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Oct 16th, 2009

Re: Access Swing Component infinitely from a separate thread (without "freezing" the app)

Change this

Click to Expand / Collapse Quote originally posted by Clawsy ...

Java Syntax (Toggle Plain Text)
    usbThread thread = new usbThread();
 
    public detectUSB() {
        initComponents();
 
        thread.start();
 
 
        final JLabel label = lbl_status;
        final String text = thread.getThreadStatus();
 
        SwingUtilities.invokeLater(
                new Runnable() {
                    public void run() {
                        label.setText(text);
                        label.validate();
                        label.repaint();
                    }
                }
            );
    }
usbThread thread = new usbThread(); public detectUSB() { initComponents(); thread.start(); final JLabel label = lbl_status; final String text = thread.getThreadStatus(); SwingUtilities.invokeLater( new Runnable() { public void run() { label.setText(text); label.validate(); label.repaint(); } } ); }

to this

Java Syntax (Toggle Plain Text)
    public detectUSB() {
        initComponents();
    }
    public detectUSB() {
        initComponents();
    }

and change this

Quote ...

Java Syntax (Toggle Plain Text)
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new detectUSB().setVisible(true);
            }
        });
    }
public static void main(String args[]) { java.awt.EventQueue.invokeLater(new Runnable() { public void run() { new detectUSB().setVisible(true); } }); }

to this

Java Syntax (Toggle Plain Text)
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new detectUSB().setVisible(true);
            }
        });
        new usbThread(lbl_status).start();
    }
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new detectUSB().setVisible(true);
            }
        });
        new usbThread(lbl_status).start();
    }

and change this

Quote ...

Java Syntax (Toggle Plain Text)
public class usbThread extends Thread{
    public String status=".....";
    usbThread()
    {
 
    }
 
    String getThreadStatus()
    { 
      return this.status;
    }
 
    @Override
    public void run() {
        ....
        this.status="FindDrive: waiting for devices...";
            ....
                this.status="Drive "+letters[i]+" has been plugged in";
            else
                this.status="Drive "+letters[i]+" has been unplugged";
                ....
            }
            try { Thread.sleep(100); }
            catch (InterruptedException e) { /* do nothing */ }
        }
    }
public class usbThread extends Thread{ public String status="....."; usbThread() { } String getThreadStatus() { return this.status; } @Override public void run() { .... this.status="FindDrive: waiting for devices..."; .... this.status="Drive "+letters[i]+" has been plugged in"; else this.status="Drive "+letters[i]+" has been unplugged"; .... } try { Thread.sleep(100); } catch (InterruptedException e) { /* do nothing */ } } }

to this

Java Syntax (Toggle Plain Text)
public class usbThread extends Thread{
    private String status = ".....";
    private JLabel label;
    usbThread(JLabel label) {
        this.label = label;
    }
 
    private void postStatus() {
        SwingUtilities.invokeLater(
                new Runnable() {
                    public void run() {
                        label.setText(status);
                        label.validate();
                        label.repaint();
                    }
                }
            );
    }
 
    @Override
    public void run() {
        ....
        this.status="FindDrive: waiting for devices...";
        postStatus();
            ....
                this.status="Drive "+letters[i]+" has been plugged in";
            else
                this.status="Drive "+letters[i]+" has been unplugged";
                ....
            }
            postStatus();
            try { Thread.sleep(100); }
            catch (InterruptedException e) { /* do nothing */ }
        }
    }
public class usbThread extends Thread{
    private String status = ".....";
    private JLabel label;
    usbThread(JLabel label) {
        this.label = label;
    }

    private void postStatus() {
        SwingUtilities.invokeLater(
                new Runnable() {
                    public void run() {
                        label.setText(status);
                        label.validate();
                        label.repaint();
                    }
                }
            );
    }

    @Override
    public void run() {
        ....
        this.status="FindDrive: waiting for devices...";
        postStatus();
            ....
                this.status="Drive "+letters[i]+" has been plugged in";
            else
                this.status="Drive "+letters[i]+" has been unplugged";
                ....
            }
            postStatus();
            try { Thread.sleep(100); }
            catch (InterruptedException e) { /* do nothing */ }
        }
    }

Last edited by masijade; Oct 16th, 2009 at 7:13 am.

masijade

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Oct 16th, 2009

Re: Access Swing Component infinitely from a separate thread (without "freezing" the app)

Thefact is the plaggedIn variable and isDrivev[i] are always equal so you the code inside the for bloc is never executed:
if you try this:
if(drives[i].canRead()) {
this.status.............
}else{
this.status.......
}

moutanna

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Oct 16th, 2009

Re: Access Swing Component infinitely from a separate thread (without "freezing" the app)

THANK YOU SO MUCH FOR SOLVING MY PROBLEM. I guess not only me was searching for this.

One note for the master

: when said to add "new usbThread(lbl_status).start();" to the main function. You cannot cause main is static (you get build error). So I just started it after " initComponents();".

THANK YOU SO MUCH!

Clawsy

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Oct 16th, 2009

Re: Access Swing Component infinitely from a separate thread (without "freezing" the app)

Sorry, brainfart.

Starting after initComponents (if done within the SwingUtilities) is bad as you are kicking it off from the Swing Event Thread, and you should, really, avoid that, if possible. Try it this way. Remove the "detectUSB" constructor and then change the main as follows:

Java Syntax (Toggle Plain Text)
    public static void main(String args[]) {
        detectUSB dusb = new detectUSB();
        SwingUtilities.invokeLater(new Runnable() {
                public void run() {
                    dusb.initComponents().setVisible(true);
                }
            });
        new usbThread(dusb.lbl_status).start();
    }
    public static void main(String args[]) {
        detectUSB dusb = new detectUSB();
        SwingUtilities.invokeLater(new Runnable() {
                public void run() {
                    dusb.initComponents().setVisible(true);
                }
            });
        new usbThread(dusb.lbl_status).start();
    }

And, in any case, change the usbThread constructor as follows:

Java Syntax (Toggle Plain Text)
    usbThread(JLabel label) {
        this.label = label;
        setDaemon(true);
    }
    usbThread(JLabel label) {
        this.label = label;
        setDaemon(true);
    }

To ensure that the thread dies properly.

Edit: And, not intending to nitpick, it is standard Java programming convention to capitalise Classes so those class names should be DetectUSB and USBThread.

Last edited by masijade; Oct 16th, 2009 at 9:55 am.

masijade

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Oct 16th, 2009

Re: Access Swing Component infinitely from a separate thread (without "freezing" the app)

Yes. Thank you

. These are really good hints and valuable advices. (but I put " new usbThread(lbl_status).start();" in formWindowOpened event cause... again: Builder said 'non-static variable lbl_status cannot be referenced from a static context'... sorry

). Thanks. Now I even optimized my application.

Clawsy

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