JSP Getting Started

[sukatoa]

I have a subject that covers JSP(new to me), accessing database through JSP(new to me), applets, UML(also new to me)

So, as im learning java, all i did to learn faster is i've created some applications(wi th sense). With my style of self learning, i hope it could be effective in JSP too....

I like to be advanced on the planned topic to be discussed by our instructor(He is not a certified Java Programmer though)

So now, all i know about JSP is the following:
-basic tags
expression <%= something%>
declaration <%! something%>
i dont know the term <% something %> I think it is an invocation
equivalent to java (Please correct me on that part)

-Setting up tomcat.
-The ROOT folder
-WEB-INF theoritically knew where to put classes/jars etc....
(though im not tested them yet)
-getting the value of a html form through request.getPara meter("form input-type name)

Those are basics obviously...( I learned them through surfing)

And im planning to create a simple application.
What comes on my mind is to reimplement my previous project (Simple Hotel FrontDesk System) into Online Hotel Reservation System
-the registration is obviously done by the hotel frontdesk only....
-Maybe the BlackList feature would be added if i knew the real ( Deep )

Actually, we have proposed a project "Online Entrance Exam" to our instructor and he likes it... so he approved our proposal.....( Not Thesis )

But before we start banging that project, deadline is on October ( Final week in this semester )

I like to grasp the essentials of JSP and also the other techniques, new way, and theory behind that architectural design for web application platform....
(Please correct me on the phrase above)

Actually, the faculty decided to order a J2EE book from Sun( i think the book base is in Singapore) for about 2500php or $56.00

Unfortunately, that book is expected to be arrived on midterms.... unbelievable scenario(but that was true)....

I did attempt to buy a new book instead of waiting that precious book, but i doubt for having such book....(for $40.99)....

So i decided to wait that precious book, yet learning in advance from this forum and the other web resources....

What a long story :)

Well, anyway,

Here is what i suppose to know in JSP as im building my experimental application for the supplement on my final project( Not thesis though )

I like to know about the JSP Beans,

for example, i have a java class that contains setter and getter methods,
i like to jar them, unfortunately, i didn't found the right tutorial for it on the web...

so can you post a helpful url that would teach me how to do that?
and also, about how to access the jar file from the jsp container( doubt of terms )Please correct me....

Or can you show an example?
For example, i have a jar file in WEB-INF/lib/JARZKY.jar
and the content is com\myclass.cla ss(with setSetter() and getGetter() methods)

How can you invoke that class through JSP?


A sincere Java Lover,
sukatoa

[r035198x]

I think by validations you mean form validations? I normally do it in the client side as well as in the server side(just to be doubly sure, and thats the way it should be :)). I dont see it as a disadvantage because those are the things a web developer should do, lets say what happens when a ignorant(or any user) turns the javaScript off in the browser? I as a web developer ensure that the user doesnt skip the mandatory things that he needs to fill. I dont think that it comes down to performance, its a securuty thing for me.

regards,

ajos

Yes, always do validations both client side and server side. It's one of the golden rules of web programming.

[JosAH]

Yes, always do validations both client side and server side. It's one of the golden rules of web programming.

Just a question: while I do understand that just client side validation would be
silly (no Javascript, request synthesis etc.) but what's wrong with just having
server side validation? (except for the server load).

kind regards,

Jos

ps. sorry for the hijack.

[r035198x]

If there's client side validations as well then the user doesn't have to wait for the page to be posted to the server just to be told that they left a field blank.

[JosAH]

If there's client side validations as well then the user doesn't have to wait for the page to be posted to the server just to be told that they left a field blank.

Ah, ok; so the reason for double sided validation is just speed. But then you have
to keep both validations in sync with each other. (just wondering)

kind regards,

Jos

[r035198x]

Ah, ok; so the reason for double sided validation is just speed. But then you have
to keep both validations in sync with each other. (just wondering)

kind regards,

Jos

Can become a nightmare right? Generally the server side validator must not assume any client side validators. So his job is easier. He doesn't need to sync with anyone. The client side validator only needs to do the best he can to make sure that the server code is not called unnccessarily.

[sukatoa]

Would you experts recommend me an article that discuss about creating effective javabeans or bugs of tomcat 5.5.x,

Im not sure about google's suggested...... .

I've encountered errors on getting the exact value from my bean........
If im gonna restart the tomcat, the errors gone, but when im going to add additional jsp code that filters the input, then the errors came back again.......

[sukatoa]

Would you experts recommend me an article that discuss about creating effective javabeans or bugs of tomcat 5.5.x,

Im not sure about google's suggested...... .

I've encountered errors on getting the exact value from my bean........
If im gonna restart the tomcat, the errors gone, but when im going to add additional jsp code that filters the input, then the errors came back again.......

That problem specifically, i've used an arraylist......

Base on my observation, when i used the class arraylist on my bean, a random interval will fail the updated value to be retrieved......

Is this problem already exists?

[sukatoa]

That problem specifically, i've used an arraylist......

Base on my observation, when i used the class arraylist on my bean, a random interval will fail the updated value to be retrieved......

Is this problem already exists?

I got it,

For me, there is a conflict when creating a bean that extends/contains an Object type ArrayList that will be used for storing some data that represents a String value.....

I don't know what's the real reason, but when i try to convert an Object type list into String type list

ArrayList<String> ret = new ArrayList<String>();
for(Object obj: ObjectList){
       ret.add((String)obj);
}
return ret;

The conflict occurs, in any time interval, the conversion fails........
Just for sure, i restarted the tomcat for the class files to be refreshed......

Hence, changing the type of the List into String resolves the issue........

[sukatoa]

This is my first time to have IF/ELSE statements more than i've expected on a single file..........

Is it natural to have more if/else statement on just a single JSP file?
or can you recommend to me experts how to reduce such structure? ( URL )

Looking forward on your replies,
sukatoa

[r035198x]

...

The conflict occurs, in any time interval, the conversion fails........
...

What was the exact error message?