JavaRanch Developer Certification (SCJD)

Is the Essay voucher transferable?

Tue, 13 May 2008 15:47:12 MDT

I have a voucher for the essay part expiring 6/30 and I haven't had time to finish my assignment. Was wondering if it is transferable, if so, does anyone want to buy it at a deep discount?

Not sure if I'm posting in the right area. Thanks!

Can I contain any CSS file for userguide.html

Tue, 13 May 2008 15:15:12 MDT

Hi:
I wonder if I can contain any CSS file or other files for userguide.html

Thanks

closing file from finalize() and explicitly calling finalize()

Tue, 13 May 2008 03:45:11 MDT

Hi all,

Iam closing a file from the body of the finalize() method and am not sure what will happen if an exception is thrown by the close() method.

The javadoc state the following (Iam not exactly sure what this means, I mean if the finalization is terminated, then the object is not garbage collected?):
If an uncaught exception is thrown by the finalize method, the exception is ignored and finalization of that object terminates.

Also thinking about explicitly calling the finalize method.

Does anyone know what the best practice guidelines are regarding these two things?

thanks in advance,

James

Please help me...!!!

Mon, 12 May 2008 23:43:10 MDT

Hi All,
This is sukilesh from India. Im planning to take SCJD. I got 94% in SCJP.
It will be helpful for me if any one gives me the guidelines to prepare for this certification. Im fully dependent on this forum because none of my friends have given SCJD yet. Please help me in this regard...!!!

Is there any limitation about the final jar file?

Mon, 12 May 2008 10:47:08 MDT

Hi:
I wonder if suncert website set any maximum file size for uploading our assignment?
cuz my user guide will probably contain a couple of snapshots.

Thanks

Lee

textbox field validation in gui

Mon, 12 May 2008 07:43:07 MDT

I have a query regarding how we can handle the situation whereby the user chooses an invalid db file , enters an invalid port number or tries to start the rmi server and leaving the database location and/or port field blank.

In my current design the user should enter these values in the Ui and click on the 'start' button in the gui to start the rmi server however just wondering how others have dealt with the sitation when the user enters invalid or no values for the database location field and/or port number. Do you display an error dialog to the user and allow him/her to re-enter these values in a seperate or the same window.

I would like to display a dialog message with the user message and then return to the origi...

How to submit the assignment

Mon, 12 May 2008 05:59:07 MDT

Please guys,

can someone help me with the url and procedure for submission of scjd

thanks

Odd behaviour of project in Windows Vista

Sun, 11 May 2008 05:25:04 MDT

Hi all,

I had tested my project well on my local machine(Windows XP) and it worked fine. I then tested the same code on my flat mates machine which was Windows Vista and kept getting a FileNotFound Exception which made no sense as the file was there and all the priveleges required eg. reade+write were provided.

Also I was not able to find the suncertify.properties file in the Windows Vista machine, But I definitely know its there somewhere as the fields are automatically populated with values previously entered. I have looked in the current working directory(where it should be) and also searched the entire C drive for it with no luck..

Anyone have any ideas if the above two problems may be caused due to W...

Does anyone buy Sun voucher recently?

Fri, 9 May 2008 22:21:00 MDT

Hi:
I want to buy a voucher for essay exam.
When I order it online, after entering every information, I press order
but nothing happened.
Then I go back to the original page, I found the link disappear.
I don't know if I have ordered the voucher successfully.
I can't check my order status.

Does anyone buy Sun voucher online recently?
Do I need to call a representative to buy the voucher?

Thanks

Passed 389/400

Fri, 9 May 2008 20:57:00 MDT

Finally, got the results after almost 4 weeks of waiting, here it is:

Assignmnet: URLyBird 1.2.1

General Con: 100 96
Documentation: 70 70
OOD: 30 30
GUI: 40 33 (I admit I cut a few corners here)
Locking: 80 80
Data Store: 40 40
Network Server: 40 40
Total: 400 389

Special thanks to specific ranchers who regularly answered my questions, and of course to everyone else whose past discussions turned out to be very very helpful.

As a final note to future/current candidates, this forum truly covers almost 100% of what you need to pass scjd.

About Java 2 Platform Production

Fri, 9 May 2008 09:14:58 MDT

Hi:
I am using JDK 1.6 Update 4 to develop my assignment.
I just wonder if this is a Java 2 Platform Production or just a Development.

Thanks a lot

Lee

Runing two alone mode applications?

Thu, 8 May 2008 14:34:56 MDT

Do you guys ever try runing two alone mode applications at the same time?
I found it's a big issue, cuz they belong to different VM.
A lof of objects designed to singleton will fail in this situation.

Is there anyone ever consider this case?
or examiner won't test like this.

Thanks

swing(gui) code - how to keep it organized?

Thu, 8 May 2008 13:04:56 MDT

Hi all,

I was wondering how you guys go about keeping swing code manageable.
I mean, my client-side gui contains long long lines of code for many components(menuBar, search fields, table, buttons, etc.) and most of the code is in the constructor. I have divided the code into different groups and commented them, but that's about it:
//menubar
code
//search panel
code
//table panel
code
..so on

Would this be neat enough? or should I put each group into different methods and call the methods one by one in the constructor(is this necessary, though?)?
How are you guys doing this?

Thanks

Jon

When can I download the assignment after the purchase

Thu, 8 May 2008 09:28:55 MDT

Hi,

I purchased the assignment yesterday by credit card. But I still cannot download it now. I have to wait 48 hours, right?

Besides, this assignment is $250, how about the essay, $150, or $300?

Thanks a lot!

checking for available records for booking

Wed, 7 May 2008 15:16:53 MDT

Hi

My assignment B&S says that a record can be booked when the owner field is empty.

where do we have to check whether the owner field is empty or not.

Currently I am checking this in the business method:
bookContractor

pseudocode
bookContractor(customer id, recordNumber) throws SecurityException{
1. if( record is already booked )throw SecurityException;
2. lock
3. read record
4. update
5. unlock
}

Or should we just check this at the GUI layer(client side) by getting the owner id from the TableModel and prevent the calling of business method bookContractor.

How did you approach this?

B&S: Doubts in RMI

Wed, 7 May 2008 12:18:53 MDT

Hi Ranchers,

Background
----------
I am working on my SCJD. Until now I've created a Data-Access-Layer and a GUI. Between both I've implemented a very small business layer (methods book, release, search). My GUI doesn't communicate directly with the Data-Access-Layer, it goes over the business layer. The application works quite fine, but until now it is all single-user. I've not create the server part.

I'm quite familiar with topics like Swing or the RandomAccessFile, but RMI and Sockets are new for me. Because I don't know any of these twos techniques, and most of you use RMI, I decided to make my first steps in RMI.

Server
------
I successfully created a very small test case with a ...

How many people among How many passes the SCJD ?

Wed, 7 May 2008 03:00:52 MDT

Hi All !
I just want to know that if 100 people sit for SCJD how many get it clear it ?

Wish me best

Wed, 7 May 2008 00:42:51 MDT

Hi Friends !
I am Awdhesh Kumar.
Done SCJP 1.5. And starting my preparation for SCJD.
Wish me best. I am excited after joining this forum.
Will get good friends here.

Help concerning the "isLocked" method

Tue, 6 May 2008 07:58:49 MDT

I have implemented the "isLocked" method in the following manner:

code:

boolean isLocked(int recNo) {
 mapLock.lock();
 try{
 return (lockedRecords.containsKey(recNo));
 }finally{
 mapLock.unlock();
 }
}

I was wondering how you guys decided to then use this method inside your bussiness logic. Did some of you just implement it and did not use it at all. Or can we use this method prior reading or finding data to enhance record locking on the client side?

Thanks for your responses.

Fred

Waiting dialog

Mon, 5 May 2008 13:04:47 MDT

Hi all at this forum,

I'm thinking of using a small waiting dialog for actions (specifically: user hits book button) which might take a long time, for example because they are waiting for a lock to get available, or for a lousy network connection.

But most of the time, creating and showing the dialog would take more time then the whole action to be finished, so probably this is overdoing and overcomplicating the assignment.

Just wondering how people are handling this:

1) do you have any waiting dialog or message for the user with actions which might take time? Or is just a simple mouse pointer change enough?

2) is it smart to disable action invoking components (buttons, menu's) ...

search-- action Performed:

Mon, 5 May 2008 12:34:47 MDT

Hi all,

Can some of you comment on my actionPerformed method for the SearchButton's actionListener.

What you think of the way I create the criteria string?
My business layer is on server side and it will return an ArrayList to
client and then a TableModel is populated and JTable is set. ? How about that?
This actionPerformed method can handle cases where
1. user search by name only
2. user search by location only
3. user search by name and location

I do not allow search of name Logical OR location, as it doesnt make much
sense to me.? what you think?

Thanks

Thanks

code:

 
public void actionPerformed...

gui choices

Mon, 5 May 2008 01:16:45 MDT

Hi all,

I'm doubting a bit about my GUI main window design.

I could go for the "natural reading order" design (going from left top to right bottom), meaning I have the search edits and search bottom on top, then a big panel with the table, and then at the bottom right the book button.

But this is not a "logical grouping of components", and it feels more natural to group all buttons / edits together on the bottom pane (search items left, book button right) and have the table fill the whole top/center area above it.

Any thoughts?

Rinke

Passed with 384/400 (B&S 2.3.2)

Fri, 2 May 2008 13:16:29 MDT

I passed today, 4 weeks to the day (almost to the minute) from when I completed the essay portion (uploaded Thursday, took essay Friday).

Here is the breakdown:
General Con: 100 93
Documentation: 70 70
OOD: 30 30
GUI 40 31
Locking: 80 80
Data Store: 40 40
Network Server: 40 40
Total: 400 384

I have no idea what I missed on GUI. I implemented:
"Administrator functions" add, delete and modify contractors (in addition to list, book, and unbook). To aid in use, buttons for administrator functions could be shown/hidden via a check box menu item
"starts with" v. "contains" search,
"case insensitive" search
search on any of the fields
get all records v. ref...

Do we need to filter the search result data?

Fri, 2 May 2008 08:14:28 MDT

I am confused on the instruction about search function.
Here is description in instruction:

UI:
It must allow the user to search the data for all records, or for records where the name and/or location fields exactly match values specified by the user.

DB:
Returns an array of record numbers that match the specified
criteria. Field n in the database file is described by
criteria[n]. A null value in criteria[n] matches any field
value. A non-null value in criteria[n] matches any field
value that begins with criteria[n]. (For example, "Fred"
matches "Fred" or "Freddy".)

Does this mean I need to filter the search result data?
For example, user enter "Fred: on UI,...

B&S:Populate the field information into the Record Object

Thu, 1 May 2008 01:42:24 MDT

Hi Guys,

I am using the VALUE OBJECT pattern which is mentioned in Andrew's book, but I am stuck with a question.

In the instruction of the assignment, in the header information part, it includes the DB schema as well, and all of the field names and length can be found here.
After I read every Record information, I need to populate all the field values into the OBJECT,in my Case, my Record Object is called Contract.And I will populate the information like this(similar to Andrew's book's example)
I will use the Length which grabbed from the header information part.
String name=fieldReader.readField(****,****);
String location=fieldReader.readField(****,****);
String spec=fieldReader.readField...

Is checking for SecurityException in updateRecord method required?

Wed, 30 Apr 2008 01:32:21 MDT

Hello Ranchers,

I am doing the URLyBird project. and I have a question on the SecurityException that is thrown by the updateRecord method.

The JavaDoc for updateRecord(long recNo, String[] data, long lockCookie) below suggests that the updateRecord() method should do a check on the LockManagers reservations (a hashmap object that stores the record number as the key and lockCookie as the value) against the parameters provided to the updateRecord() prior to committing the changes to the database.

// Modifies the fields of a record. The new value for field n
// appears in data[n]. Throws SecurityException
// if the record is locked with a cookie other than lockCookie.
public void updat...

Search Filter methods

Tue, 29 Apr 2008 07:54:18 MDT

(UrlyBird 1.1.1)

Most posts in this forum on the search function are on the interpretation of the "starting with" versus the "exact match" instructions. I will not repeat that, you can do a search if you want to read prior discussions on this.

My conclusion is:

Data returns matches starting with...
For the gui, these results are filtered back to only exact matches

What interests me now, is HOW to do this filtering. Just wondering how people are handling this. You can filter already on the server side or on the client side. And you can filter with an extra table model layer, or directly on the arraylist with rooms.

What is the most elegant sollution?

B&S: how to deal with the header information

Tue, 29 Apr 2008 01:36:18 MDT

Hi Guys,

Just want to know can I set the other header information as final static variables(coz tat will be much easier), or I should load it from the db file every time I need them.

i.e, the length of every field in a record,
the offSet of the Record 0..

things like this.

Hope that someone can help me

Thanks...

About the caculation for the offset

Mon, 28 Apr 2008 18:00:16 MDT

Hi Guys,
I got the B&S assignment, but after I read the offset from header information.
I tried to read the record from the DB file by this way: dataInStream.read(byteArray, offset,len), but I cannot get what I need here.

I know the offset is the 4 byte numeric value in the header, did I do the wrong thing to read the records?

Anyone can help me?Cheers

Passed SCJD

Mon, 28 Apr 2008 13:54:16 MDT

I like to thank all the people here who helped me. This forum is the best. Good luck all.

Test: Sun Certified Developer for the Java 2 Platform (310-027)
Score: 345
General Considerations (maximum = 100): 99
Documentation (maximum = 70): 70
O-O Design (maximum = 30): 30
GUI (maximum = 40): 31
Locking (maximum = 80): 44
Data store (maximum = 40): 40
Network server (maximum = 40): 40

URLyBird: Concurrent modification of records - How to deal with it?

Mon, 28 Apr 2008 11:36:16 MDT

Hi ranchers

i'm doing URLyBird (v. 1.1.3). Currently i'm having a hard time figuring out, how to implement the client's business logic. The assignment paper requires my UI ...
- "to allow the user to search for all the records, or for records where
the name and/or location fields exactly match values specified by the
user"
- "to allow the user to book a selected record, updating the database
ngly"

if there is 1 RAF instance, then why lock??

Mon, 28 Apr 2008 00:02:14 MDT

Hi all,

If your design consists of only 1 working RAF instance for the whole program(and all methods using this instance is synchronized), it means only one operation(read,write,etc.) can be done at a time. Then what's the point of having logical locking mechanism(lock(), isLocked(), etc.)? Just for the sake of meeting scjd specification? And is this really meeting the concurrency requirement in the spec, when nothing can be done concurrently?

I personally wanted to have 1 RAF instance per client, but I decided not to, since there are limitations on the number of file pointers that can exist at the same time. A pool of RAF instances can work(and I might implement one), but it seems to be complicating the problem.

B&S Writing to messages to console.

Sat, 26 Apr 2008 13:38:09 MDT

Hi All,

I have seen some people who passed the SCJD had mentioned that they just chose to write messages to console.

Is writing to console means nothing but using System.out.println("....")?

Is it neccessary to have this certification?

Sat, 26 Apr 2008 09:30:09 MDT

Hi everyone,

I have cleared SCJP 5.0 and I am willing to take SCWCD 5.0.
I want to know is it necessary to have this certification.

B&S Configuration?. Help me understand it.

Thu, 24 Apr 2008 08:58:02 MDT

Hello people,
This question has been asked many many times. Still some things are not clear to me by reading
the related threads.

Here are my questions

1) can i create a package suncertify.config. In that package i want to create a java class Called Configuration which is the entry point to my application

In the Configuration class, I have a main() method constructs a dialog for configuration based on the type of argument.

2)

java -jar <path_and_filename> Server

pops up a dialog that requires the following user input.

Server name: Is this really required? or can we get the Ip address using InetAddress.getLocalHos...

B&S-How to deal with some magic number?

Thu, 24 Apr 2008 08:20:02 MDT

How you guys deal with some magic number, like the index of data field?
For example, on UI portion, you have to know the index of owner field is 5
so you can set a customer ID when someone book a contractor, like
data[5] = "BS123456";

Do you hard code the index "5" or how you handle this?

Thanks

How you guys handle exception?

Wed, 23 Apr 2008 08:44:00 MDT

I have question about handle exception.
According to DB.java interface, we are limited to throw only several exception like RecordNotFoundException, SecurityException.
How about the IOException might be occured when accessing db file?
do you guys log into a text file or print it on console?
How do you handle these exception?

Thanks

Lee

Future Proof Design?

Wed, 23 Apr 2008 08:15:59 MDT

Hello,

I'm about to finish my assingment and I'm just wondering if anyone had take care of a future proof design.

The B&S Assignment says something of "Your user interface should be designed with the epectation of future functionality enhancements, and it should establish a framework that will support this with minimal disruption to the user when this occurs". Is this already done by using the model view control pattern or must I think a little bit deeper in this?

Another part of the assignment says "Bodgitt & Scarper wants to move into Internet-based marketing, and hopes to be able to provide their services directly to customers over the web." Have I to think about enterprise patterns, e.g. ValueList to...

the Essay exam

Wed, 23 Apr 2008 05:14:00 MDT

I am addressing to Those Who Passed:
I need some info about the technical details of the procedure:

Is the candidate allowed to use dictionaries (suppose my native language is not English)?
If yes, should the Candidate to bring the dictionaries with him, or them will be provided to him by Prometric employee?
Has the Application (the one the Candidate to interact with while the process) a spell-checker installed?
Does the Application allow to print the answers (in order to ensure that them look nice on paper)?

About choices.txt

Tue, 22 Apr 2008 15:01:46 MDT

I am at the point to work on documentation but I have no idea how much I am supposed to write in choices.txt.
I read some post on JavaRanch and found someone has below bulletin.
I just wonder if this is too much?
Why I need to talk about code clarity and documentation in choices.txt?
According to the insturction, choices.txt is

"Detail the problems you perceived, the issues surrounding them, your value judgments, and the decisions that you made. This document should also describe any uncertainties you had regarding the project, and the decisions you made when resolving them."

So I consider it's a document to describe your decision about design.
It's not a document to talk about the design co...

create() reusing possibly a deleted record

Tue, 22 Apr 2008 08:49:46 MDT

Hi All,

UrlyBird 1.3.1

In my server interface provided by Sun the specification says that the create() method should create a new record in the database with the possibility of reusing a deleted record. What exactly does this mean?

Deleted records are marked with a byte '1' so does this mean that if a record is marked as deleted in the file/database, i should create the new record by reusing the storage space on file taken up by a deleted record?

I would just like clarification on this issue and what the spec. means here.

Thanks,
David

Hard Code Magic Cookie?

Tue, 22 Apr 2008 07:59:46 MDT

I have taken a look several post on JavaRanch about magic cookie.
According to these discussion, the magic cookie is related to assignment version, also database schema version.
Can I say "Magic cookie is database schema number"?

So if I would like my application only to read a specific database schema,
I hard code the magic cookie in my code.

Is this a good way to deal with magic cookie?

Thanks

Some questions B&S...

Mon, 21 Apr 2008 18:04:21 MDT

Hi ranchers,

I�m starting the development of my project and I have a few questions:

1) The requirements for the GUI functionality in the B&S state that it must allow CSRs to search contractors and book a specific record. Now, is it necessary (for the purpose of the exam) to offer the CSRs a "Remove book" functionality as well?

2) In the Search part of my GUI, the user can search for all records or for records that exactly match values specified by the user regarding the name and/or location fields. Then, I�m thinking of putting two comboboxes, one containing the names of all contractors and one containing all the locations, and the user simply selects one or both of the comboboxes e clicks a search...

Exam Type

Mon, 21 Apr 2008 05:06:16 MDT

Hi,

What is the Exam Type? Heard that its not multiple choice as SCJP, SCWCD. Kindly, let me know the exam type and good study materials.

DataInputStream vs DataOutputStream

Mon, 21 Apr 2008 03:16:17 MDT

In my assignment, i am asked to use the format of DataInputStream and DataOutputStream. for reading, i can easily combine the readXxx() and
skip(long) methods to read values and reposition the file pointer respectively.

However, when it comes to writing, DataOutputStream has writeXxx() but these methods can only write to the end of the file. there is no method to reposition the file pointer in order to write to a desired position.

My question is, is there a way to reposition the file pointer for writing using DataOutputStream class?

I have 2 alternative approaches and i'll like some critique on my idea:

(1) I have thought of reading the entire database to memory and overwrite the databas...

locking - why do we have to identify the client?

Sun, 20 Apr 2008 12:20:12 MDT

hi all,

i was checking out the old posts to get an answer for the following question, but the answer isn't too clear to me.

question : (by David Winters Junior)
|why do we need to identify the client at all duirng locking?

answer : (by Alex Belisle Turcot)
|You need to know which client has the lock, to make sure that only this |client will be allowed to update/delete a record.. Which is the purpose of |locking the record.
|
|If you don't identify the client, then your update/delete got no way to |check if the "caller" is the "owner" of the record:
|1. Bob locks record 2.
|2. Alice tries to update record 2.
|3. Alice is not the client owning record 2, the operation is re...

Documentation/JavaDoc Question

Sun, 20 Apr 2008 00:36:26 MDT

My assignment paper is somewhat unclear about which functions are required to be documented in JavaDoc format. So far i used JavaDoc comments only for public and protected methods (the ones that could be of interest for external users). For private methods i used plain comments. How did you go about this?

Thanks,
alex

User interface Question

Sat, 19 Apr 2008 11:04:24 MDT

Hello,

my assignment paper for the SCJD says in the User interface section:

"Your user interface should be designed with the expectation of future
functionality enhancements, and it should establish a framework that will
support this with minimal disruption to the users when this occurs."

Can someone please explain, what this is supposed to tell me?

Thanks in advance,
alex

Record-level locking question

Sat, 19 Apr 2008 10:02:24 MDT

Sorry for the numerous questions. Internet access is sparse here in Iraq, so my posts tend to be "batch-posted" when I get online.

I'm implementing database record-locking. I have a Map<Long, Long> where key=recNo, and value=cookie. If there's an entry in the Map for that recNo, then the record is locked. When I use the wait() and notifyAll() methods, I'm using them on the map itself. I don't see how I can do it elegantly on a record-by-record basis.

My assignment specifies that if a client needs to lock a record, and the record is already locked, then the thread needs to go to sleep. In fact, it states that the thread must be "consuming no CPU cycles until the desired resource becomes available". By locking o...

Magic cookie in database file - what for?

Sat, 19 Apr 2008 09:58:24 MDT

So the database file provided in my SCJD assignment has its first two bytes reserved as a magic cookie at the very beginning of the file. What is this magic cookie for? I currently don't see a use for it. Am I missing something?