com.bc.ceres.core

Interface ProgressMonitor

All Known Implementing Classes:

NullProgressMonitor, PrintWriterConciseProgressMonitor, PrintWriterProgressMonitor, ProgressMonitorWrapper, SubProgressMonitor

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()) and subtask notifications (subTask(String)). When the task is eventually completed, a done() notification is reported. After the done() notification, the progress monitor cannot be reused; i.e., beginTask(String, int) cannot be called again after the call to done().

A request to cancel an operation can be signaled using the setCanceled 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).

Clients may implement this interface.

This interface has been more or less directly taken over from the Eclipse Core API.

Field Summary

Fields

Modifier and Type	Field and Description
static ProgressMonitor	NULL
static int	UNKNOWN Constant indicating an unknown amount of work.

Method Summary

Modifier and Type	Method and Description
void	beginTask(String taskName, int totalWork) Notifies that the main task is beginning.
void	done() Notifies that the work is done; that is, either the main task is completed or the user canceled it.
void	internalWorked(double work) Internal method to handle scaling correctly.
boolean	isCanceled() Returns whether cancelation of current operation has been requested.
void	setCanceled(boolean canceled) Sets the cancel state to the given value.
void	setSubTaskName(String subTaskName) Notifies that a subtask of the main task is beginning.
void	setTaskName(String taskName) Sets the task name to the given value.
void	worked(int work) Notifies that a given number of work unit of the main task has been completed.

Field Detail

NULL

static final ProgressMonitor NULL

UNKNOWN

static final int UNKNOWN

Constant indicating an unknown amount of work.

See Also:

Constant Field Values

Method Detail

beginTask

void beginTask(String taskName,
               int totalWork)

Notifies that the main task is beginning. This must only be called once on a given progress monitor instance.

Parameters:

taskName - 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.

done

void done()

Notifies that the work is done; that is, either the main task is completed or the user canceled it. This method may be called more than once (implementations should be prepared to handle this case).

internalWorked

void internalWorked(double work)

Internal method to handle scaling correctly. This method must not be called by a client. Clients should always use the method worked(int).

Parameters:

work - the amount of work done

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:

setCanceled(boolean)

setCanceled

void setCanceled(boolean canceled)

Sets the cancel state to the given value.

Parameters:

canceled - true indicates that cancelation has been requested (but not necessarily acknowledged); false clears this flag

See Also:

isCanceled()

setTaskName

void setTaskName(String taskName)

Sets the task name to the given value. This method is used to restore the task label after a nested operation was executed. Normally there is no need for clients to call this method.

Parameters:

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

See Also:

beginTask(String, int)

setSubTaskName

void setSubTaskName(String subTaskName)

Notifies that a subtask of the main task is beginning. Subtasks are optional; the main task might not have subtasks.

Parameters:

subTaskName - the name (or description) of the subtask

worked

void worked(int work)

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

Parameters:

work - the number of work units just completed