Leonardo Crespo

Hi all. I passed SCBCD exam yesterday, with 92%. I took 35 days to prepare myself, studying every day for 2 hours. I pushed hard on weekends. I read Head First EJB twice, and i can assure that it's all you need to pass this test.

HF EJB is an impressive book. It's very well written, fun, cohesive and you can almost "feel" the authors trying hard to make you LEARN important topics. The authors surelly have a very good sense of humor. If they can make good jokes about cmr-fields, security roles, session beans and so on, you imagine what they can do with their everyday activities...

Wouldn't it be dreamy if you could buy a "Head First Oracle OCP" and a "Head First Stocks and Market Analysis" book? But it's probably just a fantasy...

Cheers,

Leonardo Crespo.

Thank you very much guys. Regards. Leonardo.

Hi all. Can you give me your opinion? I am studing for SCBCD. I already have HF EJB and i'm considering another book.

If i choose to buy Mastering EJB, should i buy the 2nd edition, which covers EJB 2.0 and was published in 2003, or the 3rd edition, which covers EJB 2.1 and was published in 2005?

Thank you.

Leonardo.

Greetings everyone.

I've being working on IT since 96, programming with Coldfusion, PHP, Java and Flash MX. I just passed SCJP5 and i'm wondering what to study next....

In your opinion, what is the most prestigious Java Certification one can get? I am assuming it is SCEA, but maybe there is another TOP certification from BEA, IBM etc.

Thank you for your comments.

Leonardo Crespo.

Hi all. I passed SCJP5 today, with 71%. It is a good score but i thought i could do better. Questions were not as hard as i expected.

Thanks to everyone for answering my questions and clearing all my dilemmas.

SCBCD, here we go!

Cheers,

Leonardo Crespo.
[ August 21, 2005: Message edited by: Leonardo Crespo ]

I'm a bit confused by those names, can anyone point to me what is the "Base Type" and the "Parameter Type" in the following code? Also, a definition for those terms would be very nice...

LinkedList<Float> floatList = new LinkedList<Float>( );

Tks

Leonardo.

Here the Reptile has nothing to do with your Reptile class!! The above declaration is just similar to:

public <R, S extends R> void listContent(List<R> myList, List<S> myOtherList)

Ooouch, i got it now. Thanks alot Prasanta!

Got it Prasanta, thank you for answering. I'll also make sure i always post the complete code.

Regards,

Prasanta, i see your point. Yes, your code worked just fine, thanks for answering.

I'm still wondering why my original code is not compiling... I posted the complete version, please let me know if you have any ideas.

Best Regards.

Here is the full code.


REPTILE CLASS
package generics; public class Reptile { public static void main(String[] args) { } public void walk() { System.out.println("reptile walking"); } }



SNAKE CLASS
package generics; import java.util.*; public class Snake extends Reptile { public void eatRat() { System.out.println("snake eating rat"); } public void walk() { System.out.println("snake crawling"); } }


GENERICS CLASS (tester class)
public class Generics { public static void main(String[] args) { Generics g = new Generics(); List<Reptile > listReptile = new ArrayList<Reptile>(); List<Snake> listSnake = new ArrayList<Snake>(); listReptile.add(new Snake()); listReptile.add(new Reptile()); listReptile.add(new Reptile()); listSnake.add(new Snake()); listSnake.add(new Snake()); listSnake.add(new Snake()); g.listContent(listReptile, listSnake); } public <Reptile, S extends Reptile> void listContent(List<Reptile> myList, List<S> myOtherList){ out.println("--------- printing myList ----------"); for(Reptile o : myList){ o.walk(); //////// THIS IS WHERE THE PROBLEM IS System.out.println(o.toString()); } out.println("--------- printing myOtherList ----------"); for(S o : myOtherList){ System.out.println(o.toString()); } } }
[ August 02, 2005: Message edited by: Leonardo Crespo ]

That should be the case, thank you Joyce.

I got 2 classes, Reptile and Snake. Reptile has the walk method and Snake overrides it.

I'm having a compile error with this code

for(Reptile o : myList){
o.walk(); //////// THIS IS WHERE THE PROBLEM IS

This is the compile error msg:
--------------
java:34: cannot find symbol
symbol : method walk()
location: class java.lang.Object
o.walk();
--------------

Why the compile still thinks o is an object, even when it says explicitly "Reptile o : mylist" ?

Thank you. Leonardo.


public class Generics { public static void main(String[] args) { Generics g = new Generics(); List<Reptile > listReptile = new ArrayList<Reptile>(); List<Snake> listSnake = new ArrayList<Snake>(); listReptile.add(new Snake()); listReptile.add(new Reptile()); listReptile.add(new Reptile()); listSnake.add(new Snake()); listSnake.add(new Snake()); listSnake.add(new Snake()); g.listContent(listReptile, listSnake); } public <Reptile, S extends Reptile> void listContent(List<Reptile> myList, List<S> myOtherList){ out.println("--------- printing myList ----------"); for(Reptile o : myList){ o.walk(); //////// THIS IS WHERE THE PROBLEM IS System.out.println(o.toString()); } out.println("--------- printing myOtherList ----------"); for(S o : myOtherList){ System.out.println(o.toString()); } } }

Hi, i'm playing with the code to better understand generics.

I tried to compile this:

List<? > listReptile = new ArrayList<Reptile>();

Which to me is saying "put an ArrayList<Reptile> in a list of unknown. However, i'm getting this compile error:

Snake.java:12: cannot find symbol symbol : method add(generics.Reptile) location: interface java.util.List<capture of ? extends generics.Reptile> listReptile.add(reptil);

I am particulary confused by the "capture of ? " message. Can anyone help me understand this error msg?

Thank you. Leonardo.

Hi, i could use some help on assertions

K&B book says that
java -ea: mypackage.mysubpackage MainClass

will enable assertions for all classes in mysubpackage and all classes in every subpackage bellow that.

J2SE5 DOC says that:
java -ea: mypackage.mysubpackage... MainClass

(note the 3 dots ... after mysubpackage). is the correct syntax for enabling assertions in mysubpackage classes and all classes bellow it.

Which one is the correct option? Both works for me...

Thank you very much.

True, thank you Barry!