xdev.util

Interface ProgressMonitor

public interface ProgressMonitor

The ProgressMonitor interface is implemented by objects that monitor the progress of an activity; the methods in this interface are invoked by code that performs the activity.

All activity is broken down into a linear sequence of tasks against which progress is reported. When a task begins, a beginTask(String, int) notification is reported, followed by any number and mixture of progress reports (worked(int)). When the task is eventually completed, a done() notification is reported.

A request to cancel an operation can be signaled using the cancel() method. Operations taking a progress monitor are expected to poll the monitor (using isCanceled()) periodically and abort at their earliest convenience. Operation can however choose to ignore cancelation requests.

Since notification is synchronous with the activity itself, the listener should provide a fast and robust implementation. If the handling of notifications would involve blocking operations, or operations which might throw uncaught exceptions, the notifications should be queued, and the actual processing deferred (or perhaps delegated to a separate thread).

Since:

3.0

Field Summary

Fields

Modifier and Type	Field and Description
static ProgressMonitor	DUMMY A default no-op implementation of ProgressMonitor.
static int	UNKNOWN Constant indicating an unknown amount of work.

Method Summary

Modifier and Type	Method and Description
void	beginTask(String name, int totalWork) Notifies that a task is beginning.
void	cancel() Indicates that cancelation has been requested (but not necessarily acknowledged).
void	done() Notifies that the work is done; that is, either the task is completed or the user canceled it.
boolean	isCanceled() Returns whether cancelation of current operation has been requested.
void	setTaskName(String name) Sets the task name to the given value.
void	worked(int progress) Notifies that a given number of work unit of the task has been completed.

Field Detail

DUMMY

static final ProgressMonitor DUMMY

A default no-op implementation of ProgressMonitor.

UNKNOWN

static final int UNKNOWN

Constant indicating an unknown amount of work.

See Also:

Constant Field Values

Method Detail

beginTask

void beginTask(String name,
               int totalWork)

Notifies that a task is beginning.

Parameters:

name - the name (or description) of the main task

totalWork - the total number of work units into which the main task is been subdivided. If the value is UNKNOWN the implementation is free to indicate progress in a way which doesn't require the total number of work units in advance.

worked

void worked(int progress)

Notifies that a given number of work unit of the task has been completed. Note that this amount represents an installment, as opposed to a cumulative amount of work done to date.

Parameters:

progress - the number of work units just completed

setTaskName

void setTaskName(String name)

Sets the task name to the given value. This method is used to restore the task label after a nested operation was executed.

Parameters:

name - the name (or description) of the main task

See Also:

beginTask(java.lang.String, int)

done

void done()

Notifies that the work is done; that is, either the task is completed or the user canceled it.

isCanceled

boolean isCanceled()

Returns whether cancelation of current operation has been requested. Long-running operations should poll to see if cancelation has been requested.

Returns:

true if cancellation has been requested, and false otherwise

See Also:

cancel()

cancel

void cancel()

Indicates that cancelation has been requested (but not necessarily acknowledged).

See Also:

isCanceled()