Local variable modification/access events in JPDA?

Dear Folks,
I am wondering if I can monitor modification/access events for local variables in JPDA. I used to use JDI as a tool to implement my project, but unfortunately there were only modification/access events for fields. Could someone tell me whether JVMTI (or any other tool from Sun) supports this?
Another problem when I was using JDI is that given an ObjectReference, I was not able to retrieve the underlying object in the target VM? Does there exist any solution to this problem?
Thank you very much for your help!
Sunny

Hello,
There are no such JVM TI watchpoint events yet.
Please, see the RFE:
4228507 Add local variable and array element watchpoints
Thanks,
Serguei

Similar Messages

Problem using local variable in event loop

I have a state machine from which I want to monitor various controls, including "Start" and "Stop" buttons. Not every state needs to monitor the controls. At present, most states run timed loops. In the first state that reads the front panel, I have an Event structure (inside a While loop) that monitors the various controls' Change Value events. For numeric controls, I update variables (in shift registers) as needed. The "Start" button is used to end the While loop controlling the Event structure, allowing the State to exit to the next state.
My problem comes in subsequent states that employ this same idea. Here, I put a Local Variable bound to the Start button and use the same code, but it frequently happens that when I enter this particular state, I cannot "turn on" the control -- I push the button, but it stays off. Curiously, if it was On when I enter, I can turn it off, but then I'm stuck not being able to turn it on.
I mocked up a very simply routine that illustrates this. There are two sequences (corresponding to the two states). Both use an Event loop with a local variable bound to my Stop button (really this is an LED control with custom colors). I've deliberately moved the "initialization" (the declaration of the control in the block diagram) out of the Event loops -- putting it inside the first loop modifies the behavior in another strange way.
Here's my thinking on how I would expect this to work: The code outside Event Loop 1 should have little effect. Assume the Stop button is initially Off. You will "sit" in Event Loop 1 until you push the Stop button, changing its value to True; this value will be passed out of the Event case and cause the first While loop to exit. You now enter the second sequence. As I understand the Exit tunnel, it defaults to "False", so I'd expect to stay in the second Event loop until I turn the Stop button from On to Off, which will pass out a False, and keep me in the While for one more button push. However, this doesn't happen -- I immediately exit, as though the "True" value of the Stop local variable is being seen and recognized by the Event loop (even though it hasn't changed, at least not in the context of this second loop).
An even more curious thing occurs if I start this routine with the Stop button turned on. Now I start in my Event loop waiting for a change, but this time the change will be from On to Off, which won't cause an exit from the frame. This will be reflected by having the While loop count increment. We should now be in the state of the example above, i.e. in an Event loop waiting for the control to be pushed again, and turned On. However, clicking the control has no effect -- I cannot get it to "turn on".
Where am I going astray in my thinking? What is it about this method of doing things that violates the Labview paradigm? As far as I can tell, what I'm doing is "legal", and I don't see the flaw in my reasoning, above (of course not -- otherwise I'd have fixed it myself!). Note that because I'm using local variables inside Event loops (and I'm doing this because there are two places in my code where I want to do such testing), the Stop control is not latching (as required). Is there something that gets triggered/set when one reads a latched control? Do I need to do this "manually" using my local variable?
I'll try to attach the simple VI that illustrates this behavior.
Bob Schor
Attachments:
Simple Stop Conundrum.vi ‏14 KB

altenbach wrote:
Ravens Fan wrote:
NEVER have multiple event structures that share the same events.
Actually, that's OK. NOT OK is having multiple event structures in the same sequence structure.
See also: http://forums.ni.com/ni/board/message?board.id=170&message.id=278981#M278981
That's interesting. I had always thought I read more messages discouraging such a thing rather than saying it was okay. Your link lead me to another thread with this message. http://forums.ni.com/ni/board/message?board.id=170&message.id=245793#M245793. Now that thread was mainly concentrating on registered user events which would be a different, but related animal.
So if you have 2 event structures they each have their own event queue? So if you have a common event, one structure pulls it off its event queue and it does not affect the other structure's event queue? I guess the inherent problem with this particular VI was that the second event structure locked the front panel. Since the code never got to that 2nd event structure because the first loop never stopped because the change was from true to false. After reading your post and the others, I did some experimentation and turned off the Lock front panel on the 2nd structure, and that prevented the lockup of the program.
Overall, the example VI still shows problems with the architecture and I think your answer should put the original poster on the right track. I think as a rule I would probably never put the same event in multiple structures, I feel there are better ways to communicate the same event between different parts of a program, but I learned something by reading your reply and about how the event structures work in the background. Thanks.

Custom class loader and local class accessing local variable

I have written my own class loader to solve a specific problem. It
seemed to work very well, but then I started noticing strange errors in
the log output. Here is an example. Some of the names are in Norwegian,
but they are not important to this discussion. JavaNotis.Oppstart is the
name of my class loader class.
java.lang.ClassFormatError: JavaNotis/SendMeldingDialog$1 (Illegal
variable name " val$indeks")
at java.lang.ClassLoader.defineClass0(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:502)
at java.lang.ClassLoader.defineClass(ClassLoader.java:431)
at JavaNotis.Oppstart.findClass(Oppstart.java:193)
at java.lang.ClassLoader.loadClass(ClassLoader.java:299)
at java.lang.ClassLoader.loadClass(ClassLoader.java:255)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:315)
at JavaNotis.SendMeldingDialog.init(SendMeldingDialog.java:78)
at JavaNotis.SendMeldingDialog.<init>(SendMeldingDialog.java:54)
at JavaNotis.Notistavle.sendMelding(Notistavle.java:542)
at JavaNotis.Notistavle.access$900(Notistavle.java:59)
at JavaNotis.Notistavle$27.actionPerformed(Notistavle.java:427)
JavaNotis/SendMeldingDialog$1 is a local class in the method
JavaNotis.SendMeldingDialog.init, and it's accessing a final local
variable named indeks. The compiler automatically turns this into a
variable in the inner class called val$indeks. But look at the error
message, there is an extra space in front of the variable name.
This error doesn't occur when I don't use my custom class loader and
instead load the classes through the default class loader in the JVM.
Here is my class loading code. Is there something wrong with it?
Again some Norwegian words, but it should still be understandable I hope.
     protected Class findClass(String name) throws ClassNotFoundException
         byte[] b = loadClassData(name);
         return defineClass(name, b, 0, b.length);
     private byte[] loadClassData(String name) throws ClassNotFoundException
         ByteArrayOutputStream ut = null;
         InputStream inn = null;
         try
             JarEntry klasse = arkiv.getJarEntry(name.replace('.', '/')
+ ".class");
             if (klasse == null)
                throw new ClassNotFoundException("Finner ikke klassen "
+ NOTISKLASSE);
             inn = arkiv.getInputStream(klasse);
             ut = new ByteArrayOutputStream(inn.available());
             byte[] kode = new byte[4096];
             int antall = inn.read(kode);
             while (antall > 0)
                 ut.write(kode, 0, antall);
                 antall = inn.read(kode);
             return ut.toByteArray();
         catch (IOException ioe)
             throw new RuntimeException(ioe.getMessage());
         finally
             try
                if (inn != null)
                   inn.close();
                if (ut != null)
                   ut.close();
             catch (IOException ioe)
     }I hope somebody can help. :-)
Regards,
Knut St�re

I'm not quite sure how Java handles local classes defined within a method, but from this example it seems as if the local class isn't loaded until it is actually needed, that is when the method is called, which seems like a good thing to me.
The parent class is already loaded as you can see. It is the loading of the inner class that fails.
But maybe there is something I've forgotten in my loading code? I know in the "early days" you had to do a lot more to load a class, but I think all that is taken care of by the superclass of my classloader now. All I have to do is provide the raw data of the class. Isn't it so?

Local variable can't be accessed from inner class ???????? Why ??????

Plesae help, help, help. I have no idea what to do with this bug.........
<code>
for ( int i = 0; i <= 2; i++ ) {
for ( int j = 0; j <= 2; j++ ) {
grids[i][j] = new MyButton ();
grids[i][j].setBorder(but);
getContentPane().add(grids[i][j]);
MyButton sub = grids[i][j];
sub.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if ( sub.getState() == 0 ) {
     sub = new MyButton( (Icon) new ImageIcon(imageFile));
     if ( imageFile.equals("cross.jpg") ) {
          sub.changeState(1);
     else {
          sub.changeState(2);
</code>
The compiler complains that "sub" is in the inner class, which is the ActionListener class, must be declared final. Please tell me what to do with it. I want to add an ActionListener to each MyButton Object in the array. Thanks ......

OK, now I changed my code to this :
for ( int i = 0; i <= 2; i++ ) {
for ( int j = 0; j <= 2; j++ ) {
    grids[i][j] = new MyButton ();
    grids[i][j].setBorder(but);
    getContentPane().add(grids[i][j]);
    grids[i][j].addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent e) {
        if ( grids[i][j].getState() == 0 ) {
           grids[i][j] = new MyButton( (Icon) new ImageIcon(imageFile));
          if ( imageFile.equals("cross.jpg") ) {
           grids[i][j].changeState(1);
          else {
          grids[i][j].changeState(2);
[/cpde]
Thanks for your advice !!!!!!
Now the compiler says that i and j are local variables accessed from inner classes, needs to be declared final. How can I solve this then ???

Inner class inside a method - how does it access method's local variable?

hello All:
I've learnt that, an inner class, if defined inside a method, it can access the method's local variables, only when they are defined as "final".
Anyone can help explain the rationale behind it?
Thanks a lot!
Sway

fathomBoat wrote:
In java, everything is about pass-by-reference.
Wrong! Nothing in Java is ever pass-by-reference.
Java uses pass-by-value everywhere.
It makes sense to me if the reason of enforcing a variable to be "final" is to prevent it being messed up.No, the reason is that a copy is made and if the variable weren't final then it could change later on and the developer could be confused because his inner class didn't "see" that change.
The variable being final prevents that scenario.
However, if a copy of the variable is made inside the inner class, i dont see how possible it could affect variables outside of class?Such a copy is made, but the language designers wanted to hide that fact from the developer. By forcing all accessed variables to be declared final the developer has no way to realize that he's actually working on a copy.

Local variable event structure

Hi,
I am using an array control and event structure for detecting changes in the array value.
At first,I have performed changes in the array(during runtime) and the event structure detected it.
The next step was adding a parallel while loop in which I am writing to the control array(using local variable).
During the runtime the layout of the array indeed changed,but the event structure didn't detect it.
I have attached 2 figures :1)The loop of the event structure 2)the parallel loop.
Is it possible working in such way?
How can I make the event structure detect changes the software performed in the control array?
Thanks,
Leonid
Solved!
Go to Solution.
Attachments:
event.PNG ‏43 KB
update.PNG ‏34 KB

This is a long discussion about "red flags"
Norbert
CEO: What exactly is stopping us from doing this?
Expert: Geometry
Marketing Manager: Just ignore it.

Local variable accessed within inner class

Hey everybody,
My program keeps telling me that it wont work because one of my methods is calling a local variable inside an inner class. Does anyone know what this means and how to fix it?
Heres the code:
public class SliderExample extends JPanel{
int value=0;
public SliderExample(int imw, int imh, Image img, BufferedImage buf, Graphics2D biCon){
super(true);
this.setLayout(new BorderLayout());
JSlider slider= new JSlider(JSlider.HORIZONTAL,0,imw,25);
slider.setMinorTickSpacing(10);
slider.setMajorTickSpacing(100);
slider.setPaintTicks(true);
slider.setPaintLabels(true);
JButton redraw= new JButton("Scroll");
redraw.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent ev){
reDraw(slider,img,buf,biCon,imw,imh);
add(slider,BorderLayout.CENTER);
add(redraw,BorderLayout.AFTER_LINE_ENDS);
public void reDraw(JSlider slid, Image im, BufferedImage bf, Graphics2D biC, int iw, int ih){
value=slid.getValue();
Graphics g= getGraphics();
g.drawImage(im,value,0,iw,ih,this);
g.drawImage(bf,value,0,iw,ih,this);
biC.drawImage(bf,value,0,iw,ih,this);
Any ideas???
THanks,
Rick

Its getting them from another class thats calling the mothod to construct the slider bar with dedraw button. Thats a pretty big class but I will post the code where I called the method:
public class Process extends JFrame implements MouseListener, MouseMotionListener{
private int [][] points;
private int [] lengths={0};
private int [] bin;
private String imstr;
private String imsav;
private int imgw=658;
private int imgh=512;
private int xArrayPos=0;
private int yArrayPos=0;
private int xpos=0;
private int ypos=0;
private int xprev;
private int yprev;
private int xadd;
private int yadd;
private String filstr;
Image image;
SimpleGUI gui;
BufferedImage buffer;
Graphics2D biContext;
Graphics2D g2;
BufferedImage last;
Graphics2D lastContext;
public Process(){
JFrame slideFrame = new JFrame("Please slide to scroll image");
slideFrame.setContentPane(new SliderExample(imgw, imgh,image,buffer,biContext));
slideFrame.pack();
slideFrame.setVisible(true);
Thats what anything having to do with that function in the other class that calls the Slider Class.
Do you know how I can fix this??
Thanks,
Rick

Thread Identification from Field/Local Variable

Hello,
If i have a code that executes multiple threads , can i identify which thread is operating on a certain field ?
Thanx

Watchpoint events contain the thread that accessed the field.
See
[http://java.sun.com/javase/6/docs/jdk/api/jpda/jdi/com/sun/jdi/request/EventRequestManager.html#createAccessWatchpointRequest(com.sun.jdi.Field)]
[http://java.sun.com/javase/6/docs/jdk/api/jpda/jdi/com/sun/jdi/event/AccessWatchpointEvent.html]
However, JDI does not support watchpoints on local variables.

Local variable needs to be declared final

This is the error code I am getting:
C:\javacode\Notepad>javac FinalProgram.java
FinalProgram.java:60: local variable textfield1 is accessed from within inner class; needs to be declared final
System.out.println("It is detected " + pressed +
textfield1);
^
1 error
Here is my code:
comments relevant to this topic are //ALL IN CAPS
import java.awt.*; //declare packages needed
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
import javax.swing.JMenuBar;
public class FinalProgram extends JFrame
    implements ActionListener {
static JFrame frame;
public void actionPerformed (ActionEvent e) {
      String answer = (e.getActionCommand());
         if (answer == "Get Data") {
          JInternalFrame iFrame = new JInternalFrame("Get Data . ", false, true, false, false);
          iFrame.setLayout(new GridLayout(8,2));
          JLabel label1 = new JLabel("First Name");
          JLabel label2 = new JLabel("Last Name");
          JLabel label3 = new JLabel("Street");
          JLabel label4 = new JLabel("City");
          JLabel label5 = new JLabel("State");
          JLabel label6 = new JLabel("Zip");
          JLabel label7 = new JLabel("Phone");
          JLabel label8 = new JLabel("Click Button to Submit Form -->");
          JTextField textfield1 = new JTextField(10);
          JTextField textfield2 = new JTextField(10);
          JTextField textfield3 = new JTextField(10);
          JTextField textfield4 = new JTextField(10);
          JTextField textfield5 = new JTextField(10);
          JTextField textfield6 = new JTextField(10);
          JTextField textfield7 = new JTextField(10);
          JButton button1 = new JButton("Submit Data");
          //textfield1.addActionListener(this);
          textfield1.addActionListener(this);
          textfield2.addActionListener(this);
          textfield3.addActionListener(this);
          textfield4.addActionListener(this);
          textfield5.addActionListener(this);
          textfield6.addActionListener(this);
          textfield7.addActionListener(this);
          button1.addActionListener(new ActionListener() { //start button1.addActionListener
          public void actionPerformed(ActionEvent a) { //start button1 actionPerformed
                    String pressed = ((JButton) a.getSource()).getText();
                    System.out.println("button press is detected " + pressed + textfield1); //THIS SYSTEM OUT PRINT IS A TEST, IT WORKS WHEN I DON'T HAVE THE "+ textfield1" PART, IT GIVES ME THE ERROR MESSAGE POSTED ABOVE ABOUT DECLARING IT FINAL.
I'M A BEGINNER, MY GOAL HERE, IN EASY ENGLISH, IS TO GRAB THE DATA FROM EACH TEXTFIELD AND STORE THEM IN VARIABLES, OR MORE IDEALLY IN AN ARRAY SO THAT THE REST OF MY CODE BELOW CAN WRITE THEM TO FILE, I'VE BEEN TRYING THE PAST FEW DAYS ON THIS EXPERIMENTING AND ANY SUGGESTIONS WOULD BE APPRECIATED
          try {
               String directoryName = "c:\\javacode\\Notepad";
               String fileName = "program.txt";
               File output = new File(directoryName,fileName);
               output.createNewFile();
          if (! output.isFile()) {
               System.out.println("File creation of" + output.getPath() + "failed");
        return;
          BufferedWriter out = new BufferedWriter(new FileWriter(output.getPath(), true));
          String[] text = {"This is the text that will be written. \r", //we pass an array, which holds the text to append to the file
                "The text will be written to the file \r",
                "in append mode. If the file does not \r",
                "exist it will be created.\r"}; //WHAT YOU SEE HERE IS JUST A TEST, IN PLACE, I WOULD LIKE TO HAVE THE INFORMATION FOR MY TEXTFIELDS SO THAT I CAN PASS THEM THROUGH A FOR LOOP AS BELOW AND WRITE DATA FOR EACH OF THE TEXTFIELDS TO MY EXTERNAL TEXT FILE
                for(int i = 0; i < text.length; i++) { //using the length of the text message we use out.Write() to write out the data. Notice that all of the code is placed into a try-catch block so we can check for any IOExceptions that occur
       out.write(text[i] + "\n");
          //Here I create the code to grab the actions(grab the text) from the textFields and store them into variables OR into an array
          //after I have created my container to hold the information for my various textFields, then I want to create a for loop to go through each textField and write that information to a text file, separating each textField on its own line
     out.close();
     catch(IOException d) {
     System.out.println("Error writing to file " + d);
               } //end button1.addActionListener
          } //end button1 actionPerformed
          );     //end actionListener statement
          //textfield1.setSize(10, 10);
          iFrame.add(label1);
          iFrame.add(textfield1);
          iFrame.add(label2);
          iFrame.add(textfield2);
          iFrame.add(label3);
          iFrame.add(textfield3);
          iFrame.add(label4);
          iFrame.add(textfield4);
          iFrame.add(label5);
          iFrame.add(textfield5);
          iFrame.add(label6);
          iFrame.add(textfield6);
          iFrame.add(label7);
          iFrame.add(textfield7);
          iFrame.add(label8);
          iFrame.add(button1);
          iFrame.setSize(200, 500);
          iFrame.setVisible(true);
          add(iFrame);
          if (answer == "Display Data") {
          JInternalFrame iFrame = new JInternalFrame("Display Data . ", false, true, false, false);
          JTextArea text = new JTextArea();
          JScrollPane scroller = new JScrollPane();
          scroller.getViewport().add(text);
          iFrame.getContentPane().add(scroller);
          iFrame.setSize(200, 150);
          iFrame.setVisible(true);
          add(iFrame);
public FinalProgram() {
    super ("Menu Example");
    JMenuBar jmb = new JMenuBar();
    JMenu file = new JMenu("Functions");
    JMenuItem item;
    file.add(item = new JMenuItem("Get Data"));
    item.addActionListener (this);
    file.add(item = new JMenuItem("Display Data"));
    item.addActionListener (this);
    jmb.add(file);
    addWindowListener(new ExitListener());
     setJMenuBar (jmb);
    public static void main(String[] args) {
        FinalProgram window = new FinalProgram();
        window.setTitle("Final Program");
        window.setSize(600, 600);
        window.setVisible(true);
}

hi,
Updated Code,
import java.awt.*; //declare packages needed
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
import javax.swing.JMenuBar;
public class FinalProgram extends JFrame
    implements ActionListener {
static JFrame frame;
          JLabel label1 = new JLabel("First Name");
          JLabel label2 = new JLabel("Last Name");
          JLabel label3 = new JLabel("Street");
          JLabel label4 = new JLabel("City");
          JLabel label5 = new JLabel("State");
          JLabel label6 = new JLabel("Zip");
          JLabel label7 = new JLabel("Phone");
          JLabel label8 = new JLabel("Click Button to Submit Form -->");
          JTextField textfield1 = new JTextField(10);
          JTextField textfield2 = new JTextField(10);
          JTextField textfield3 = new JTextField(10);
          JTextField textfield4 = new JTextField(10);
          JTextField textfield5 = new JTextField(10);
          JTextField textfield6 = new JTextField(10);
          JTextField textfield7 = new JTextField(10);
          JButton button1 = new JButton("Submit Data");
public void actionPerformed (ActionEvent e) {
      String answer = (e.getActionCommand());
         if (answer == "Get Data") {
          JInternalFrame iFrame = new JInternalFrame("Get Data . ", false, true, false, false);
          iFrame.setLayout(new GridLayout(8,2));
          //textfield1.addActionListener(this);
          textfield1.addActionListener(this);
          textfield2.addActionListener(this);
          textfield3.addActionListener(this);
          textfield4.addActionListener(this);
          textfield5.addActionListener(this);
          textfield6.addActionListener(this);
          textfield7.addActionListener(this);
          button1.addActionListener(new ActionListener() { //start button1.addActionListener
          public void actionPerformed(ActionEvent a) { //start button1 actionPerformed
                    String pressed = ((JButton) a.getSource()).getText();
                    System.out.println("button press is detected " + pressed + textfield1.getText());
          try {
               String directoryName = "c:\\javacode\\Notepad";
               String fileName = "program.txt";
               File output = new File(directoryName,fileName);
               output.createNewFile();
          if (! output.isFile()) {
               System.out.println("File creation of" + output.getPath() + "failed");
        return;
          BufferedWriter out = new BufferedWriter(new FileWriter(output.getPath(), true));
          String[] text = {"This is the text that will be written. \r", //we pass an array, which holds the text to append to the file
                "The text will be written to the file \r",
                "in append mode. If the file does not \r",
                "exist it will be created.\r"}; //WHAT YOU SEE HERE IS JUST A TEST, IN PLACE, I WOULD LIKE TO HAVE THE INFORMATION FOR MY TEXTFIELDS SO THAT I CAN PASS THEM THROUGH A FOR LOOP AS BELOW AND WRITE DATA FOR EACH OF THE TEXTFIELDS TO MY EXTERNAL TEXT FILE
                for(int i = 0; i < text.length; i++) { //using the length of the text message we use out.Write() to write out the data. Notice that all of the code is placed into a try-catch block so we can check for any IOExceptions that occur
       out.write(text[i] + "\n");
          //Here I create the code to grab the actions(grab the text) from the textFields and store them into variables OR into an array
          //after I have created my container to hold the information for my various textFields, then I want to create a for loop to go through each textField and write that information to a text file, separating each textField on its own line
     out.close();
     catch(IOException d) {
     System.out.println("Error writing to file " + d);
               } //end button1.addActionListener
          } //end button1 actionPerformed
          );     //end actionListener statement
          //textfield1.setSize(10, 10);
          iFrame.add(label1);
          iFrame.add(textfield1);
          iFrame.add(label2);
          iFrame.add(textfield2);
          iFrame.add(label3);
          iFrame.add(textfield3);
          iFrame.add(label4);
          iFrame.add(textfield4);
          iFrame.add(label5);
          iFrame.add(textfield5);
          iFrame.add(label6);
          iFrame.add(textfield6);
          iFrame.add(label7);
          iFrame.add(textfield7);
          iFrame.add(label8);
          iFrame.add(button1);
          iFrame.setSize(200, 500);
          iFrame.setVisible(true);
          add(iFrame);
          if (answer == "Display Data") {
          JInternalFrame iFrame = new JInternalFrame("Display Data . ", false, true, false, false);
          JTextArea text = new JTextArea();
          JScrollPane scroller = new JScrollPane();
          scroller.getViewport().add(text);
          iFrame.getContentPane().add(scroller);
          iFrame.setSize(200, 150);
          iFrame.setVisible(true);
          add(iFrame);
public FinalProgram() {
    super ("Menu Example");
    JMenuBar jmb = new JMenuBar();
    JMenu file = new JMenu("Functions");
    JMenuItem item;
    file.add(item = new JMenuItem("Get Data"));
    item.addActionListener (this);
    file.add(item = new JMenuItem("Display Data"));
    item.addActionListener (this);
    jmb.add(file);
    addWindowListener(new ExitListener());
     setJMenuBar (jmb);
    public static void main(String[] args) {
        FinalProgram window = new FinalProgram();
        window.setTitle("Final Program");
        window.setSize(600, 600);
        window.setVisible(true);
class ExitListener extends WindowAdapter {
public void windowClosing(WindowEvent event) {
    System.exit(0);
}

How to set multple values in cluster with local variable?

Hello all,
Ok, I've made my way through Labview for everyone, and have some basic concepts down. I can see with a cluster, if acting directly upon it, you can unbundle, change values, rebundle, etc.
I'm trying something a bit more complex...and just not sure how to get started on this.
I have a drop down menu ring. I have set this up as a typedef, with 4 values. I have used this typedef 7 times, plus some LED bools, in a cluster. I have made this cluster a typedef.
So, in my main vi I"m starting to design, I've set up an example posted here....and in it, I have two instantiations of the cluster typedef, Left Selector and Right Selector.
I have dropped into this vi, a copy of the menu ring typedef (same typedef as in the clusters, same values)....called reset all tubes.
I'm trying now, to figure out how, with an event on the change of value for 'reset all tubes'....that I can start with the left selector, and change all the tubes (these are the menu ring selector) to the same value as what has been selected with the 'reset all tubes' menu ring.
I've created a local variable for the left selector. It is set to read values. (I'll be doing the same with the right one too, but just starting with the left).
In examples I've seen where directly accessing a cluster, you could unbundle the cluster...loop through and change the values...maybe pull out all of the 'tubes' into an array and move through that to update the values. And when you bundle or unbundle the cluster...you can see the values, etc, when you stretch them out on the block diagram.
With the local variable..I can't see to 'stretch' it out like I was expecting..so I can access the values for the 'tubes'...and set them all to the value of the 'reset all tubes' ring menu value.
Can someone put me on the path on the best way to do this....or is there a structure of component I'm missing here ? Am I on the right track to begin with here?
This would seem pretty basic to me, but I'm just missing something here on how to start...
Thank you in advance,
cayenne
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Attachments:
example_select_dropdown.ctl ‏5 KB
public_selector_cluster.ctl ‏6 KB
laptop_test_public.vi ‏12 KB

nathand wrote:
You can't do this with a for loop the way the cluster is structured, but why make it so complicated? Just bundle the new value into the cluster as shown below:
If you do want to use a for loop, consider restructuring your cluster. Group the ring and a boolean into a cluster, then drop 7 of those into the selector cluster. Then you can use "cluster to array" and "array to cluster" since all elements in the outer cluster will be of the same type.
Also, be careful using rings as type definitions. You probably want to use an enumeration instead. The items in a ring do not update when you update the type definition because they're considered to be cosmetic; the items in an enumeration type definition do update, because the items in an enumeration are considered part of the data type.
Oh my goodness!!
What was MUCH easier than I was trying to make it!!
I was attempting to do this reset, in an incremental fashion, as that later, I'm going to need to change values in this cluster by individual elements....and was using this as a way to try to understand how to iterate between cluster elements, and change the values of each one.
This solution works much better for this 'reset' all solution.
One question on this....with regard to the enum vs the ring menu.
I was actually going to go with the enum, however, I could not find a way to make it LOOK like the ring menu...with the arrow to the side that a user would know to click to present the menu list of choices.
I see with the enum, that you can remove the increment/decrement indicator.....and if the user clicks the control, it will indeed pop up a menu of choices...but there is no 'arrow' on that control to indicate to the user that it is a menu choice there.....
Is there a way to make and enum look like a ring with the "drop down menu" control look?
Again, thank you !!
This helps!
C

Local variable doesn't update

hello,
in the example below the upper loop doesn't always update the value of the stop-control. why is that?
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local variable .jpg ‏14 KB

That "solution" is no better than your original. Using a property node instead of a local variable gains you absolutely nothing. A property node requires a thread switch to the user interface thread. In some cases this can cause huge performance impacts. I don't know why you don't want to use an event structure. Are you using LabVIEW Base which has no access to event structures? If you must use loops, then a better way to handle a loop that has a long loop time is to actually have the loop time short and then use a case structure to determine if it's time to execute the loop.
Something like this, for example
Attachments:
parallel loops MOD.vi ‏14 KB
parallel loops MOD_BD.png ‏25 KB

How can I Change data in a type def control containing a Xcontrol with a local variable

Hello
I made a Xcontrol and I inserted this control in a type def.
When I want to change the control's data with a local variable in a VI, the VI change nothing. The change of data isn't perform
How can I correct this issue?
Thanks for your help
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Hello,
What's your LabVIEW version ? Do you have a simple example program which demonstrates this behavior ?
I found another discussions related to your issues with Xcontrols:
updating type defs in Xcontrol Facade
No Data Change event generated for a XControl in a Type Def
XControl facede.vi
Hope this helps.
Regards,
Steve M.
National Instruments France
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Inserting in the UUT_Results table a value that we read from our data base from a local variable

We would like to include in the UUT_Results table a value that we read from our data base into a local variable during the execution of our sequence file. We found that by modifying the configure database options we were able to add a column for this variable, but the local variable was not available to be placed into an expression for that column from the local variables or parameters. Is it possible to do this, and if so, how? Station Globals were available to be included in the expression, however the sequence file may be executed on more than one system which makes the Global unavailable on systems other than the one where the sequence file originated.

You can use the TestStand API to programmatically create global variables at runtime, thus ensuring their existence. For example, you could call Engine.Globals.SetValString("GlobalStringVariableName", PropOption_InsertIfMissing, "variable value")
Of course, if you need to test multiple UUTs in parallel, a single global is not sufficient. In that case you might consider adding the field you need to the UUT datatype in the process model. You could then access the field in your sequence via RunState.Root.Locals.UUT.YourNewField = YourNewValue.
If you also want your sequence to run without using a process model, you must check for the existence of the UUT before accessing it. You could use the expression function: PropertyExists("RunState.Root.Locals.UUT.YourNewFi
eld")

What is it about data types of local variables?

Hey there!
I'm trying hard to access the booleans, whose refnums got stored into an array. As the example show, everything's fine unless I start using local variables: I can access the data in the topmost FOR loop. As soon as variables come into play, it seems as if I have to explicitly typecast the data. Is it just me? There has to be a less complicated way... can anybody give me a hint?
Kind regards,
Severin
Attachments:
data types of local variables.jpg ‏96 KB
data types of local variables_7.11.vi ‏39 KB

Hi Severin,
The output from that property node is of variant data type. You can convert it to boolean by using the Variant to Data VI. See attached example
Sarah
Applications Engineer | National Instruments | UK & Ireland
Attachments:
data types of local variables_7.11.vi ‏41 KB

Resetting a variable in an event structure (dynamic event)

I'm working on moving an event structure into a sub VI. This means I have to register dynamic events.
The event structure is handling some button clicks. The state of the button (mechanical action = latch when released) resets itself automatically as long as the variable is placed within the value change case. Leaving the button in this case is not possible when the event structure is put in a sub VI and the variable is located in the parent VI. How do I make sure the button unlatches after clicking on it? I have attached an example where all the code is in one VI (the local variable must be moved outside the event structure in order for it to be moved into a sub VI). Any ideas?
If you open the VI and run it, you can click Start which will cause the counter to start incrementing. The button only unlatches as long as the variable is located in the value change case.
(Btw, how do you put images inline in a post?)
Rob
LV2011,LV2012,LV2013
Attachments:
img.png ‏18 KB
main.vi ‏17 KB

Race conditions are the primary reason not to do that. But since your treating your variable as a latch, I doubt your using the value you read from it anywhere, and in that case it can't create a race condition. There's also the possibility that the control's reference could become invalid. But since this is a sub VI of the control's VI that can't happen (even if it could you can check the error out of the value property node to see when it happens and deal with it).
I'm not sure about the flickering, Since I can't seem to duplicate it with a simple test case on my machine. It might related to whatever else you're doing in the event apart from reseting the value to false.

Local variable modification/access events in JPDA?

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