jebl.util
Class ProgressListener

java.lang.Object
  jebl.util.ProgressListener

All Implemented Interfaces:

Cancelable

Direct Known Subclasses:

BasicProgressListener, CompositeProgressListener, ProgressListener.Wrapper

public abstract class ProgressListener
extends java.lang.Object
implements Cancelable

Version:

$Id: ProgressListener.java 1068 2010-09-08 23:59:59Z matt_kearse $ ProgressListener guarantees the following contract: A call to any of the methods setProgress(), setMessage(), isCanceled() and setIndeterminateProgress() at a given time yields the same result as a call to another of these methods would have resulted at the same time. Once the task whose progress we are observing has been canceled, calls to either of these methods reflect this. This does not prevent subclasses from introducing a way to "reset" a ProgressListener that was previously canceled from not being canceled any more. Any object may exhibit undefined behaviour when dealing with a ProgressListener that is not fulfilling this contract.

Author:

Matt Kearse

Nested Class Summary

static class

ProgressListener.Wrapper A decorator progress listener which delegates all method calls to an internal progress listener.

Field Summary

static ProgressListener

EMPTY A ProgressListener that ignores all events and always returns false from isCanceled().

Constructor Summary

ProgressListener()

Method Summary

void	addFeedbackAction(java.lang.String label, SimpleListener listener) Equivalent to addFeedbackAction(label,"",listener)
void	addFeedbackAction(java.lang.String label, java.lang.String description, SimpleListener listener) Adds an action that can choose to provide feedback.
abstract boolean	isCanceled() This method must be implemented by all subclasses.
void	removeFeedbackAction(java.lang.String label) Removes a feedback action previously added using addFeedbackAction(String, jebl.util.SimpleListener).
boolean	setImage(java.awt.Image image) Set an image associated with the current progress.
boolean	setIndeterminateProgress() Sets indefinite progress (i.e.
boolean	setMessage(java.lang.String message) Set visible user message.
boolean	setProgress(double fractionCompleted)
boolean	setProgress(int currentStep, int numberOfSteps) Same as calling setProgress(((double)currentStep)/numberOfSteps)
boolean	setProgress(long currentStep, long numberOfSteps) Same as calling setProgress(((double)currentStep)/numberOfSteps)
void	setTitle(java.lang.String title) Sets a title associated with whatever is being done.

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY

public static final ProgressListener EMPTY

A ProgressListener that ignores all events and always returns false from isCanceled(). Useful when you don't care about the progress results or canceling the operation.

Constructor Detail

ProgressListener

public ProgressListener()

Method Detail

setProgress

public final boolean setProgress(double fractionCompleted)

Parameters:

fractionCompleted - a number between 0 and 1 inclusive representing the fraction of the operation completed. If you are unsure of the fraction completed, call setIndeterminateProgress() instead.

Returns:

true if the user has requested that this operation be canceled.

setProgress

public final boolean setProgress(int currentStep,
                                 int numberOfSteps)

Same as calling setProgress(((double)currentStep)/numberOfSteps)

Parameters:

currentStep - between 0 and numberOfSteps inclusive

numberOfSteps - the total number of steps. Must be greater than 0.

Returns:

true if the user has requested that this operation be canceled.

setProgress

public final boolean setProgress(long currentStep,
                                 long numberOfSteps)

Same as calling setProgress(((double)currentStep)/numberOfSteps)

Parameters:

currentStep - between 0 and numberOfSteps inclusive

numberOfSteps - the total number of steps. Must be greater than 0.

Returns:

true if the user has requested that this operation be canceled.

setIndeterminateProgress

public final boolean setIndeterminateProgress()

Sets indefinite progress (i.e. "some progress has happened, but I don't know how close we are to finishing").

Returns:

true if the user has requested that this operation be canceled.

setMessage

public final boolean setMessage(java.lang.String message)

Set visible user message.

Parameters:

message - a user visible message. If this is null, it will be automatically replaced with an empty string.

Returns:

true if the user has requested that this operation be canceled.

setImage

public final boolean setImage(java.awt.Image image)

Set an image associated with the current progress. A progress listener may choose to optionally display this image wherever is appropriate.

Parameters:

image - an image

Returns:

true if the user has requested that this operation be canceled.

addFeedbackAction

public void addFeedbackAction(java.lang.String label,
                              SimpleListener listener)

Equivalent to addFeedbackAction(label,"",listener)

addFeedbackAction

public void addFeedbackAction(java.lang.String label,
                              java.lang.String description,
                              SimpleListener listener)

Adds an action that can choose to provide feedback. For example, an operation may choose to provide a "Skip to next step" button alongside the cancel button. There is no requirement that a ProgressListener actually present this to the user - it may choose to ignore this method, in which case listener will never be fired.

Parameters:

label - a label describing this feedback action. For example, "Skip to next step"

listener - a listener to be notified when the user chooses to invoke this action

removeFeedbackAction

public void removeFeedbackAction(java.lang.String label)

Removes a feedback action previously added using addFeedbackAction(String, jebl.util.SimpleListener).

Parameters:

label - The label used as a parameter to addFeedbackAction(String, jebl.util.SimpleListener)

setTitle

public void setTitle(java.lang.String title)

Sets a title associated with whatever is being done. This will not necessarily even be presented to the user, but typically will be presented as the title of a progress window.

Parameters:

title - the title of a progress window (if any). Must not be null.

isCanceled

public abstract boolean isCanceled()

This method must be implemented by all subclasses. It is called from setProgress(double), setIndeterminateProgress() and setMessage(java.lang.String) to determine the return value of these methods.

Specified by:

isCanceled in interface Cancelable

Returns:

true if the user has requested that this operation be canceled.