Using a static variable declared in an applet in another class

Hi guys,
I created an applet and i want to use one of the static variables declared in teh applet class in another class i have. however i get an error when i try to do that...
in my Return2 class i try to call the variable infoPanel (declared as a static JPanel in myApplet...myApplet is set up like so:
public class myApplet extends JApplet implements ActionListener, ListSelectionListener
here are some of the lines causing a problem in the Return2 class:
myApplet.infoPanel.removeAll();
myApplet.infoPanel.add(functionForm2.smgframeold);
myApplet.infoPanel.validate();
myApplet.infoPanel.repaint();
here are some of the errors i get
dummy/Return2.java [211:1] package myApplet does not exist
myApplet.infoPanel.removeAll();
^
dummy/Return2.java [212:1] package myApplet does not exist
myApplet.infoPanel.add(functionForm2.smgframeold);
^
dummy/Return2.java [213:1] package myApplet does not exist
myApplet.infoPanel.validate();
^
dummy/Return2.java [214:1] package myApplet does not exist
myApplet.infoPanel.repaint();
^
please help! thanks :)

I don't declare any packages though....i think it just doesn't recognize myApplet for some reason..
other errors i got compiling are:
dummy/Return2.java [82:1] cannot resolve symbol
symbol : variable myApplet
location: class Return2
updateDesc.setString(3, myApplet.staticName);
I Don't get why i'm getting this error cuase they worked fine when myApplet was a standalone application, not an applet.
myApplet is in the same folder as Return2 and it compiles properly.

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Allasso
import javax.swing.*;
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}Edited by: Allasso on Feb 19, 2010 7:32 AM

Joerg22 wrote:
I don't get two independent frames, I only get one at a time.Correct. I got fooled by the method name.
Yeah, sorry about that...
But my basic statement is not shaken: You create and destroy several panels, whereas one panel would be sufficient.Yes, I am starting to see what you mean. See below:
Your additional actions (JFileChooser, JTextArea) are no hindrance for using a card layout, since I assume you will operate always from a specific panel.
Okay.
Still, it may turn out that you are most happy with your original design, for I assume the creation and destruction of multiple panels will not become a performance issue in your case.
This is largely an academic experience (even though I intend to use the program I am working on). Basically, I am exploring Java, and also trying to get a feel for what means are congruent with the spirit of OO programming. So if something is a performance issue, or any other issue, I am interested in knowing about it.
This is my first experience with GUI in any language, and essentially I am new to OO design as well. All of my previous experience has been with scripting.
Bye
JörgYour input is much appreciated, thanks.
Allasso
And now, this is what I have found so far, in regard to (not) creating and destroying panels. One note here as well, is that I found that if I placed my instructions for changing the panels (whether it be destroy/create or just changing the contents thereof) directly in the actionPerformed() method, rather than making them each separate methods and calling those methods from the actionPerformed() method, I did not have to declare the panel variables as static. Also, I declare the frame upon creation of it, rather than making it a field. So the result is I have eliminated all static fields.
For academic sake, however, I still do not understand why using frame.removeAll() behaves the way it does (see reply 2 above).
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
public class FrameDemo extends JFrame
    implements ActionListener {
    JLabel label1;
    JLabel label2;
    JButton button1;
    JButton button2;
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    FrameDemo(){};
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        if (e.getActionCommand().equals("openFrameTwo")) {
            panel1.removeAll();
            panel2.removeAll();
            label1 = new JLabel("Message for frame TWO");
            panel1.add(label1);
            panel1.revalidate();
            panel1.repaint();
            button2 = new JButton("quit");
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I wouldnot make anything other than the constants and the instance itself static. And I cant think of a reason wjy one would.

I want to use static variable instead of using variable in servlet context

Hi all,
In my web application i have to generate a unique Id.
For this, At the application startup time i am connecting to the database and getting the Id and placing it in the servlet context.
Every time i am incrementing this id to generate a unique id.
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tiru

There isn't a problem with this as long as you want to share the value of that variable with all requests. If this is read-only except when it is first set then you're fine. The only real issue will be how to initialize and/or reinitialize the variable. When the servlet is started, how will you get the value for the variable? If the servlet is shutdown and restarted (a possibility in any application server) how will you re-read the variable? You need to answer these questions to decide the best route. It may be as simple as a static initializer or it may be more complex like a synchronized method that is called to see if the variable is set.

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This is the error i get . If i understand the error correctly it says im using a static variable when i shouldnt be? Or is it the other way round? below the error is the actual code....
The error...
Googler.java:27: non-static variable this cannot be referenced from a static context
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          JButton submitButton = new JButton("Submit Query");
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thanks for the response.
I have already tried what you said but I tried it again anyway and i get the same error more less...
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Lee

Runtime error in linking with static variables....

Hi,
I am building a shared library which includes a compiled object generated from a class containing the static variables only and also I have another version of same class with same & some new static variables in it and using that to generate another shared library. Now when I tried to run a program
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Rajeev.

Not to worry...found the answer in another post. Seems like patches need to applied to the OS.

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Once again stuck in my own thinking, As per my knowledge there is a general error in java.
i.e. 'Non-static variable cant accessed from static context....'
Now the thing is that, When we are declaring any variables(non-static) and trying to access it within the same method, Its working perfectly fine.
i.e.
public class trial{
�� public static void main(String ar[]){ ////static context
�� int counter=0; ///Non static variable
�� for(;counter<10;) {
�� counter++;
�� System.out.println("Value of counter = " + counter) ; ///working fine
�� }
�� }
Now the question is that if we are trying to declare a variable out-side the method (Non-static) , Then we defenately face the error' Non-static varialble can't accessed from the static context', BUT here within the static context we declared the non-static variable and accessed it perfectly.
Please give your valuable suggestions.
Thanks,
Jeff

Once again stuck in my own thinking, As per my
knowledge there is a general error in java.
i.e. 'Non-static variable cant accessed from static
context....'
Now the thing is that, When we are declaring any
variables(non-static) and trying to access it within
the same method, Its working perfectly fine.
i.e.
public class trial{
�� public static void
main(String ar[]){ ////static context
�� int counter=0; ///Non
static variable
�� for(;counter<10;) {
�� counter++;
��
System.out.println("Value
of counter = " + counter) ; ///working fine
�� }
�� }
w the question is that if we are trying to declare a
variable out-side the method (Non-static) , Then we
defenately face the error' Non-static varialble can't
accessed from the static context', BUT here within
the static context we declared the non-static
variable and accessed it perfectly.
Please give your valuable suggestions.
Thanks,
JeffHi,
You are declaring a variable inside a static method,
that means you are opening a static scope... i.e. static block internally...
whatever the variable you declare inside a static block... will be static by default, even if you didn't add static while declaring...
But if you put ... it will be considered as redundant by compiler.
More over, static context does not get "this" pointer...
that's the reason we refer to any non-static variables declared outside of any methods... by creating an object... this gives "this" pointer to static method controller.

Best use of static constants in project level

Generally , we use magic numbers in loops & conditional statements in our code. But we have a better option of using final static variables(constants) instead of magic numbers. But the problem is if we need to use these constants in whole project then what is the best suitable place where we can put these constants in project.

At some part of the project everyone uses anyway.

Static variable doubt !!!

why the following code throws an error (Illegal start of expression )
public class samp
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In C you can have a static variable declared inside a function.
It is static, that is, retains the value between the calls, and it is declared in the function, hence it is seen only from there. In the following example both function have their own static i variables.
#include <stdio.h>
static int i=0;
int foo() {
static int i=100;
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int bar() {
static int i=200;
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int main() {
int x;
for(x=4;x<8;x++) printf("%d %d\n",x,foo());
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printf("%d\n",i);
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Equivalent of visual Basic static variable in LabVIEW

Hi all!
I am doing a project where I am counting the values. After i Close/Stop the program I want the value to be intact and continue with the last value.
I know this in Visual Basic. By using the Static variable we can retain the value even we close the program.
Kindly help..
Srikanth Chilivery,
Solved!
Go to Solution.

I have trouble believing that a static variable retains its value after the program is terminated. Once the program is released from memory, that static variable is gone. If you want to retain a value between closing and opening an application, you have to save it to disk in some way.
Are you working exclusively in the LabVIEW IDE or are you running EXEs? It sounds like you probably just want to use a Functional Global Variable/Action Engine.
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Using a static variable declared in an applet in another class

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