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Expression Language

Mike Firkser
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Joined: Oct 21, 2003
Posts: 247

Mr Bergsten,
I noticed your book has an appendix on EL - how in depth does the book go into EL?


Mike Firkser
Rutgers '84
Hans Bergsten
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Joined: Dec 01, 2003
Posts: 106
Originally posted by Mike Rutgers:
Mr Bergsten,
I noticed your book has an appendix on EL - how in depth does the book go into EL?

The appendix contains reference material: syntax, operators, literals, implicit variables and data type coercion rules; pretty much the same things you find in the JSP 2.0 specification, but hopefully in a more readable format.
The chapters contain less formal descriptions of these things, with plenty of concrete examples of how to use the EL in real applications.


Hans Bergsten, hans@gefionsoftware.com<br />Author of O'Reilly's<br />- JavaServer Pages,<br />- JavaServer Faces<br /><a href="http://www.hansbergsten.com/" target="_blank" rel="nofollow">http://www.hansbergsten.com/</a>
Nicholas Cheung
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Joined: Nov 07, 2003
Posts: 4982
Hi Hans,
How detail will be discussed in the appendix?
When I come across SCWCD 1.4 exam, many questions are related to EL. Some of them even give us one goal (for example): I want to print out the number 42, and then give us 6-7 options on EL.
I think many syntax of EL can archive the same goal, however, they are very similar and make me confuse. How deep the book discuss this issue?
Thanks.
Nick.


SCJP 1.2, OCP 9i DBA, SCWCD 1.3, SCJP 1.4 (SAI), SCJD 1.4, SCWCD 1.4 (Beta), ICED (IBM 287, IBM 484, IBM 486), SCMAD 1.0 (Beta), SCBCD 1.3, ICSD (IBM 288), ICDBA (IBM 700, IBM 701), SCDJWS, ICSD (IBM 348), OCP 10g DBA (Beta), SCJP 5.0 (Beta), SCJA 1.0 (Beta), MCP(70-270), SCBCD 5.0 (Beta), SCJP 6.0, SCEA for JEE5 (in progress)
Hans Bergsten
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Joined: Dec 01, 2003
Posts: 106
Originally posted by Nicholas Cheung:
Hi Hans,
How detail will be discussed in the appendix?
When I come across SCWCD 1.4 exam, many questions are related to EL. Some of them even give us one goal (for example): I want to print out the number 42, and then give us 6-7 options on EL.
I think many syntax of EL can archive the same goal, however, they are very similar and make me confuse. How deep the book discuss this issue?
Thanks.
Nick.


I'm afraid I can't give you a clear answer, but maybe someone else who has read the book and know about the SCWCD 1.4 exam can help you.
As I've stated earlier, I'm not a big fan of certifications in general, because they tend focus on details that are not so important to remember because you can look them up when you need them. To me, an understanding of the main concepts and how to apply them to solve a problem is much more important, so that's what I'm trying to teach in my books.
For instance, if you learn that an EL expression consists of variables and the operators found in most languages plus accessor operators for elements ("[]") and properties/keys ("."), and that you can access a bean property either as named element or as a property, I'm sure you can figure out which alternatives give you 42 as the result. All of these are valid:
${1 + 41}
${varContaining40 + 1}
${bean.propertyContaining42}
${bean[param.paramWithValue42]}
No offense; I know that some employers put a lot of value on certifications, but to me the Big Picture is much more important, because you need to understand the concepts in order to design applications that are easy to evolve and maintain, but you can always look up details such as syntax and coercion rules, operator precedence, or the parameter order for a method.
[ March 10, 2004: Message edited by: Hans Bergsten ]
 
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subject: Expression Language