Interfaces and final variables

So I understand that I am not supposed to put my final variables or constants into an interface, but then where?
I have 2 classes that implement an interface, and they both allow listerners to be added to them, through that interface. They both fire property events on the listener with the same property. Currently I just put the property id constants into one class and reference it from the other. But it appears to me the best place for the definition of these common properties is in the interface!?

So If you read over all the postings, you'll know exactly why they say, never to create classes for the purpose of grouping constants, it is confusing.
More explicitly, it is lazy. The reason you are grouping the constants has nothing to do with the relationship between the constants and their use within the program, you are grouping them because you are tired of typing a long declaration everytime you want to use them within the program. So, the overall design of your program is being warped by design decisions that are based on laziness.
The reason people put them in interfaces, "public interface Globals...", is so that importing that namespace through inheritance doesn't suck up that "valuable" superclass (which I will have to remember to rant about on some other thread). It is probably the case that the most efficient way to do this is to use static getters: getPI(), getOrigin(), getNewYears(), whatever. You will see an awful lot of constants that have been replaced over the years with getters. As the code matures, it isn't peculiar to see the flexibility of the programme being reduced or impeded by the constraints and constants implicit in the codesbase.
Andrew

Similar Messages

Problem with final variables and inner classes (JDK1.1.8)

When using JDK1.1.8, I came up with following:
public class Outer
    protected final int i;
    protected Inner inner = null;
    public Outer(int value)
        i = value;
        inner = new Inner();
        inner.foo();
    protected class Inner
        public void foo()
            System.out.println(i);
}causing this:
Outer.java:6: Blank final variable 'i' may not have been initialized. It must be assigned a value in an initializer, or in every constructor.
public Outer(int value)
^
1 error
With JDK 1.3 this works just fine, as it does with 1.1.8 if
1) I don't use inner class, or
2) I assign the value in initializer, or
3) I leave the keyword final away.
and none of these is actually an option for me, neither using a newer JDK, if only there is another way to solve this.
Reasons why I am trying to do this:
1) I can't use a newer JDK
2) I want to be able to assign the variables value in constructor
3) I want to prevent anyone (including myself ;)) from changing the value in other parts of the class (yes, the code above is just to give you the idea, not the whole code)
4) I must be able to use inner classes
So, does anyone have a suggestion how to solve this problem of mine? Or can someone say that this is a JDK 1.1.8 feature, and that I just have to live with it? In that case, sticking to solution 3 is probably the best alternative here, at least for me (and hope that no-one will change the variables value). Or is it crappy planning..?

You cannot use a final field if you do not
initialize it at the time of declaration. So yes,
your design is invalid.Sorry if I am being a bit too stubborn or something. :) I am just honestly a bit puzzled, since... If I cannot use a final field in an aforementioned situation, why does following work? (JDK 1.3.1 on Linux)
public class Outer {
        protected final String str;
        public Outer(String paramStr) {
                str = paramStr;
                Inner in = new Inner();
                in.foo();
        public void foo() {
                System.out.println("Outer.foo(): " + str);
        public static void main( String args[] ) {
                String param = new String("This is test.");
                Outer outer = new Outer(param);
                outer.foo();
        protected class Inner {
                public void foo() {
                        System.out.println("Inner.foo(): " + str);
} producing the following:
[1:39] % javac Outer.java
[1:39] % java Outer
Inner.foo(): This is test.
Outer.foo(): This is test.
Is this then an "undocumented feature", working even though it shouldn't work?
However, I assume you could
get by with eliminating the final field and simply
passing the value directly to the Inner class's
constructor. if not, you'll have to rethink larger
aspects of your design.I guess this is the way it must be done.
Jussi

Final attributes and local variables - performance ??

Hi all,
I and a colleague have done some performance testing regarding the use of final attributes and final local variables, e.g.
with final:
public class MyClass {
private final int i;
public final void myMethod() {
    final int j = 5;
    // do something with i and j
}vs. non-final:
public class MyClass {
private int i;
public final void myMethod() {
    int j = 5;
    // do something with i and j
}I couldn't find any speed differences in a small test program, but my colleague did so in his application. Who is right ??
Still, I will have do some formal testing next week and I will post the results.
I'd prefer the version using final anyway because I find it better readable, but the issue I am having is whether I'll spend 2-3 days going through the program making everything final or not.

I made some tests with final arguments to a method: I could not find any difference between final and non-final arguments. code is posted below
import java.io.*;
import java.net.*;
import java.rmi.*;
import java.util.*;
import javax.ejb.*;
import javax.naming.*;
import javax.rmi.PortableRemoteObject;
import junit.framework.*;
import junit.extensions.*;
public final class FinalVariablesTest extends TestCase /* from junit */ {
     * Constructors
    public FinalVariablesTest(String name) {
        super(name);
     * helper methods/classes
    protected void setUp() throws Exception {
        super.setUp();
    protected void tearDown() throws Exception {
        super.tearDown();
     * Test Suite
    public static void main(String[] args) {
     junit.textui.TestRunner.run(suite());
    public static Test suite() {
        return new TestSuite(FinalVariablesTest.class);
     * Test Cases
    /** tests the effect of passing an (final or non-final) int parameter
     to a method which uses the variable in a for loop.
     <p>
     Linux System:
     cat /proc/cpuinfo
     processor       : 0
     vendor_id       : GenuineIntel
     cpu family      : 6
     model           : 8
     model name      : Pentium III (Coppermine)
     stepping        : 1
     cpu MHz         : 501.146
     cache size      : 256 KB
     fdiv_bug        : no
     hlt_bug         : no
     sep_bug         : no
     f00f_bug        : no
     coma_bug        : no
     fpu             : yes
     fpu_exception   : yes
     cpuid level     : 2
     wp              : yes
     flags           : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov pat pse36 mmx fxsr xmm
     bogomips        : 999.42
     </pre>
     <p>
     Results:
     <pre>
     java version "1.4.0"
     Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-b92)
     Java HotSpot(TM) Client VM (build 1.4.0-b92, mixed mode)
     final     non-final
     498     500
     491     494
     491     493
     491     494
     534     494
     492     494
     491     494
     492     493
     491     494
     495     494
     4966     4944 (Totals)
     </pre>
    public final void testIntParametersToForLoop() {
     final int RUNS = 10;
     final int INNER = 1000000;
     final int OUTER = 10;
     System.out.println("-----------------------");
     System.out.println("testIntParametersToForLoop");
     for(int i=0; i<RUNS; i++) {
         outerFinalIntParametersToForLoop(INNER, OUTER);
         outerNonFinalIntParametersToForLoop(INNER, OUTER);
    private final void outerFinalIntParametersToForLoop(final int INNER,
                                   final int OUTER) {
     // with final var in for loop
     long start0 = System.currentTimeMillis();
     for(int i=0; i<OUTER; i++) {
         innerFinalIntParametersToForLoop(INNER * i);
     long end0 = System.currentTimeMillis();
     System.out.println("      final:       " +
                  ( end0 - start0 ) + " milliseconds");
    private final void outerNonFinalIntParametersToForLoop(final int INNER,
                                      final int OUTER) {
     // with non-final var in for loop
     long start1 = System.currentTimeMillis();
     for(int i=0; i<OUTER; i++) {
         innerNonFinalIntParametersToForLoop(INNER * i);
     long end1 = System.currentTimeMillis();
     System.out.println(" non final: " +
                  ( end1 - start1 ) + "       milliseconds");
    private final void innerFinalIntParametersToForLoop(final int INNER) {
     for(int i=0; i<INNER; i++) {
         int testVar = i * INNER;
    private final void innerNonFinalIntParametersToForLoop(int loops) {
     for(int i=0; i<loops; i++) {
         int testVar = i * loops;

Final variables and try blocks

If you tried to initialize a final variable within a try block, you would get a compile-time error.
Here's an example class:
class Example {
    private final String example;
    public Example() {
        try {
            example = "Example";
        } catch (Exception e) {
            // Just an example.
}Obviously you wouldn't need to try-catch something like this (it's a stupid example - I know) , but the point is, the code wouldn't compile, and would return an error saying something like "example may not have been initialized".
So I've got two questions. Why is this, and is there any way around it?
Thanks in advance :)

Why is thisThe actual error message is "The blank final field example may not have been initialized". The Java compiler insists that all the fields have some actual value when a constructor has done its thing. Nonfinal fields will have the "default" value of null, but this is not so for final fields: if they had a default value, you couldn't change them from that default because they're final!
Once you enter a try block the compiler has no way of knowing that the assignment line will ever get carried out. Some exception might occur and the example field would be left uninitialised ie having no value whatsoever, not even null.
is there any way around it?In the catch part you could throw the exception and let the caller deal with it.
Or you could try and assign some value to example within the catch part. Now the compiler will complain "The final field example may already have been assigned". Supposing you wanted it to end up as null in this case (it's not clear why though... But you may have a sensible "default" if for example a file can't be written to or some other exceptional state has occured)
class Example {
    private final String example;
    public Example() {
        String str;
        try {
            str = "Example";
        } catch (Exception e) {
            str = null;
        example = str;
}

Problem with final variables and inner classes

variables accessed by inner classes need to be final. Else it gives compilation error. Such clases work finw from prompt. But when I try to run such classes through webstart it gives me error/exception for those final variables being accessed from inner class.
Is there any solution to this?
Exception is:
java.lang.ClassFormatError: com/icorbroker/fx/client/screens/batchorder/BatchOrderFrame$2 (Illegal Variable name " val$l_table")
     at java.lang.ClassLoader.defineClass0(Native Method)
     at java.lang.ClassLoader.defineClass(ClassLoader.java:502)
     at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:123)
     at com.sun.jnlp.JNLPClassLoader.defineClass(Unknown Source)
     at com.sun.jnlp.JNLPClassLoader.access$1(Unknown Source)
     at com.sun.jnlp.JNLPClassLoader$1.run(Unknown Source)
     at java.security.AccessController.doPrivileged(Native Method)
     at com.sun.jnlp.JNLPClassLoader.findClass(Unknown Source)
     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 com.icorbroker.fx.client.screens.batchorder.BatchOrderFrame.<init>(BatchOrderFrame.java:217)
     at com.icorbroker.fx.client.screens.batchorder.BatchOrderViewController.createView(BatchOrderViewController.java:150)
     at com.icorbroker.fx.client.screens.RealTimeViewController.initialize(RealTimeViewController.java:23)
     at com.icorbroker.fx.client.screens.batchorder.BatchOrderViewController.<init>(BatchOrderViewController.java:62)
     at com.icorbroker.fx.client.screens.displayelements.DisplayPanel$3.mousePressed(DisplayPanel.java:267)
     at java.awt.Component.processMouseEvent(Component.java:5131)
     at java.awt.Component.processEvent(Component.java:4931)
     at java.awt.Container.processEvent(Container.java:1566)
     at java.awt.Component.dispatchEventImpl(Component.java:3639)
     at java.awt.Container.dispatchEventImpl(Container.java:1623)
     at java.awt.Component.dispatchEvent(Component.java:3480)
     at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:3450)
     at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3162)
     at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3095)
     at java.awt.Container.dispatchEventImpl(Container.java:1609)
     at java.awt.Window.dispatchEventImpl(Window.java:1590)
     at java.awt.Component.dispatchEvent(Component.java:3480)
     at java.awt.EventQueue.dispatchEvent(EventQueue.java:450)
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:197)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:144)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:136)
     at java.awt.EventDispatchThread.run(EventDispatchThread.java:99)

I've also been having the same problem. The only work-around seems to be to slightly change the code, recompile & hope it works. See http://forum.java.sun.com/thread.jsp?forum=38&thread=372291

Implement interface (with many variables)

If i have an interface that has 100 "public static final" variables and I access them by just "implementing" the interface in many other classes (so the variables are accessible via the variable name without any prefix), am I doing something wrong? The other approach of just accessing them thru the <class_name>.<variable_name> is the other option. Any insight, or is this a trivial difference and isn't worth worrying about? Thanks.

Any insight, or is this a trivial
difference and isn't worth worrying about? Thanks.Your solution is not considered proper because the class that inherits the constants will also expose them. So what should have been a private business is now a public matter.

Interfaces and implementation

My first lecture in "Programming Distributed Components" included this code listing:
import java.util.Date;
import java.util.Comparator;
import java.io.*;
public interface LogMessage
public Date getDate();
public String getMessage();
public String getSource();
public Comparator BY_DATE_DESC = new Comparator()
public int compare(Object o1, Object o2)
LogMessage lhs = (LogMessage) o1;
LogMessage rhs = (LogMessage) o2;
int dateCompare = rhs.getDate().compareTo(lhs.getDate());
if(dateCompare == 0)//in the event that dates are equal sort by message
{ //note - this is still a descending sort.
dateCompare = rhs.getMessage().compareTo(lhs.getMessage());
return dateCompare;
Call me stupid (please don't) but I was brought up to believe that java interfaces did not contain code implementation. Has the world gone mad or just my University lecturer? Or is it me? If the above code looks correct to you what is it that I am missing in my understanding of interfaces?
Thanks

I've not come across anything like this before. The
interfaces I have seen have tended to be rather simple
affairs consisting of simple contant declarations and
method signatures.They usually are. Your professor is getting fancy on you. Perhaps the point is to make you question what you think you know.
This opens up to me some other questions such as what
limitations are placed on the use of such objects? If
an object is a constant does that mean all its members
are constants? Why no use of "final" in this context -
is it already implicit in interfaces?There are no constants in Java per se. There are finals, which are variables that cannot be assigned once. A final primitve is effectively a constant and a final reference to an immutable Object (like a String) is effectively a constant (for our purposes.) All variables in interfaces are implicitly static and final.

Interface and Class

Hi pls any one can help me ?. In most of all the places we are declaring the constance in class files as
class A{
public static final String str_Constant;
After that we will refer this like "A.str_Constant"
Why we cant define it in interface like
interface A{
String str_Constant;
and refer like A.str_Constant
Thanks in advance

Not static either:The "static final" modifier is implied, since it doesn't make sense to have non-static, non-final variables in an interface. The way to go is to do this:
public interface Constants {
   public static final int SOME_CONSTANT = 0;
}This works if you have package-spanning consants (such as SwingConstants), but if you have class-specific constants you should gather them inside the class:
public class Stylesheet {
   public static final int BACKGROUND = 0;
   public void set(int arg, Object value) { ... }
myStylesheet.set(Stylesheet.BACKGROUND, Color.white);But this doesn't look very good (see enum's in 1.5), so it's probably better do solve it in some other way (depends on the project).
Regards,
Nille

Defining a FINAL Variable?

1. What is the advantage of defining a variable as final.?
For example:
In the System class,which is a final class,the static
field variable 'out' is final.
public final class System{
public static final PrintStream out;
2.Do we ever need to define a final variable ?
3.Can a class which is not final have a final variable?

This should not happenI've been tripped up by precisely this happeningon
occasion.I haven't, at least not as far as public finalstatic
variables are concerned.andyba,
I'm about to bet my right hand on the fact that you
are wrong. Just look at the compiled classfiles (in a
disassembler, or decompiler). The original class that
held the constant isn't referenced.
You can read more on this in this article:
http://www.javaworld.com/javaworld/javaqa/2003-03/02-qa
0328-constant.html
"According to the Java Language Specification, any
static final field initialized with an expression that
can be evaluated at compile time must be compiled to
byte code that "inlines" the field value. That is, no
dynamic link will be present inside class Main telling
it to obtain the value for A from InterfaceA at
runtime. "
/KajOk, I admit that the JLS enforces inlining of references to final static fields that are initialised by an expression that is evaluable at compile time means I was wrong on that count.
One reason why I am rarely, if ever, caught out by this is because I don't make regressive API changes, in this instance that means static final initialized field values do not change once they are fixed.
Note I did say that API changes of any nature do not "require" a recompilation, I said that it is recommended and therefore a sensible thing to do.
It is practically a golden rule in Software Development that once an API becomes public no
regressive/subtractive changes to that API should be made. This is one reason why the Java APIs are
becoming cluttered with deprecated annotations all over the place and why, to date, you rarely see
regressive/subtractive API changes in Java.
This rule has to be treated as "golden" simply because you will not always have the chance to recompile your code when deploying your application.
This can be especially problematic when deploying Remote or Web/EJB Applications to container platforms that are not known at development time.

Static and final modiers

Brief summary: I want to make the JButtons, JLabels, and JPanels public static final. Is that bad, and why? And what the heck is the Java system doing when it compiles and runs a program that does this? Is the code more efficient?
More questions below.....
I'm new to making GUI designs with Java. I am going to school and my teacher is making us do GUI interfaces in JAVA.
Early on, I learned that constants are identifiers similar to variables except that they holda particular value for the duration of their existence. QUESTION ONE: what happens during run-time, how does JAVA handle this constant?
I also learned that some methods may be invariant, as with a simple extension. These methods should be marked final. The subclass inherits both a madatory interface and a mandatory implementation. So I guess you use a final method when you want to model to a stric subtype relatinoship between two classes. All methods not marked final are fair game for re-implementation.
Well, that's good and well. So then I started thinking about static. That's a keyword in Java and when used with a variable, it's shared among all instances of a class. There is only one copy of a static variable for all objects of a class. So then again, I noticed that the programs in my book that used final usually threw in the word static before it. Memory space for a static variable is established when the class that contains it is referenced for the first time in a program.
Well, that too is great? Question 2: In my GUI programs, can I declare all the buttons (JButtons), labels (JLabels), panels (JPanels) as being final constant static?
In the program I don't intend to change the type of button, or JPanel so why not make it a constant? As long as I'm doing it, why not make it static? WHAT IS ACTUALLY GOING ON THEN IN MY PROGRAM WHEN I DO THIS?
Question 3: What goes on in JAVA when I make a method or function public static final. Is that what the Math class does? How is that handled during run-time? Is the code faster? Is it more efficient?
Question 4: If I make a class final, that means a subclass cannot extend it? Or does it mean that a subclasss cannot change it? I know that if the function or method in the parent class was final, then the subclass inherits both a madatory interface and a mandatory implementation....So if the class is final, then what?

Final makes a variable a constant. You can not change the variable once it has been initialized. A final method cannot be overridden in subclasses. So I would not make any button or menu item final unless you never want to change it. Final should be used to protect data. I don't believe there is a performance difference if they are used.
Static variables exsist only once. So if you have a class with a static variable and create several instances of that class the static variable will be the same in all of them.
Again data protection. Static variables are useful but a pain to use. I don't think there is a performance advantage with using them.

Static and final keyword questions

Brief summary: I want to make the JButtons, JLabels, and JPanels public static final. Is that bad, and why? And what the heck is the Java system doing when it compiles and runs a program that does this? Is the code more efficient?
More questions below.....
I'm new to making GUI designs with Java. I am going to school and my teacher is making us do GUI interfaces in JAVA.
Early on, I learned that constants are identifiers similar to variables except that they holda particular value for the duration of their existence. QUESTION ONE: what happens during run-time, how does JAVA handle this constant?
I also learned that some methods may be invariant, as with a simple extension. These methods should be marked final. The subclass inherits both a madatory interface and a mandatory implementation. So I guess you use a final method when you want to model to a stric subtype relatinoship between two classes. All methods not marked final are fair game for re-implementation.
Well, that's good and well. So then I started thinking about static. That's a keyword in Java and when used with a variable, it's shared among all instances of a class. There is only one copy of a static variable for all objects of a class. So then again, I noticed that the programs in my book that used final usually threw in the word static before it. Memory space for a static variable is established when the class that contains it is referenced for the first time in a program.
Well, that too is great? Question 2: In my GUI programs, can I declare all the buttons (JButtons), labels (JLabels), panels (JPanels) as being final constant static?
In the program I don't intend to change the type of button, or JPanel so why not make it a constant? As long as I'm doing it, why not make it static? WHAT IS ACTUALLY GOING ON THEN IN MY PROGRAM WHEN I DO THIS?
Question 3: What goes on in JAVA when I make a method or function public static final. Is that what the Math class does? How is that handled during run-time? Is the code faster? Is it more efficient?
Question 4: If I make a class final, that means a subclass cannot extend it? Or does it mean that a subclasss cannot change it? I know that if the function or method in the parent class was final, then the subclass inherits both a madatory interface and a mandatory implementation....So if the class is final, then what?

You have a lot of questions..
You make a method final if it should not be allowed for subclasses to override it.
If you make a class final, you will not be able to subclass that class.
A static method is a class method, i.e. you don't need to create an instance of the class to call the method.
You can make any object and primitive final, but for objects, you are still able to modify what is inside the object (if there is anything you can and are allowed to modify), you just can't change the final reference to point to another object.
When you make a variable final, you sometimes make them static as well if they should work like constants. Because there is no reason that every instance of the class has their own copy of constants.
If you make everything static, why even bother to work with object-oriented programming. It gives you no reason to make instances of your classes. You should try not to make static variables and methods when there is no need for it. Just because you start from a static main method, it doesn't mean it is necessary to make all variables and methods static.
Don't think so much about performance issues as long as you are still learning java. When you make a method final, it is possible for a compiler to inline that method from where you call the method, but you will hardly gain much in performance with that. In most cases it's better to optimize the code you have created yourself, e.g. look at the code you run inside loops and see if you can optimize that.

Interface and abstract class

why we have constructor for abstract class and not for interface,

When you call a constructor of a class which is extended by abstract class. It runs first the abstract class constructor and then child class constructor and initialize the member variables.
while interface has no variable all final data so interface is no need to implement a constructor.
Regards,

What is the diffrence between My Runnable Interface and Java Runnable

Hi folks
all we know that interfaces in java just a decleration for methods and variables.
so my Question is why when i create an interface its name is "Runnable" and i declared a method called "run" inside it.then when i implements this interface with any class don't do the thread operation but when i implement the java.lang.Runnable the thread is going fine.
so what is the diffrence between My Runnable Interface and Java Runnable?
thnx

Hi folks
all we know that interfaces in java just a decleration
for methods and variables.
so my Question is why when i create an interface its
name is "Runnable" and i declared a method called
"run" inside it.then when i implements this interface
with any class don't do the thread operation but when
i implement the java.lang.Runnable the thread is going
fine.
so what is the diffrence between My Runnable Interface
and Java Runnable?
thnxClasses and interfaces are not identified by just their "name", like Runnable. The actual "name" the compiler uses is java.lang.Runnable. So even if you duplicate the Runnable interface in your own package, it's not the same as far as the compiler is concerned, because it's in a different package.
Try importing both java.util.* and java.awt.* (which both have a class or interface named List), and then try to compile List myList = new ArrayList();

Trying to pass and object variable to a method

I have yet another question. I'm trying to display my output in succession using a next button. The button works and I get what I want using test results, however what I really want to do is pass it a variable instead of using a set number.
I want to be able to pass the object variables myProduct, myOfficeSupplies, and maxNumber to method actionPerformed so they can be in-turn passed to the displayResults method which is called in the actionPerformed method. Since there is no direct call to actionPerformed because it is called within one of the built in methods, I can't tell it to receive and pass those variables. Is there a way to do it without having to pass them through the built-in methods?
import javax.swing.JToolBar;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextArea;
import javax.swing.JScrollPane;
import javax.swing.JPanel;
import java.net.URL;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Panel extends JPanel implements ActionListener
     protected JTextArea myTextArea;
     protected String newline = "\n";
     static final private String FIRST = "first";
     static final private String PREVIOUS = "previous";
     static final private String NEXT = "next";
     public Panel( Product myProduct, OfficeSupplies myOfficeSupplies, int maxNumber )
             super(new BorderLayout());
          int counter = 0;
             //Create the toolbar.
             JToolBar myToolBar = new JToolBar( "Still draggable" );
             addButtons( myToolBar );
             //Create the text area used for output.
             myTextArea = new JTextArea( 450, 190 );
             myTextArea.setEditable( false );
             JScrollPane scrollPane = new JScrollPane( myTextArea );
             //Lay out the main panel.
             setPreferredSize(new Dimension( 450, 190 ));
             add( myToolBar, BorderLayout.PAGE_START );
             add( scrollPane, BorderLayout.CENTER );
          myTextArea.setText( packageData( myProduct, myOfficeSupplies, counter ) );
          setCounter( counter );
     } // End Constructor
     protected void addButtons( JToolBar myToolBar )
             JButton myButton = null;
             //first button
             myButton = makeNavigationButton( FIRST, "Display first record", "First" );
             myToolBar.add(myButton);
             //second button
             myButton = makeNavigationButton( PREVIOUS, "Display previous record", "Previous" );
             myToolBar.add(myButton);
             //third button
             myButton = makeNavigationButton( NEXT, "Display next record", "Next" );
             myToolBar.add(myButton);
     } //End method addButtons
     protected JButton makeNavigationButton( String actionCommand, String toolTipText, String altText )
             //Create and initialize the button.
             JButton myButton = new JButton();
                 myButton.setActionCommand( actionCommand );
             myButton.setToolTipText( toolTipText );
             myButton.addActionListener( this );
               myButton.setText( altText );
             return myButton;
     } // End makeNavigationButton method
         public void actionPerformed( ActionEvent e )
             String cmd = e.getActionCommand();
             // Handle each button.
          if (FIRST.equals(cmd))
          { // first button clicked
                      int counter = 0;
               setCounter( counter );
             else if (PREVIOUS.equals(cmd))
          { // second button clicked
               counter = getCounter();
                  if ( counter == 0 )
                    counter = 5; // 5 would be replaced with variable maxNumber
                    setCounter( counter );
               else
                    counter = getCounter() - 1;
                    setCounter( counter );
          else if (NEXT.equals(cmd))
          { // third button clicked
               counter = getCounter();
               if ( counter == 5 ) // 5 would be replaced with variable maxNumber
                    counter = 0;
                    setCounter( counter );
                  else
                    counter = getCounter() + 1;
                    setCounter( counter );
             displayResult( counter );
     } // End method actionPerformed
     private int counter;
     public void setCounter( int number ) // Declare setCounter method
          counter = number; // stores the counter
     } // End setCounter method
     public int getCounter() // Declares getCounter method
          return counter;
     } // End method getCounter
     protected void displayResult( int counter )
          //Test statement
//                 myTextArea.setText( String.format( "%d", counter ) );
          // How can I carry the myProduct and myOfficeSupplies variables into this method?
          myTextArea.setText( packageData( product, officeSupplies, counter ) );
             myTextArea.setCaretPosition(myTextArea.getDocument().getLength());
         } // End method displayResult
     * Create the GUI and show it. For thread safety,
     * this method should be invoked from the
     * event dispatch thread.
     public void createAndShowGUI( Product myProduct, OfficeSupplies myOfficeSupplies, int maxNumber )
             //Create and set up the window.
             JFrame frame = new JFrame("Products");
             frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
             //Add content to the window.
             frame.add(new Panel( myProduct, myOfficeSupplies, maxNumber ));
             //Display the window.
             frame.pack();
             frame.setVisible( true );
         } // End method createAndShowGUI
     public void displayData( Product myProduct, OfficeSupplies myOfficeSupplies, int maxNumber )
          JTextArea myTextArea = new JTextArea(); // textarea to display output
          JFrame JFrame = new JFrame( "Products" );
          // For loop to display data array in a single Window
          for ( int counter = 0; counter < maxNumber; counter++ ) // Loop for displaying each product
               myTextArea.append( packageData( myProduct, myOfficeSupplies, counter ) + "\n\n" );
               JFrame.add( myTextArea ); // add textarea to JFrame
          } // End For Loop
          JScrollPane scrollPane = new JScrollPane( myTextArea ); //Creates the JScrollPane
          JFrame.setPreferredSize(new Dimension(350, 170)); // Sets the pane size
          JFrame.add(scrollPane, BorderLayout.CENTER); // adds scrollpane to JFrame
          JFrame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE ); // Sets program to exit on close
          JFrame.setSize( 350, 170 ); // set frame size
          JFrame.setVisible( true ); // display frame
     } // End method displayData
     public String packageData( Product myProduct, OfficeSupplies myOfficeSupplies, int counter ) // Method for formatting output
          return String.format( "%s: %d\n%s: %s\n%s: %s\n%s: %s\n%s: $%.2f\n%s: $%.2f\n%s: $%.2f\n%s: $%.2f",
          "Product Number", myOfficeSupplies.getProductNumber( counter ),
          "Product Name", myOfficeSupplies.getProductName( counter ),
          "Product Brand",myProduct.getProductBrand( counter ),
          "Number of Units in stock", myOfficeSupplies.getNumberUnits( counter ),
          "Price per Unit", myOfficeSupplies.getUnitPrice( counter ),
          "Total Value of Item in Stock is", myOfficeSupplies.getProductValue( counter ),
          "Restock charge for this product is", myProduct.restockingFee( myOfficeSupplies.getProductValue( counter ) ),
          "Total Value of Inventory plus restocking fee", myOfficeSupplies.getProductValue( counter )+
               myProduct.restockingFee( myOfficeSupplies.getProductValue( counter ) ) );
     } // end method packageData
} //End Class Panel

multarnc wrote:
My instructor has not been very forthcoming with assistance to her students leaving us to figure it out on our own.Aren't they all the same! Makes one wonder why they are called instructors. <sarcasm/>
Of course it's highly likely that enough information was imparted for any sincere, reasonably intelligent student to actually figure it out, and learn the subject in the process.
And if everything were spoonfed, how would one grade the performance of the students? Have them recite from memory
public class HelloWorld left-brace
indent public static void main left-parenthesis String left-bracket right-bracket args right-parenthesis left-brace
And everywhere that Mary went
The lamb was sure to go
db

Open module for managing property file and environment variables

Looking for an open module for managing property files and environment variables (like CLASSPATH) set in a shell script. For handeling properties (preserving comments, supporting includes, appending new entries, and more) I have looked at SuperProperties from openadaptor but find certain functionality lacking. As for interfacing with common shell scripts/files containing setting for CLASSPATH, JAVA_HOME, other system/application variables another type of object editor is needed. Maybe JFIG?
Any ideas are greatly welcomed.

You seem wright, you hit a brick wall here with Air to find the location
of the command console on windows...
So in fact I never build an exe tool, but this little problem was a nice
case to test it and I tried it.:
I downloaded monodevelop
-GTK# for .NET 2.12.10*
-MonoDevelop 2.4.2*
from http://monodevelop.com/Download
created a console project and had an exe in 5 minutes !
You can download the findconsole tool and the projectfiles here:
http://greencollective.nl/temp/dump/findconsole_monoproject.zip
findconsole.exe will reveal the path/location of cmd.exe on a windows system.
Cheers,
Latcho

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