoalesce

public void setCoalesce(boolean b)
Sets if this model shall coalesce all pending changes or not. In this case, a change event will be fired first, if no updates have been received for this model's delay. If coalesce is false, a change event will be fired with this model's delay when an update has been received.

The default value is false.

Note that this value is not the #coalesce value of this model's internal Swing timer.

Parameters:
b - true to coalesce, false to fire separate changes

stop

public void stop()
Stops a running timer. Pending changes - if any - are canceled and won't be performed by the ValueUpdateListener.

Since:
1.2

isPending

public boolean isPending()
Checks and answers whether this model has one or more pending changes.

Returns:
true if there are pending changes, false if not.
Since:
2.0.4


Copyright © 2002-2010 JGoodies Karsten Lentzsch. All Rights Reserved.