Newbie question: ""dynamic"" casting

Hello all,
 
I have a quite newbie question. I have this class hierarcy:
 
A
|_A1
|_A2
|_A3
|_A4
|_A5
|_.....
 
in some part of my code I have this:
 
if (object1 instanceof A){
if (object1 instanceof A1) {A1 object2 = (A1) e;}
 if (object1 instanceof A2) {A2 object2 = (A2) e;}
 if (object1 instanceof A3) {A3 object2 = (A3) e;}
 if (object1 instanceof A4) {A4 object2 = (A4) e;}
 if (object1 instanceof A5) {A5 object2 = (A5) e;}
object2.callMethod();
 
Is there any way to do this type of casting just in one line? I mean, I just want to cast object1 to the class it is instanceof. If it is instance of A1, I want to be casted to A1, if it is A2 to A2, etc...
 
Thanks you in advance.

kamikaze04 wrote:
In fact I know what object1 is on execution time,Which doesn't help your compiler at all, when it's task to link and verify method calls.
because the code posted at the top is working well, i just want to avoid repeating that if's for all the new classes Ax I will create. Big "code smell" here.
In other words if i had from A1 to A200 i dont want to have 200 if's to cast it to the class it is and then execute it's method.You could call the method "doMagic()" and make it abstract in A. Then you can implement it in all Ax classes and would never have to worry about casting in the first place, because A.doMagic() would automagically do the right thing. Polymorphism.

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Dynamic cast at runtime (Here we go again! )

Hy folks,
today I read so many entries about dynamic casting. But no one maps to my problem. For a lot of them individual alternatives were found. And so I hope...
Ok, what's my problem?
here simplified:
I have a HashMap with couples of SwingComponents and StringArray[3].
The SwingComponents are stored as Objects (they are all JComponents).
The StringArray comprised "the exact ClassName" (like "JButton" or "JPanel"),
"the method, who would be called" (like "addItemListener")
and "the ListenerName" (like "MouseMotionListener" or "ActionListener")
At compiletime I don't know, what JCommponent gets which Listener.
So a JPanel could add an ItemListener, another JPanel could add
a MouseListener and an ActionListener.
I get the description of the GUI not until runtime.
The 'instanceof'-resolution is not acceptable, because there are above 50 listener. If I write such a class, I would write weeks for it, and it will be enormous.
Now, my question
I get the class of the Listenertype by
Class c=Class.forName(stringArray[2]);
and the method I'll call
java.lang.reflect.Method method=component.getClass().getDeclaredMethod(s[1],classArrayOfTheParameter[]); //the parameter is not important here
And I have a class, who implements all required ListenerInterfaces: EHP
Now I wish something like this
method.invoke((JPanel)jcomponent,(c)EHP);
Is there anybode, who can give me an alternative resolution
without instanceof or switch-case ?
Greatings egosum

I see, your right. Thanks. This problem is been solved.
But a second problem is, that jcomponent can be every Swing-Object.
I get the swing-component as Object from the HashMap . And I know
what it is exactly by a String.
What I need here is
method.invoke(("SwingType")swingcomponentObject,Object[] args);
I know, that this doesn't exist. Here my next question
Can I take an other structure than HashMap, where the return value
is a safety type (and not an Object). Or there are some other hints
about similar problems and there resolutions?
I don't like to write 50 (or even more than 50) "instanceOf"-instructions or "equal"-queries. And I'm not really interested in the whole set of java swing elements existing.
I appreciate all the help I can get.
With regards egosum

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Greetings..this is a newbie question
We have 48 versions of JRE running in on XP IE6 in our company.
Some version beat up other JAVA applications.
It's a mess.
How can anyone manage this many versions?
Can we consolidate down to a few versions?
I saw some posts on changing the JRE dynamically or perhaps using a wrapper with a product from "sourceforge".
Are these viable?
Thanks in advance

We have 48 versions of JRE running in on XP IE6 in
our company.
Some version beat up other JAVA applications.
It's a mess.can you elaborate on how some versions "beat up" other apps?
How can anyone manage this many versions?you don't, each computer should periodically upgrade (IMO) but you shouldn't care. if you do, tell your users to load the latest version
Can we consolidate down to a few versions?sure
I saw some posts on changing the JRE dynamically or
perhaps using a wrapper with a product from
"sourceforge".
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Private inheritance and dynamic cast issue

Hello. I am hitting a problem combining private inheritance and dynamic casting, using Sun Studio 12 (Sun C++ 5.9 SunOS_sparc Patch 124863-01 2007/07/25):
I have three related classes. Let's call them:
Handle: The basic Handle class.
DspHandle. Handle implementation, able to add itself to a Receiver.
IODriver. Implemented in terms of DspHandle, It is the actually instantiated object.
Consider the following code. Sorry, but I've tried my best trying to minimize it:
#include <iostream>
using namespace std;
class Handle {
public:
virtual ~Handle() {};
class Receiver {
public:
void add(Handle &a);
class DspHandle : public Handle {
public:
virtual ~DspHandle() {};
void run(Receiver &recv);
class IODriver : private DspHandle {
public:
void start(Receiver &recv) {
DspHandle::run(recv);
void DspHandle::run(Receiver &recv) {
cout << "Calling Receiver::add(" << typeid(this).name() << ")" << endl;
recv.add(*this);
void Receiver::add(Handle &a) {
cout << "Called Receiver::add(" << typeid(&a).name() << ")" << endl;
DspHandle d = dynamic_cast<DspHandle>(&a);
cout << "a= " << &a << ", d=" << d << endl;
int main(int argc, char *argv[]) {
Receiver recv;
IODriver c;
c.start(recv);
Compiling and running this code with Sun Studio 12:
CC -o test test.cc
./test
Calling Receiver::add(DspHandle*)
Called Receiver::add(Handle*)
a= ffbffd54, d=0
The dynamic cast in Receiver::add, trying to downcast Handle to DspHandle, fails.
This same code works, for example with GNU g++ 4.1.3:
Calling Receiver::add(P9DspHandle)
Called Receiver::add(P6Handle)
a= 0xbfe9c898, d=0xbfe9c898
What is the reason of the dynamic_cast being rejected. Since the pointer is actually a DspHandle* , even when it is part of a private class, shouldn't it be downcastable to DspHandle? I think that perhaps the pointer should be rejected by Receiver::add(Handle &a) as it could be seen as a IODriver, that can't be converted to its private base. But since it's accepted, shouldn't the dynamic_cast work?
Changing the inheritance of IODriver to public instead of private avoids the error, but it's not an option in my design.
So, questions: Why is it failing? Any workarround?
Best wishes.
Manuel.

Thanks for your fast answer.
But could you please provide a deeper answer? I would like to know where do you think the problem is. Shouldn't the reference be accepted by Receiver:add, since it can only be seen as a Handle using its private base, or should the dynamic_cast work?
Aren't we actually trying to cast to a private base? However, casting to private bases directly uses to be rejected in compile time. Should the *this pointer passed from the DspHandle class to Receiver be considered a pure DspHandle or a IODriver?
Thanks a lot.

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Hi Nathan,
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Hope thats helpful.
Best,
David
Please rate any helpful posts.

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Hi,
I tried posting this in the LiveCycle Designer forum, but I think it's a bit too much of a newbie question:
Once in a blue moon when I'm at work, someone will ask me if I can add text fields to a PDF form so that they can easily type onto it and print it out. I've always done that directly in Acrobat (on the few occasions that it's been requested from me). But I was curious about Adobe LiveCycle since it came with CS3, so I played around with it a couple of days ago. I added the text fields in LiveCycle this time, and it seems to have worked fine. Which is the better program for this kind of task? I'm not 100% clear on the *main* purposes of either program or how they compare. If anyone wanted to give me a clue about it, I'd appreciate it!
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Phyllis

> I thought perhaps you could add that capability
You can (I said I was oversimplifying). However there are contractual
limits - to oversimplify (!) 500 users per form.
>Which would be preferable -- receiving form data from LiveCycle or Acrobat?
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>
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Aandi Inston

Total Newbie Question ... Sorry :-(

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Just a thought.

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Sorry for the newbie question... but it's been a long time since I have done this
Thanks!

Just define your site in DW as always. For a static site, that's all you need to do.

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Kimberly,
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Temporarily change the character format to not use that color.
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hello all (happy new year!),
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Method instanceMethod = getInstanceMethod(appToLoad);
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thanks!

point well taken. i've probably designed my application wrong if it's this difficult, but let me try to explain what it is i'm trying to do.
i had previously created a swing application whose central class (bootstrap initialized by a separate class with a main method) is a subclass of JFrame using the GridBagLayout manager. now, since more related gui applications are to be built, i thought it would be nice to build an application framework into which i could insert each standalone application into a JTabbedPane pane of the framework application.
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i've read a few things about implementing interfaces in order to get around the inability to cast types at runtime, but am not too sure of how that might work.
let me know if seeing some more of the code would help or if there's anything i should clarify.
thanks!

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Newbie question: ""dynamic"" casting

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