oracle.ifs.utils.action

Class ActionQueue

java.lang.Object

oracle.ifs.utils.action.ActionQueue

All Implemented Interfaces:

Runnable

public class ActionQueue
extends Object
implements Runnable

The ActionQueue class allows clients to queue a list of Action instances for execution in a background thread. ActionQueue supports a listener-style interface for observing such events as an Action having started or the ActionQueue having failed.

Version:

1.6

Author:

Luis Saenz

Modified:

lsaenz 08/02/2000 Changed to invoke the Action.failed method., lsaenz 04/02/2000 Updated comments; changed method names., lsaenz 02/16/2000 Changed name of class to ActionQueue; removed ability to undo (never used)., lsaenz 02/11/2000 Fixed some concurrency issues; now uses EventListenerList., lsaenz 02/09/2000 Added method getActions., lsaenz 02/06/2000 Decoupled Action from Settings, added actionStarting and actionFinished events., lsaenz 12/21/1999 Now makes use of Observer pattern to notify registered objects that the configuration process has finished or failed because of an error., lsaenz 12/10/1999 Catches Throwable instead of just Exception so that Errors are caught., lsaenz 11/15/1999 Created.

Constructor Summary

Constructors

Constructor and Description
ActionQueue() Creates a new ActionQueue.

Method Summary

Modifier and Type	Method and Description
void	addAction(Action action) Adds an Action to the end of this ActionQueue.
void	addActionQueueListener(ActionQueueListener listener) Adds an ActionQueueListener to the list of objects that are interested in observing events from this ActionQueue.
protected void	fireActionFinished(Action action) Reports that an Action has completed successfully.
protected void	fireActionQueueFailed(Throwable error) Reports that the ActionQueue failed.
protected void	fireActionQueueFinished() Reports that the ActionQueue has finished successfully.
protected void	fireActionStarting(Action action) Reports that an Action is about to be performed.
int	getActionCount() Returns the number of Actions in this ActionQueue.
Enumeration	getActions() Returns the Actions in this ActionQueue.
void	insertActionAt(Action action, int index) Inserts an Action into this ActionQueue at a specified index.
boolean	isRunning() Returns true if this ActionQueue is currently executing.
void	removeActionAt(int index) Removes an Action occuring at a specified index from this ActionQueue.
void	removeActionQueueListener(ActionQueueListener listener) Removes an ActionQueueListener such that it no longer receives ActionQueue event notifications.
void	run() Executes this ActionQueue.
void	start() Performs all the Actions in this ActionQueue.
void	stop() Attempts to stop this ActionQueue.
void	waitUntilDone() Blocks the invoking Thread until the ActionQueue has completed.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ActionQueue

public ActionQueue()

Creates a new ActionQueue.

Method Detail

addAction

public void addAction(Action action)

Adds an Action to the end of this ActionQueue.

Parameters:

action - the Action to add.

getActions

public Enumeration getActions()

Returns the Actions in this ActionQueue.

Returns:

an Enumeration of Actions in this ActionQueue.

addActionQueueListener

public void addActionQueueListener(ActionQueueListener listener)

Adds an ActionQueueListener to the list of objects that are interested in observing events from this ActionQueue.

Parameters:

listener - the ActionQueueListener to add.

removeActionQueueListener

public void removeActionQueueListener(ActionQueueListener listener)

Removes an ActionQueueListener such that it no longer receives ActionQueue event notifications.

Parameters:

listener - the ActionQueueListener to remove.

insertActionAt

public void insertActionAt(Action action,
                           int index)

Inserts an Action into this ActionQueue at a specified index.

Parameters:

action - the Action to add.

index - the index that specifies the order when the action should occur.

Throws:

ArrayIndexOutOfBoundsException - if the index is invalid.

removeActionAt

public void removeActionAt(int index)

Removes an Action occuring at a specified index from this ActionQueue.

Parameters:

index - the index that specifies the Action to be removed.

Throws:

ArrayIndexOutOfBoundsException - if the index is invalid.

getActionCount

public int getActionCount()

Returns the number of Actions in this ActionQueue.

start

public void start()

Performs all the Actions in this ActionQueue.
(The ActionQueue will invoke the perform method on every Action that has been added to its queue.)

Note: This method starts a separate Thread. It can be invoked only when the ActionQueue is idle. That is, while actions are being performed (the background Thread is still alive), this method will do nothing.

stop

public void stop()

Attempts to stop this ActionQueue. If this ActionQueue is idle, this method will do nothing. Otherwise, it will invoke the stop method on the currently executing Action. Once this Action has stopped, no other Action will be performed and the ActionQueue will stop.

Invoking this method should stop this ActionQueue in a reasonable amount of time, as long as the currently executing Action implements the stop method correctly, according to the contract defined by the Action interface. Clients can use the isRunning to find out if the ActionQueue has stopped.

Note: Once this method has been invoked, the ActionQueue will no longer report that it has completed or failed. The ActionQueue will also no longer report that the currently executing Action has finished. It is up to the client to wait for the ActionQueue to finish because there can be no guarantee that the currently executing Action will stop. Clients can use the waitUntilDone method immediately after invoking this method to block until the ActionQueue has stopped.

isRunning

public boolean isRunning()

Returns true if this ActionQueue is currently executing. A return value of true implies that this ActionQueue's background thread is still alive.

Returns:

true if this ActionQueue is currently running.

waitUntilDone

public void waitUntilDone()
                   throws InterruptedException

Blocks the invoking Thread until the ActionQueue has completed. This could be when the ActionQueue has finished successfully, failed, or has been stopped.

Throws:

InterruptedException - if the Thread is interrupted.

run

public void run()

Executes this ActionQueue. Invokes the perform method for every Action. Also notifies registered listeners of Action events.

Specified by:

run in interface Runnable

fireActionQueueFinished

protected void fireActionQueueFinished()

Reports that the ActionQueue has finished successfully.

fireActionQueueFailed

protected void fireActionQueueFailed(Throwable error)

Reports that the ActionQueue failed.

Parameters:

error - the Exception or Error that caused the failure.

fireActionStarting

protected void fireActionStarting(Action action)

Reports that an Action is about to be performed.

Parameters:

action - the Action that is about to begin.

fireActionFinished

protected void fireActionFinished(Action action)

Reports that an Action has completed successfully.

Parameters:

action - the Action that has finished.