I'm new to Swing and I was trying to do this:
On pressing a JButton, the program will start iterating over hundreds of items, taking 1 second to process each one, and after finishing each one he should update a label to show the number of items already processed.
The problem is, the label's text is not updated until the cycle finishes iterating over all the items.
I searched online and apparently it's because this is running in the same thread, so I created a new thread to process the data and to update the variable to be used in the label (number of processed files).
But it didn't work. Then I even made another thread, which I start after the previous one, that just repaints the label. Still nothing works.
The code is like this:
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try { SwingUtilities.invokeLater(validateFiles); }
}); }
Runnable validateFiles = new Runnable() {
#Override
public void run() {
while(x_is_not_100) {
processLoadsOfStuff();
label.setText(x); }
}
};
Can you help me with this?
Simple - use a SwingWorker. For more information, read the Tasks that Have Interim Results tutorial.
Here's a pretty generic example that will use a JLabel to display counting from 0 to 30 -
public final class SwingWorkerDemo {
private static JLabel label =
new JLabel(String.valueOf(0), SwingConstants.CENTER);
public static void main(String[] args){
SwingUtilities.invokeLater(new Runnable(){
#Override
public void run() {
createAndShowGUI();
}
});
JLabelSwingWorker workerThread = new JLabelSwingWorker();
workerThread.run();
}
private static void createAndShowGUI(){
final JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(label);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private static class JLabelSwingWorker extends SwingWorker<Void, Integer>{
#Override
protected Void doInBackground() throws Exception {
for(int i = 1; i < 31; i++){
Thread.sleep(1000);
publish(i);
}
return null;
}
#Override
protected void process(List<Integer> integers) {
Integer i = integers.get(integers.size() - 1);
label.setText(i.toString());
}
}
}
The background processing must be done in a separate thread. But the label update must be done in the event dispatch thread.
So your code should look like this:
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
// start a new thread for the background task
new Thread(validateFiles).start();
});
}
Runnable validateFiles = new Runnable() {
#Override
public void run() {
while(x_is_not_100) {
processLoadsOfStuff();
// use SwingUtilities.invokeLater so that the label update is done in the EDT:
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
label.setText(x);
}
});
}
};
But you might want to use the SwingWorker class, which is designed to do that in a simpler way. Its documentation is very well done and contains examples.
Related
I have a JButton that will not allow me to perform the same action on any subsequent click on it after the first in the same Swing GUI instance.
JButton Run = new JButton("Run");
Run.setLocation(290, 70);
Run.setSize(120, 30);
buttonPanel.add(Run);
Run.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if (Run.isEnabled()) {
errorLabel.setText("");
Result result = JUnitCore.runClasses(Run.class);
errorMessageDisplay(result);
}
}
});
totalGUI.setOpaque(true);
return totalGUI;
}
So far I thought about and tried removing the JPanel and painting all of the buttons back on, and disabling/renabling buttons.
The errorMessageDisplay method is as follows:
public void errorMessageDisplay(Result resultPass) {
if (resultPass.getFailureCount() > 0) {
errorLabel.setForeground(Color.red);
errorLabel.setVisible(true);
errorLabel.setText(" Failed");
}
else {
errorLabel.setForeground(Color.green);
errorLabel.setText(" Passed");
errorLabel.setVisible(true);
}
}
At first glance, the JUnitCore.runClasses(Run.class); call is suspicous. Also, it would be good to know what does the errorMessageDisplay() do. I believe, the problem is with one of these methods.
You can verify this with the following experimental code. Just be careful not to push it into production.
JButton run = new JButton("Run");
run.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if (Run.isEnabled()) {
errorLabel.setText("");
System.out.println("Run action peformed.");
}
}
Update Since the errorMessageDisplay() looks okay, it's probably a Threading problem with JUniCore. Thus I'd try the following code:
final ExecutorService executor = Executors.newFixedThreadPool(5); // this runs stuff in background
JButton run = new JButton("Run");
// ..
run.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if (Run.isEnabled()) {
executor.execute(new Runnable() { // This is how we run stuff in background. You can use lambdas instead of Runnables.
public void run() {
final Result result = JUnitCore.runClasses(Run.class); // Run.class is different from the current JButton run.
SwingUtilities.invokeLater(new Runnable() { // Now we go back to the GUI thread
public void run() {
errorMessageDisplay(result);
}
});
}
});
}
});
My goal is creating a function that waits half second, set the jbutton's background to red for one second, and after this second the jbutton will return to normal. Cant make this work..
This is my Function
private void paint(final int num){
Timer timer = new Timer(500, new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (num == 1){
btn.setBackground(Color.black);
}
}
});
timer.start();
}
Start a 500ms timer that will do two things when it goes off:
- change the color to red
- start a 1s timer that will change the color to normal, when it goes off
Well, this would do it (note, you would probably want to put the code from the first sleep onwards into a timer or it's own thread in a real application to avoid blocking the thread running the code):
public static void main(String[] args) throws Exception {
final JFrame jf = new JFrame();
final JButton jButton = new JButton("Hello");
final Color originalBackground = jButton.getBackground();
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
jf.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
jf.getContentPane().add(jButton);
jf.pack();
jf.setVisible(true);
}
});
Thread.sleep(500);
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
jButton.setBackground(Color.RED);
}
});
Thread.sleep(1000);
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
jButton.setBackground(originalBackground);
}
});
I have a method like below.
ProgressWindow is a sub class of JFrame containing JProgressBar.
addProgress() increments a value in the JProgressBar.
If I call this method from a method in another class, a frame of ProgressWindow will show up but not JProgressBar and some JLabels inside the frame. They show up after the last line (System.out.println("finish")).
If I call this method in a main method in the class containing this method, then every component (Bar, labels...) instantly shows up.
What can I do for showing the window correctly?
static void search(){
ProgressWindow window = new ProgressWindow();
window.setVisible(true);
ExecutorService execs = Executors.newFixedThreadPool(Runtime
.getRuntime().availableProcessors());
Collection<Callable<Void>> processes = new LinkedList<>();
for (int i = 0; i < 100; i++) {
processes.add(new Callable<Void>() {
#Override
public Void call() throws Exception {
progressWindow.addProgress(); // increment progress value
return null;
}
});
}
try {
execs.invokeAll(processes);
} catch (Exception e) {
e.printStackTrace();
} finally {
execs.shutdown();
}
System.out.println("finish");
The main problem is you seem to be calling search from the context of the Event Dispatching Thread.
The problem occurs because you are using execs.invokeAll which blocks until all the callables have finished running.
This means that the EDT is unable to process new events in Event Queue, including repaint events, this is why your UI is coming to a stand still...
There are a number of issues you are now going to face...
You should never update/modify a UI component from any thread other than the EDT
You should block the EDT for any reason
You seem to want to know when the search is complete, so you know need some kind of event notification...
The first thing we need is some way to be notified that the search has completed, this means you can no longer rely on search returning when the search is complete...
public interface SearchListener {
public void searchCompleted();
}
Next we need an intermeditate search method that builds the UI and ensure that the search is launched within it's own Thread...
static void search(final SearchListener listener) {
final ProgressWindow window = new ProgressWindow();
window.setVisible(true);
Thread t = new Thread(new Runnable() {
#Override
public void run() {
search(listener, window);
}
});
t.start();
}
Then we need to modify the original search method to utilise the SearchListener interface to provide notification when the search is complete...
static void search(final SearchListener listener, final ProgressWindow window){
ExecutorService execs = Executors.newFixedThreadPool(Runtime
.getRuntime().availableProcessors());
Collection<Callable<Void>> processes = new LinkedList<>();
for (int i = 0; i < 100; i++) {
processes.add(new Callable<Void>() {
#Override
public Void call() throws Exception {
// This method needs to ensure that
// what ever it does to the UI, it is done from within
// the context of the EDT!!
progressWindow.addProgress();
return null;
}
});
}
try {
execs.invokeAll(processes);
} catch (Exception e) {
e.printStackTrace();
} finally {
execs.shutdown();
}
System.out.println("finish");
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
listener.searchCompleted();
}
});
}
Now, without the source code for addProgress, I might be tempted to use
processes.add(new Callable<Void>() {
#Override
public Void call() throws Exception {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
progressWindow.addProgress();
}
});
return null;
}
});
}
Instead...
Take a look at Concurrency in Swing for more details
Sounds like you what you're wanting to do is invoke the setVisible on the Swing UI thread, you can do this with invokeAndWait or invokeLater.
So something like:
final ProgressWindow window = new ProgressWindow();
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
window.setVisible(true);
}
});
I have a Jframe which is my application's window (appFrame in the following code) that contains a lot of logic and takes like 1 second or so to load. In the meantime I want to show my user a very nice loading frame (initFrame). However, when I run this code, the initFrame does appear but the text in a JLabel on it doesn't appear immediately - it actually doesn't appear at all in the brief moment till the app frame is loaded.
If i comment out all the appFrame, and only launch the initFrame, the text is loaded instantly, no waiting time at all. Why is this so? Might this be a concurrency issue?
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() { //as per best practice for concurrency in swing - see http://docs.oracle.com/javase/tutorial/uiswing/concurrency/
#Override
public void run() {
final JFrame initFrame = new InitFrame();
initFrame.setVisible(true);
final AppFrame appFrame = new AppFrame();
appFrame.setVisible(true);
initFrame.setVisible(false);
initFrame.dispose();
}
});
}
I would separate the frames' creation into two threads. The first, initializing InitFrame. Running this thread and calling isShowing() on the InitFrame object. When it returns true, run the second thread to initialize and show AppFrame.
This will force a happens before relationship between the visibility of the two frames.
class Main {
JFrame initFrame = null;
AppFrame appFrame = null;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
initFrame = new InitFrame();
initFrame.setVisible(true);
}
});
while(!initFrame.isShowing()) {
try {
Thread.sleep(50);
} catch (InterruptedException e) {
}
}
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
appFrame = new AppFrame();
appFrame.setVisible(true);
initFrame.setVisible(false);
initFrame.dispose();
}
});
}
}
Here's an example of what might be going wrong in your AppFrame.
You can run the test with threading:
java SplashTest true
or without
java SplashTest
When threading is enabled, you see the SplashFrame and AppFrame updating every 250ms, more or less.
When threading is not enabled, you get to see the SplashFrame with no components showing, the app 'hangs' for 4 seconds, then you see the AppFrame.
The example is somewhat contrived, but might give you some ideas.
Note that the SplashFrame has no 'direct' connection to the AppFrame. All communication is through the AppFrameWorkListener interface.
I've also put the 'work' in the AppFrame. But really if there is a lot of processing to be done it should be extracted out of the UI code, run in a separate Thread, and the AppFrame would be notified of progress by the task, in the same way as the SplashFrame currently is.
import javax.swing.*;
class SplashTest {
static boolean useThread = false;
public static void main(String[] args) {
// Pass true at the command line to turn on threading.
// No args, or any value other than true will turn off threading.
if (args.length > 0) {
useThread = new Boolean(args[0]);
}
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
SplashFrame splashFrame = new SplashFrame();
splashFrame.setVisible(true);
new AppFrame(splashFrame).setVisible(true);
}});
}
private static class BaseFrame extends JFrame {
public BaseFrame() {
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
setSize(200, 200);
setTitle(getClass().getSimpleName());
}
}
private static class SplashFrame extends BaseFrame implements AppFrameWorkListener {
JLabel status;
public SplashFrame() {
setLocation(0, 0);
status = new JLabel("Splash Frame");
getContentPane().add(status);
}
public void appFrameWorkStart() {
status.setText("Work started");
}
public void appFrameWorkProgress(long timeElapsed) {
status.setText("Work has taken " + timeElapsed + "ms so far");
}
public void appFrameWorkDone() {
// http://stackoverflow.com/questions/1234912/how-to-programmatically-close-a-jframe
setVisible(false);
dispose();
}
}
private static class AppFrame extends BaseFrame {
JLabel status;
AppFrameWorkListener listener;
public AppFrame(AppFrameWorkListener listener) {
setLocation(200, 200);
status = new JLabel("App Frame");
getContentPane().add(status);
this.listener = listener;
// None of this 'heavy lifting' should be in a constructor.
if (useThread) {
new Thread(new Runnable() {
#Override
public void run() {
doLotsOfWork(4);
}
}).start();
} else {
doLotsOfWork(4);
onWorkDone();
}
}
private void doLotsOfWork(int workLengthSeconds) {
// We're starting. Ensure onWorkStart is called on the EDT,
// as this method may be called from a different Thread.
invokeOnWorkStartOnEDT();
long start = System.currentTimeMillis();
// Hammer the CPU for "workLengthSeconds" number of seconds.
// And do some contrived progress reporting.
long workLengthMs = workLengthSeconds * 1000;
while (System.currentTimeMillis() - start < workLengthMs) {
long innerStart = System.currentTimeMillis();
// Consume 250ms CPU before issuing progress update.
while (System.currentTimeMillis() - innerStart < 250);
invokeOnWorkProgressOnEDT(System.currentTimeMillis() - start);
}
// We're done now. Ensure onWorkDone is called on the EDT,
// as this method may be called from a different Thread.
invokeOnWorkDoneOnEDT();
}
private void invokeOnWorkStartOnEDT() {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
onWorkStart();
}
});
}
private void invokeOnWorkProgressOnEDT(final long timeElapsed) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
onWorkProgress(timeElapsed);
}
});
}
private void invokeOnWorkDoneOnEDT() {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
onWorkDone();
}
});
}
private void onWorkStart() {
status.setText("Work Started");
if (null != listener) {
// Tell someone who's interested in the work status.
listener.appFrameWorkStart();
}
}
private void onWorkProgress(long timeElapsed) {
status.setText("Work has taken " + timeElapsed + "ms so far");
if (null != listener) {
// Tell someone who's interested in the work status.
listener.appFrameWorkProgress(timeElapsed);
}
}
private void onWorkDone() {
status.setText("Work Done");
if (null != listener) {
// Tell someone who's interested in the work status.
listener.appFrameWorkDone();
}
}
}
interface AppFrameWorkListener {
public void appFrameWorkDone();
public void appFrameWorkStart();
public void appFrameWorkProgress(long timeElapsed);
}
}
You Should use Java Thread and you can show an interactive Splash Screen (Custom made) to your user in the mean while while your code is generating whatever you want here is a tutorial just take a look
You should use Threads for good and efficient concurrency thats it
I am running a very heavy process under an anonymous SwingWorker thread. In the meantime, I'm reporting progress to the GUI using a progress bar. However, Swing threading is doing me in. It's simply not updating anything in time. I'm not sure how to do it, as I've tried updating the GUI from the SwingWorker thread, and outside, and both refuse to work.
How can I reliably update the Swing UI while a heavy worker thread is running?
Things I've tried
This does not work (with or without wrapping in the invokeLater command).
new LocalCompressor(compressor).execute();
while (!compressionDone) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
int percent = compressor.getPercentDone();
progressBar.setValue(percent);
statusLabel.setText(percent);
}
});
}
Additionally, attempting to update the UI from a concurrent measuring thread does not work:
class LocalCompressor extends SwingWorker<Void, Void> {
// [...]
public LocalCompressor(Compressor compressor) {
this.compressor = compressor;
// [...]
}
#Override
protected Void doInBackground() {
final Thread t1 = new Thread(new Runnable() {
#Override
public void run(){
compressor.compress();
}
});
final Thread t2 = new Thread(new Runnable() {
#Override
public void run() {
t1.start();
while (t1.isAlive()) {
updateUI(compressor.getPercentDone());
}
}
});
t2.start();
return null;
}
// [...]
}
You're not really using your SwingWorker. The worker already is a Thread for itself. If you have the possibility to put your long running code into the doInBackground(), put it there. Then just call publish(Integer) with your actual progress and process the chunks you get in the process(List<Integer>)-method. In process() you can update the gui, it's on the EDT.
EDIT:
Actually, what you're doing right now is polling in several-while loops, this is kinda power-consuming. That's why I think its better to you events in your algorithm, everytime you got a percent or everytime the loop starts a new round or something like that.
Did you try the very simple and basic way of using a SwingWorker? Like #Zhedar previously said, a SwingWorker already is a Thread for itself. So remove both your inner threads (t1, t2) and just use your time-consuming compress() method in doInBackground().
Something very basic like the following:
class LocalCompressor extends SwingWorker<Void, Integer> {
// .....
// Your constructor here
// .....
#Override
protected Void doInBackground() throws Exception {
compress();
return null;
}
#Override
protected void process(List<Integer> chunks) {
for (Integer chunk : chunks) {
progressBar.setValue(chunk);
statusLabel.setText(chunk);
}
}
}
Now this compress() method should be moved inside the SwingWorker and it must have somewhere a publish(), in your case it might be publish(getPercentDone()) or whatever.
private void compress() {
// .....
publish(getPercentDone());
// .....
}
This is how things are usually done with a SwingWorker.
Expanding on the answers and advice provided here already, here is one way to code it. I'm assuming the compressor itself has no ability to do callbacks but you can ask it for the percent done.
Within the swingworker thread (doInBackground) we start the real compression thread. Then start a polling loop in the background thread, to update the UI a few times a second. To notify the UI thread, call publish. This will cause the overridden method process to be called periodially in the event thread. From here we can safely update the progress bar and status label.
public class LocalCompressor extends SwingWorker<Void, Integer>
{
private Compressor compressor;
public LocalCompressor(Compressor compressor)
{
this.compressor = compressor;
// [...]
}
#Override
protected void done()
{
System.out.println("Compression is done. Going to do something with it...");
}
#Override
protected void process(List<Integer> chunks)
{
for (Integer percent : chunks)
{
progressBar.setValue(percent);
statusLabel.setText(percent);
}
}
#Override
protected Void doInBackground() throws Exception
{
final Thread t1 = new Thread(new Runnable()
{
#Override
public void run()
{
compressor.compress();
}
});
t1.start();
while (t1.isAlive())
{
int percentDone = compressor.getPercentDone();
publish(percentDone);
Thread.sleep(200);
}
return null;
}
}
You could employee a producer/consumer pattern...
Here's a really basic concept...
public class ProducerComsumer {
public static void main(String[] args) {
new ProducerComsumer();
}
public ProducerComsumer() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JPanel panel = new JPanel(new GridBagLayout());
panel.setBorder(new EmptyBorder(12, 12, 12, 12));
JProgressBar progressBar = new JProgressBar();
panel.add(progressBar);
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(panel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
Producer producer = new Producer();
producer.start();
Consumer consumer = new Consumer(producer, progressBar);
consumer.start();
}
});
}
public class Producer extends Thread {
private volatile float progress;
private volatile boolean done;
public Producer() {
setPriority(NORM_PRIORITY - 1);
setDaemon(true);
}
public float getProgress() {
return progress;
}
public boolean isDone() {
return done;
}
#Override
public void run() {
done = false;
for (int index = 0; index < Integer.MAX_VALUE; index++) {
progress = (float) index / (float) Integer.MAX_VALUE;
}
done = true;
System.out.println("All done...");
}
}
public class Consumer extends Thread {
private Producer producer;
private JProgressBar progressBar;
public Consumer(Producer producer, JProgressBar progressBar) {
setDaemon(true);
setPriority(NORM_PRIORITY - 1);
this.producer = producer;
this.progressBar = progressBar;
}
public JProgressBar getProgressBar() {
return progressBar;
}
public Producer getProducer() {
return producer;
}
#Override
public void run() {
while (!producer.isDone()) {
updateProgress();
try {
sleep(1000);
} catch (InterruptedException ex) {
Logger.getLogger(ProducerComsumer.class.getName()).log(Level.SEVERE, null, ex);
}
}
updateProgress();
}
protected void updateProgress() {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
int progress = Math.round(getProducer().getProgress() * 100f);
System.out.println("Update progress to " + progress);
getProgressBar().setValue(progress);
}
});
}
}
}
Have a play around with the Thread.setPriority values and see if it makes any difference
I'm assuming (ya know how that goes) that the call to LocalCompressor.execute() is blocking. If that's the case, your while loop won't run until it's all done, and then you're defeating the purpose of getting a steady stream of updates on your UI.
Give this, or something similar, a shot:
LocalCompressor comp = new LocalCompressor(compressor);
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
while (!compressionDone) {
int percent = compressor.getPercentDone();
progressBar.setValue(percent);
statusLabel.setText(percent);
}
}
});
comp.execute();
}