Techo

This is indeed somewhat tricky to find it out… I have understood at 
least some basics, and will try to explain it.

These animations are controlled by a background task. Background tasks 
should be used when time consuming tasks are made, which should not 
“freeze” the apllication. So a background task runs in the background, 
and is firing messages every now and then, while the main programming 
is still running and reacting. You can observe the task messages via a 
taskmonitor and than e.g. make changes to GUI components, like in this 
case the animated label (circling icon).

First of all, here is how a task is started. One way to do this is via 
actions (right click on a component and choose “set action”). Then you 
could start a task like this:

@Action
public Task myTask() {
return new 
ThisIsMyTask 
(org 
.jdesktop.application.Application.getInstance(yourappsnamehere.class));
}

The above sample shows how to start a task via an action, e.g. 
pressing a button. But you can also start a task manually, out of your 
application, without user interaction. I recently asked this question 
in this list and got following perfectly working answer:

Task mT = myTask();
ApplicationContext appC = Application.getInstance().getContext();
TaskMonitor tM = appC.getTaskMonitor();
TaskService tS = appC.getTaskService();
tS.execute(mT);
tM.setForegroundTask(mT);

This starts the task manually, by referring to the method shown in the 
first sample above. So, you have to have this method anyway, as far as 
I understood, but not necessarily declared as “action”.

Now, the Task class itself looks like the following:

private class ThisIsMyTask extends 
org.jdesktop.application.Task<Object, Void> {
ThisIsMyTask(org.jdesktop.application.Application app) {
super(app);

}

Furthermore, this class has some overidden methods. The most important 
one ist “doInBackground()”. This method contains the time consuming 
source code, which runs in the background, while the “main 
application” can still do other things (even waiting, e.g.).

@Override protected Object doInBackground() throws 
IOException {
// your heavy code here
return null;
}

Two more useful methods are “succeeded” and “finished”. succeeded is 
called, when the task has been successfully completed. Finished is 
called afterwards – but it is also called, when the task is “finished” 
by a cancel action for instance.

@Override protected void succeeded(Object result) {
// what should happen if task was successfully completed?
// insert here
}

@Override
protected void finished()
{
// when the task is finished, enter your code here. this method is 
even called, when
// a task was cancelled – if I understood right
super.finished();
}

Now, these are the tasks basics. Now to the animated cycling icon.

First of all, you have to store the single icons from the animations 
in an array. this is what you find in the samples from NetBeans:

// initiate animated busy-icons, which are animated when the 
thread is running
int busyAnimationRate = 
resourceMap.getInteger(“StatusBar.busyAnimationRate”);
for (int i = 0; i < busyIcons.length; i++) {
busyIcons[i] = resourceMap.getIcon(“StatusBar.busyIcons[" 
+ i + "]“);
}

Than you have to create a timer, which will start the animation once 
this timer is started. By creating this timer, it is not automatically 
running, just initiated…

// and create a busy-icon-timer
busyIconTimer = new Timer(busyAnimationRate, new 
ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
busyIconIndex = (busyIconIndex + 1) % busyIcons.length;
statusAnimationLabel.setIcon(busyIcons[busyIconIndex]);
}
});

The following lines just set the icon to the statusAnimationLabel (the 
one which show the cycling icon respectively a light grey one if 
nothing happens)

// initiate the idle icon and make it visible
idleIcon = resourceMap.getIcon(“StatusBar.idleIcon”);
statusAnimationLabel.setIcon(idleIcon);
progressBar.setVisible(false);

Now you have to create a task monitor, which observes the task. If I 
understood correctly, it is observing the current foreground task, so 
it might get in conflict with several background tasks at the same 
time – BUT I’M NOT SURE WITH THIS!

// connecting action tasks to status bar via TaskMonitor
TaskMonitor taskMonitor = new 
TaskMonitor 
(org 
.jdesktop 
.application.Application.getInstance(yourapp.class).getContext());

taskMonitor.addPropertyChangeListener(new 
java.beans.PropertyChangeListener() {
@Override
public void propertyChange(java.beans.PropertyChangeEvent 
evt) {
String propertyName = evt.getPropertyName();

And now come the events or messages which are fired by the background 
tasks. Here you decide, *what* should be done in such a case.

If I understood correctly, the “start” message is automatically fired 
by the task. So everything here will be done automatically when the 
background thread starts. In this case, the timer of the cycling icon 
is started, i.e. the icon is animated, and the progressbar is made 
visible (but not animated! there is no timer for the progressbar, it 
is just made visible; we come back to this later)

// when a background thread starts, start the busy 
icon animation
if (“started”.equals(propertyName)) {
if (!busyIconTimer.isRunning()) {
statusAnimationLabel.setIcon(busyIcons[0]);
busyIconIndex = 0;
busyIconTimer.start();
}
// and make the progressbar visible
progressBar.setVisible(true);
progressBar.setIndeterminate(true);

On the opposite, when the task is done, the “done” message is 
automatically fired. Accordingly, here the cycling icon timer is 
stopped and the progressbar is hidden

// when the thread finished working, stop animation, 
set idle icon
// and hide the progress bar
} else if (“done”.equals(propertyName)) {
busyIconTimer.stop();
statusAnimationLabel.setIcon(idleIcon);
progressBar.setVisible(false);
progressBar.setValue(0);

Now here comes a message which can be fired by your application, that 
means you can let this event happen. for instance, you can tell the 
task monitor out of your background task(!) that it is proceeding, 
i.e. firing a “progress” message. when the task monitor gets this 
message from your background task, you can insert your code here what 
should be done. typically, the progressbar is animated.

// if a progress was indicated during the thread 
using the
// “setProgress(value,min,max)” method, we can change 
the state
// of the progress bar here.
} else if (“progress”.equals(propertyName)) {
int value = (Integer)(evt.getNewValue());
progressBar.setVisible(true);
progressBar.setIndeterminate(false);
progressBar.setValue(value);
}
}
});
}
}

As you see, we have to important components here: statusAnimationLabel 
and progressBar. I don’t use the statusMessageLabel, so it’s missing 
here.

Now, once the background task is started (see very above), the icon is 
automatically animated, because we have started a timer which is 
responsible for the animation. but: the progressbar is only “animated” 
when we fire a progress event, which does not occur automatically - 
unlike “start” and “done” events/messages.

The “progress” event/message for the taskmonitor is simply fired when 
invoking the “setProgress” method!

This is what you could put in your doInBackground-Method in your task. 
Here’s an example for loading a file and animating the progressbar 
which show the process of the amount of loaded bytes:

// length of file
final long l = filepath.length();
// length of file in kilobytes
final long kbl = l / 1024;
// counter for progbar
long counter = 0;

fr = new FileReader(filepath);
buffer = new StringBuffer(“”);

for (int c; (c=fr.read()) != -1;) {
// append the bytes to the buffer
buffer.append((char)c);
// increase the counter for the progress 
bar
counter++;
// this method fires the “progress” event/message for the task 
monitor
setProgress(counter/1024,0,kbl);

that’s it. all your time consuming stuff should be put into the 
doInBackground method. If you like, you can animate a progress bar, if 
you don’t do this, you just have the cycling icon.

Now, since the initialization of the animated icons and progressbar 
needs known GUI components, usually all the init stuff is included in 
that class that contains also the components (statusMessageLabel, 
progressBar). But since I’m writing a desktop application which uses 
several forms with background tasks, I simply created an “task monitor 
initialisation class”. Whenever I have a form which needs background 
tasks, I simply pass the JLabel (statusAnimationLabel) and 
JProgressBar (progressbar) as parameters to the constructor:

CInitStatusBar isb = new 
CInitStatusBar( statusAnimationLabel, progressBar );

Now I only need to write my Task Class and start the task via an 
action or manually. But I don’t need to have the init stuff also 
included.

Here’s the complete class with the “externalised” taskmonitor-init:

public class CInitStatusBar {

private final Timer busyIconTimer;
private final Icon idleIcon;
private final Icon[] busyIcons = new Icon[15];
private int busyIconIndex = 0;

org.jdesktop.application.ResourceMap resourceMap = 
org 
.jdesktop 
.application 
.Application 
.getInstance 
(zettelkasten 
.ZettelkastenApp 
.class).getContext().getResourceMap(ZettelkastenView.class);

/**
* Initiates the status bar for background tasks.
* Catches messages from the doInBackground task
* and changes the progressbar state, the busy icon animation
* and – if necessary – the status message.
*/
CInitStatusBar( final javax.swing.JLabel statusAnimationLabel,
final javax.swing.JProgressBar progressBar ) {
/**
* This is pre-defined code taken from the NetBeans IDE
* Initiates some basic things for background tasks, like
* associating a statusbar and busy-icon to a background thread
*/

// initiate animated busy-icons, which are animated when the 
thread is running
int busyAnimationRate = 
resourceMap.getInteger(“StatusBar.busyAnimationRate”);
for (int i = 0; i < busyIcons.length; i++) {
busyIcons[i] = resourceMap.getIcon(“StatusBar.busyIcons[" 
+ i + "]“);
}
// and create a busy-icon-timer
busyIconTimer = new Timer(busyAnimationRate, new 
ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
busyIconIndex = (busyIconIndex + 1) % busyIcons.length;
statusAnimationLabel.setIcon(busyIcons[busyIconIndex]);
}
});

// initiate the idle icon and make it visible
idleIcon = resourceMap.getIcon(“StatusBar.idleIcon”);
statusAnimationLabel.setIcon(idleIcon);
progressBar.setVisible(false);

// connecting action tasks to status bar via TaskMonitor
TaskMonitor taskMonitor = new 
TaskMonitor 
(org 
.jdesktop 
.application 
.Application 
.getInstance(zettelkasten.ZettelkastenApp.class).getContext());

taskMonitor.addPropertyChangeListener(new 
java.beans.PropertyChangeListener() {
@Override
public void propertyChange(java.beans.PropertyChangeEvent 
evt) {
String propertyName = evt.getPropertyName();
// when a background thread starts, start the busy 
icon animation
if (“started”.equals(propertyName)) {
if (!busyIconTimer.isRunning()) {
statusAnimationLabel.setIcon(busyIcons[0]);
busyIconIndex = 0;
busyIconTimer.start();
}
// and make the progressbar visible
progressBar.setVisible(true);
progressBar.setIndeterminate(true);
// when the thread finished working, stop animation, 
set idle icon
// and hide the progress bar
} else if (“done”.equals(propertyName)) {
busyIconTimer.stop();
statusAnimationLabel.setIcon(idleIcon);
progressBar.setVisible(false);
progressBar.setValue(0);
// if a progress was indicated during the thread 
using the
// “setProgress(value,min,max)” method, we can change 
the state
// of the progress bar here.
} else if (“progress”.equals(propertyName)) {
int value = (Integer)(evt.getNewValue());
progressBar.setVisible(true);
progressBar.setIndeterminate(false);
progressBar.setValue(value);
}
}
});
}
}