frysk.rt
Class UpdatingDisplayValue

java.lang.Object
  frysk.rt.UpdatingDisplayValue

public class UpdatingDisplayValue
extends Object

An UpdatingDisplayValue is nearly identical to a DisplayValue, except that an UpdatingDisplayValue is provided with additional information that enables it to automatically refresh itself whenever the task given to it changes state. Objects can be notified of updates by using the addObserver method.

Method Summary

void	addObserver(DisplayValueObserver obs) Adds an observer to listen for changes to this DisplayValue
void	disable() Disables the display, stopping all notification of changes to the underlying expression.
void	enable() Re-enables the display, resuming notification of events to all observers
boolean	equals(Object other)
FrameIdentifier	getFrameIdentifier()
int	getId()
String	getName()
Task	getTask()
Value	getValue()
boolean	isAvailable()
boolean	isEnabled() Check if this display is enabled or not.
void	refresh() Updates the display to refect the new variable value
boolean	removeObserver(DisplayValueObserver obs) Removes the given observer from the list of observers

Methods inherited from class java.lang.Object

getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

refresh

public void refresh()

Updates the display to refect the new variable value

addObserver

public void addObserver(DisplayValueObserver obs)

Adds an observer to listen for changes to this DisplayValue

Parameters:

obs - The new observer to be notified

removeObserver

public boolean removeObserver(DisplayValueObserver obs)

Removes the given observer from the list of observers

Parameters:

obs - The observer to remove

Returns:

True if obs was found and removed, false otherwise

equals

public boolean equals(Object other)

Overrides:

equals in class Object

disable

public void disable()

Disables the display, stopping all notification of changes to the underlying expression.

enable

public void enable()

Re-enables the display, resuming notification of events to all observers

isEnabled

public boolean isEnabled()

Check if this display is enabled or not. A disabled display will not send any notifications regarding changes to the value of the watched expression.

Returns:

True iff this display is enabled, false otherwise

isAvailable

public boolean isAvailable()

Returns:

true iff the variable represented by this Display is in scope

getValue

public Value getValue()

Returns:

The Value object encapsulated by this Display.

getFrameIdentifier

public FrameIdentifier getFrameIdentifier()

getTask

public Task getTask()

getName

public String getName()

getId

public int getId()