Declaring public static final variables in jsp?

The question is in the title...
I know this is not a jsp forum, but some people here might know if it's possible or not.
If yes, how to declare them and how to access them from other jsp pages?
Thx

If you need that, you definitely do too much work in your JSPs. You should do all your work in Servlets (or Actions if you're using Struts or something similar).
Your JSPs should only do the presentation.
Remember that JSPs are not classes (they are compiled into classes internally, but you don't have direct access to those).
If you absolutely need such a public static final field that you want to access from several JSPs, just define it in a Class and reference that class from your JSPs.

Similar Messages

ERROR: serializable class HelloComponent does not declare a static final

Hi everyone! I'm sorry but I'm a newbie to Java and I'm having some, I assume, basic problems learning to compile and run with javac. Here is my code:
import javax.swing.* ;
import java.awt.* ;
public class MyJava {
* @param args
public static void main(String[] args)
// TODO Auto-generated method stub
JFrame frame = new JFrame( "HelloJava" ) ;
HelloComponent hello = new HelloComponent() ;
frame.add( hello ) ;
frame.setSize( 300, 300 ) ;
frame.setVisible( true ) ;
class HelloComponent extends JComponent
public void paintComponent( Graphics g )
g.drawString( "Hello Java it's me!", 125, 95 ) ;
And here is the error:
1. WARNING in HelloJava.java
(at line 20)
class HelloComponent extends JComponent {
^^^^^^^^^^^^^^
The serializable class HelloComponent does not declare a static final serialVersionUID field of type long
ANY HELP WOULD BE GREAT! THANKS! =)

Every time I extend GameLoop, it gives me the warning
serializable class X does not declare a static final serialVersionUID field of type long
This is just a warning. You do not need to fix this because the class you are writing will never be serialized by the gaming engine. If you really want the warning to go away, add the code to your class:
static final long serialVersionUID=0;

Public static final Comparator String CASE_INSENSITIVE_ORDER

in this declaration..
public static final Comparator<String> CASE_INSENSITIVE_ORDER
what does <String> mean?
thanks!

what does the Comparator do. Look at the API and you would see the following description about the compare method.
public int compare(Object o1,
Object o2)Compares its two arguments for order. Returns a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.
The implementor must ensure that sgn(compare(x, y)) == -sgn(compare(y, x)) for all x and y. (This implies that compare(x, y) must throw an exception if and only if compare(y, x) throws an exception.)
The implementor must also ensure that the relation is transitive: ((compare(x, y)>0) && (compare(y, z)>0)) implies compare(x, z)>0.
Finally, the implementer must ensure that compare(x, y)==0 implies that sgn(compare(x, z))==sgn(compare(y, z)) for all z.
It is generally the case, but not strictly required that (compare(x, y)==0) == (x.equals(y)). Generally speaking, any comparator that violates this condition should clearly indicate this fact. The recommended language is "Note: this comparator imposes orderings that are inconsistent with equals."
Now your question is about what <String> is in your declaration. It is the type of the objects which are going to be compared.

Overloading a static final variable

This is a question from a book. I am not sure of overloading a constructor with a static final variable. Here is the class
public class Pizza{
private static final double cost_price = 10.0;
String topping;
double price;
}next, the question wanted me to create a constructor to override the topping and the price of the original constructor so i did
public Pizza(String t, double p){
topping = t;
price = p;
}Next it wants me to override the constructor another time only by receiving one parameter which is the topping by calling the above constructor but instantiate the price to the constant price which is the final static variable.
public Pizza(String t){
cost_price = p;
this(t, p);
}I dont know if the above solution that i did is correct as it maybe have some correction to be made because of the static final variable or the above code does not work. Please help me to verify thank you

Sorry but what does it means? Do you have any
solution? I would appreciate it .The last one should look like this:
public Pizza(String t){
this(t, cost_price);
}

Trying to acces the value of a public static final int using reflection

-Java 6
-Windows XP
-Signed Applet
doing the following:
Class.forName(classname).getField(code).getInt(null);
is giving me the error:
java.lang.IllegalAccessException: Class com.cc.applet.util.ServiceConfiguration can not access a member of class com.cc.util.error.codes.SendMessageErrorCodes with modifiers "public static final"
     at sun.reflect.Reflection.ensureMemberAccess(Unknown Source)
     at java.lang.reflect.Field.doSecurityCheck(Unknown Source)
     at java.lang.reflect.Field.getFieldAccessor(Unknown Source)
     at java.lang.reflect.Field.getInt(Unknown Source)
I'm not understanding why it can't access the value of the field. Any help would be great.
Edited by: zparticle on Oct 17, 2007 11:07 PM

stefan.schulz wrote:
oebert, you are right. Good one.
I actually think that, in this case, the message is misleading. The current implementation of sun.reflect.Reflection.ensureMemberAccess() treats any failing access check the same. It should and could inculde better contextual information.Stefan,
That is a good point. Did you file a RFE with Sun yet? I also think they should provide a more contextual error message in this case.
Gili

Constant values (public static final String) are not shown??

This has already been posted and no body answered. Any help is appreciated.
In web service is it possible to expose the Constants used in the application. Let say for my web service I need to pass value for Operation, possible values for this are (add, delete, update). Is it possible expose these constant values(add, delete, update) visible to client application accesssing the web service.
Server Side:
public static final String ADD = "ADDOPP";
public static final String DELETE = "DELETEOPP";
public static final String UPDATE = "UPDATEOPP";
client Side: mywebserviceport.setOperation( mywebservicePort.ADD );
thanks
vijay

Sure, you can use JAX-WS and enums.
For example on the server:
@WebService
public class echo {
public enum Status {RED, YELLOW, GREEN}
@WebMethod
public Status echoStatus(Status status) {
return status;
on the client you get.
@WebService(name = "Echo", wsdlLocation ="..." )
public interface Echo {
@WebMethod
public Status echoStatus(
@WebParam(name = "arg0", targetNamespace = "")
Status arg0);
@XmlEnum
public enum Status {
GREEN,
RED,
YELLOW;
public String value() {
return name();
public static Status fromValue(String v) {
return valueOf(v);
}

The serializable class SpacePainter does not declare a static final serial

The serializable class SpacePainter does not declare a static final serialVersionUID field of type longWhat does this mean??? It appears as a warning in Eclipse but I have no idea what it is. It happens when I create a class the extends JFrame or JCompnent or JApplet. I finnally got it to stop with this:
static final long serialVersionUID = 1;

Because your eclipse is configured that way. You can probably filter the warning. You don't have to implement the serialVersionUID, but you should if you really serialize the exceptions.

Help with public static final List

I'm having a block here... I want to have a constant List, but I can't figure out how to do it so it actually contains the values I want. It's going to be a list of strings about 40 elements long. Obviously, if I didn't need the final, I'd just do List.add( ), but I need to do it right in the constructor. Thanks for the help.

I guess the problem could be reworded, If I wantedto
put this in a class that would never getinstantiated
how would I initialize the List?You use a static intializer.Ah. I didn't get that out of the question. Thanks for the help.
But here's an example:public class Foo {
    static final java.util.List<String> list = new java.util.ArrayList<String>();
        list.add("one");
        list.add("two");
        list.add("three");
        // etc.
}

Static/Final variable

When progressing through a series of tests for simple adding/subtracting I find that my variables which I want to remain constant are changing, despite if i set them to static or final. The addition method adds variable 'a' to 'b', the second test adds variable 'a' to 'd'. Instead of adding 'a' to 'd' it is adding 'a+b' to 'd'. How can I set these variables so they are constant each time they are called?
        BigInt a = new BigInt(123456789);
        BigInt b = new BigInt(1234);
        BigInt c = new BigInt(-123456789);
        BigInt d = new BigInt(-1234);
        System.out.println("Case 1:" + a + " + " + b + " = " + a.add(b));
        System.out.println("Case 2:" + a + " + " + d + " = " + a.add(d));

"static" means that an attribute is a class attribute, shared among all instances.
"final" means for attributes that its value (either primitive or the reference) cannot be changed - it does not mean that the object it refers to is immutable.
You can't set them constant - but look how String handles things, it doesn't modify the String itself, but returns a new instance with the desired values. Let add() return a BigInt instead of modifying the instance it's called on.

Staticblock of static final variables

I have a class with
Static block
Which has dao call.
So when this class is called for first time static block is called .
Now suppose I return instance of this class from my session bean to a servlet.
Will this servlet also call static block ?

If the class has been created and the static initializer called then it won't be called again.

Will declaring primitives as static final (constants) conserve memory?

I wrote a code
int a = flag?1:0;on which my supervisor commented that 1 and 0 should be replaced by SomeInterface.ONE (=1) and SomeInterface.ZERO (=0) respectively. The reason he gave was that since constants are static so it will conserve memory.
Is this really true?

First of all, this Interface for Constants anti-pattern is widely derided.
Secondly, one of the reasons it was used in the first place was readability, not performance, and in that case constants that pertain to the meaning of that 1 and 0, and not the values, might have been understandable (e.g. SomeInterface.TRUE = 1 and SomeInterface.FALSE = 0), but definately not ONE and ZERO.
Thirdly, memory use is the same as public static final variables (as interface constants are), have their value compiled directly into the class using them, at the point where it used, so whether a constant is used, or a literal value, the space that that class definition uses is the same. In addition, there is then an interface definition that also has those values so the memory use is more, in end effect. And, regardless, that memory space is not on the heap, which is the memory space you will be most interested in, so it has no noticeable effect on memory space either way.

Static final in (Class or Interface)

Hello Friends ,
What is the difference in having a public static final variable in an class and having the same kind of
declarations in an Interface ?
Does the interface is better or having it in a class ?
Thanks in Advance,
-S

shyamnambiar wrote:
But I'm not clear . you mean to say its all the same .It does not make any difference ?The only difference that it makes (and that might be an important difference) is what you communicate with your design an intention.
Constants should usually be placed within their context since that's where they are going to be used, and that's where developers will look. It's more common to place the constants in the class that they are related to. They should not be placed in an empty final class just because you want to group constants. You should also avoid placing constants in an interface just because you then can implement that interface to "get hold of" the constants.
Kaj

Where can I declare a final variable?

I'm wondering where excatly I can declare a final variable. I know I can declare them right after I start the class.
i.e.:
public class x {
     public static final Scanner CONSOLE = new Scanner(System.in);
     public static final Random GENERATOR = new Random();
}I would like to declare a final within the main method. i.e.:
     public static void main(String[] args) {
          System.out.print("Please type in your name and press return: ");
          final String NAME = CONSOLE.next();
     }Is this just not possible or am I just writing it wrong? Couldn't find an example using google. Any help?
fyi: I'm fairly new to using java so this may be obvious.

     public static void main(String[] args) {
System.out.print("Please type in your name and
nd press return: ");
          final String NAME = CONSOLE.next();
     }Is this just not possible or am I just writing it
wrong?No, you can declare a local variable final, which means that it's value can only be set once in or after the declaration. But be aware that a new variable is created each time the method is invoked.
About the only reason people do this is so it can be used in a local class declared further down the method.

Serializable class doesn�t declare static final serialVersion of type long

The serializable class SomeClassName does not declare a static final serialVersionUID field of type long
I have a lot of these warnings in my current application.
What does it really mean?
In what situations do I actually want/need to use this?
If I need it somehwere, do I just declare this field?

Putting a version number on a serializable class is a precaution against the class definition changing in a way that confuses ObjectStreams when reading old serialisations.
You can just declare the varialble, initially make it 1 and crank it up in your source when you change the fields of the class.

Static Final Long Results in RMIC Failure

I have a variable in my remote interface:
public static final Long ID = new Long("0");Which causes an RMIC failure with the following error:
ID is not a valid primitive or String constant.So my question is, why must a static final variable be a primitive or a String?
Thanks,
toby

I couldn't reproduce your case maybe you could post more info. Here is what I did: I created a remote interface with a Long declaration like your's. I created an implementation of that remote interface and compiled and rmic'ed them with noe errors, here are the source files:
package junk;
import java.rmi.*;
public interface RIntf extends Remote {
    public static final Long ID = new Long("O");
    public String hello() throws RemoteException;
package junk;
import java.rmi.*;
import java.rmi.server.*;
public class RImpl extends UnicastRemoteObject implements RIntf {
    public RImpl() throws RemoteException {
    public String hello() throws RemoteException {
     System.err.println("junk");
     return "junk";
}After javac'ing these two source files I ran rmic on junk.RImpl to produce the stubs and skeletons without any issue. Let me know if this is similar to your issue. By the way, there is an RMI specific forum located here: http://forum.java.sun.com/forum.jsp?forum=58

Declaring public static final variables in jsp?

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