Using this class you can easily monitor tasks where you cannot * estimate the duration exactly.
* *A ProgressMonitor instance waits until the first time setProgress
* is called. When millisToDecideToPopup time elapsed the
* instance estimates the duration until the whole operation is completed.
* If this duration exceeds millisToPopup a non-modal dialog
* with a message and a progress bar is shown.
The value of millisToDecideToPopup defaults to
* 500 and millisToPopup to
* 2000.
ProgressMonitor instance. This is used to
* monitor a task and pops up a dialog if the task is taking a long time to
* run.
*
* @param component The parent component of the progress dialog or
* null.
* @param message A constant message object which works in the way it does
* in {@link JOptionPane}.
* @param note A string message which can be changed while the operation goes
* on.
* @param minimum The minimum value for the operation (start value).
* @param maximum The maximum value for the operation (end value).
*/
public ProgressMonitor(Component component, Object message,
String note, int minimum, int maximum)
{
// Set data.
this.component = component;
this.message = message;
this.note = note;
min = minimum;
max = maximum;
}
/**
* Hides the dialog and stops any measurements.
* *Has no effect when setProgress is not at least
* called once.
Updates the progress value.
* *When called for the first time this initializes a timer
* which decides after millisToDecideToPopup time
* whether to show a progress dialog or not.
If the progress value equals or exceeds the maximum * value the progress dialog is closed automatically.
* * @param progress New progress value. */ public void setProgress(int progress) { this.progress = progress; // Initializes and starts a timer with a task // which measures the duration and displays // a progress dialog if neccessary. if (timer == null && progressDialog == null) { timer = new Timer(25, null); timer.addActionListener(new TimerListener()); timer.start(); } // Cancels timer and hides progress dialog if the // maximum value is reached. if (progressBar != null && this.progress >= progressBar.getMaximum()) { // The reason for using progressBar.getMaximum() instead of max is that // we want to prevent that changes to the value have any effect after the // progress dialog is visible (This is how the JDK behaves.). close(); } } /** * Returns the minimum or start value of the operation. * * @return Minimum or start value of the operation. */ public int getMinimum() { return min; } /** *Use this method to set the minimum or start value of * your operation.
* *For typical application like copy operation this will be * zero.
* *Keep in mind that changing this value after the progress * dialog is made visible has no effect upon the progress bar.
* * @param minimum The new minimum value. */ public void setMinimum(int minimum) { min = minimum; } /** * Return the maximum or end value of your operation. * * @return Maximum or end value. */ public int getMaximum() { return max; } /** *Sets the maximum or end value of the operation to the * given integer.
* * @param maximum */ public void setMaximum(int maximum) { max = maximum; } /** * Returns whether the user canceled the operation. * * @return Whether the operation was canceled. */ public boolean isCanceled() { // The value is predefined to false // and changes only when the user clicks // the cancel button in the progress dialog. return canceled; } /** * Returns the amount of milliseconds to wait * until the ProgressMonitor should decide whether * a progress dialog is to be shown or not. * * @return The duration in milliseconds. */ public int getMillisToDecideToPopup() { return millisToDecideToPopup; } /** * Sets the amount of milliseconds to wait until the * ProgressMonitor should decide whether a progress dialog * is to be shown or not. * *This method has no effect when the progress dialog * is already visible.
* * @param time The duration in milliseconds. */ public void setMillisToDecideToPopup(int time) { millisToDecideToPopup = time; } /** * Returns the number of milliseconds to wait before displaying the progress * dialog. The default value is 2000. * * @return The number of milliseconds. * * @see #setMillisToPopup(int) */ public int getMillisToPopup() { return millisToPopup; } /** * Sets the number of milliseconds to wait before displaying the progress * dialog. * * @param time the number of milliseconds. * * @see #getMillisToPopup() */ public void setMillisToPopup(int time) { millisToPopup = time; } /** * Returns a message which is shown in the progress dialog. * * @return The changeable message visible in the progress dialog. */ public String getNote() { return note; } /** *Set the message shown in the progess dialog.
* *Changing the note while the progress dialog is visible * is possible.
* * @param note A message shown in the progress dialog. */ public void setNote(String note) { if (noteLabel != null) { noteLabel.setText(note); } else { this.note = note; } } /** * Internal method that creates the progress dialog. */ void createDialog() { // If there is no note we suppress the generation of the // label. Object[] tmp = (note == null) ? new Object[] { message, progressBar = new JProgressBar(min, max) } : new Object[] { message, noteLabel = new JLabel(note), progressBar = new JProgressBar(min, max) }; JOptionPane pane = new JOptionPane(tmp, JOptionPane.INFORMATION_MESSAGE); // FIXME: Internationalize the button JButton cancelButton = new JButton("Cancel"); cancelButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent ae) { canceled = true; } }); pane.setOptions(new Object[] { cancelButton }); // FIXME: Internationalize the title progressDialog = pane.createDialog(component, "Progress ..."); progressDialog.setModal(false); progressDialog.setResizable(true); progressDialog.pack(); progressDialog.setVisible(true); } /** An ActionListener implementation which does the measurements * and estimations of the ProgressMonitor. */ class TimerListener implements ActionListener { long timestamp; int lastProgress; boolean first = true; TimerListener() { timestamp = System.currentTimeMillis(); } public void actionPerformed(ActionEvent ae) { long now = System.currentTimeMillis(); if (first) { if ((now - timestamp) > millisToDecideToPopup) { first = false; long expected = (progress - min == 0) ? (now - timestamp) * (max - min) : (now - timestamp) * (max - min) / (progress - min); if (expected > millisToPopup) { createDialog(); } } else { // We have not waited long enough to make a decision, // so return and try again when the timer is invoked. return; } } else if (progressDialog != null) { // The progress dialog is being displayed. We now calculate // whether setting the progress bar to the current progress // value would result in a visual difference. int delta = progress - progressBar.getValue(); if ((delta * progressBar.getWidth() / (max - min)) > 0) { // At least one pixel would change. progressBar.setValue(progress); } } else { // No dialog necessary timer.stop(); timer = null; } timestamp = now; } } /** * Gets the accessible context. * * @return the accessible context. */ public AccessibleContext getAccessibleContext() { return accessibleContext; } }