Category Archives: Java/Java EE

Review: Marware Accent for iPhone 4

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Accent 4 After waiting two months for the Marware Accent Case for the iPhone 4, I was excited when it finally reach my doorstep. I prefer “flip” cases to shell cases for my smart phones since they protect the screen when placed in a pants pocket or a woman’s purse. On top of that, since they are often made out of leather, they provide a nice cushion should the phone be dropped from a few feet. Unfortunately, the Marware Accent 4 for the iPhone 4 suffers a serious defect with regard to the camera flash and was not worth the wait. Read on for the rest of the review.

The Good

Overall, the Accent 4 case design is quite nice. Unlike older iPhone 3 cases that most iPhone 4 owners have been using for the last 2 months, the Accent 4 fits the iPhone 4 perfectly. The mute button and power adapter are fully exposed. The speakers on the bottom are partially exposed with thin mesh netting over them. The volume buttons are cover by a thin sheet of leather with indentations for each button. Finally, the death grip area is completely covered so no need to purchase an iPhone 4 band aid.

The Bad

During the two month wait for the case, I called Marware support a few times, hoping to get a solid delivery date. It was scheduled to be sent out mid July but the Marware customer service representative informed me that there was a problem with the hole for the camera and flash being too small. They said it would be delayed another few weeks while they redesign it. I’m sorry to say, though, that they did not resolve the issue with the camera as the test below demonstrates:

I tried a number of different variations in light rooms, dark rooms, and pitch black rooms, but the results were all the same. As shown in the picture, some of the reflection was off the top of the hole so I tried readjusting the position of the iPhone inside the case but even without the direct bounce, there is always an awful glare/haze covering the picture. All of the pictures I took with the iPhone 4 inside the Accent case came out with a glare similar to the one seen above.

iPhone - Camera/Flash hole

Examining the back, the hole is large enough for the camera and flash to be seen without obstruction but not large enough for the flash to function properly. The flash functions by spreading light outward, and the width of the leather is too large so as to catch the light from the flash, and reflect it back into the lens.

Contacting Marware Support

Having ordered my case through Marware directly, I contacted Marware support about this defect. Despite the numerous revisions, Marware checked with the shipping manager and assured me that I did indeed have the finished product. Unfortunately, as the pictures above show, this product is still quite defective. I have to assume someone just said “close enough” and shipped the product as is. The support representative indicated Marware was not planning another revision at this time, although offered to refund my money. After waiting two months for a case, I’m reluctant to wait another two more.

Marware Support Followup

UPDATE: Marware’s official response on the Accent 4 flash defect:

Hello Scott,

As per our phone conversation today, the case you received is the most recent one. There are no plans for re adjusting the camera hole again at this point. The only suggestion provided to me is that when you use the flash, to push the iPhone up out of the case a little. If you are not comfortable doing that we can either exchange for another case or give you a refund.

I look forward to hearing back from you.

Regards,
Name omitted
Marware Customer Support Team

Despite acknowledging the issue, Marware does not seem to be interested in fixing it. At this time, I cannot recommend purchasing this case as it is clearly defective.

Creating a tar.gz file in Java

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Today’s article demonstrates how to create a tar.gz file in a single pass in Java. While there’s number of websites that provide instructions for creating a gzip or tar archive via Java, there aren’t any that will tell you how to make a tar.gz file without performing the same operations twice.

Reviewing Tar and Gzip Compression

First, download the Apache Commons Compression library. It is actually a subset of the code found in the Ant Jar for those performing compression operations that do not require all of Ant’s many features. Below is the code to create a tar and gzip archive, respectively, using the Compression library.

TarArchiveOutputStream out = null;
try {
     out = new TarArchiveOutputStream(
          new BufferedOutputStream(new FileOutputStream("myFile.tar")));
     // Add data to out and flush stream
     ...
} finally {
     if(out != null) out.close();
}
GZIPOutputStream out = null;
try {
     out = new GZIPOutputStream(
          new BufferedOutputStream(new FileOutputStream("myFile.tar")));
     // Add data to out and flush stream
     ...
} finally {
     if(out != null) out.close();
}

One subtlety in this example is that we use a BufferedOutputStream on the file stream for performance reasons. Often, archive files are large so that buffering the output is desirable. Another good practice is to always close your resources in a finally block after you are done with them.

The Solution

The solution is to wrap the tar stream around a gzip stream, since the order of writing goes inward from outer most to inner most stream. The code below first creates a tar archive, then compresses it inside a gzip stream. Buffering is applied and the result is written to disk.

TarArchiveOutputStream out = null;
try {
     out = new TarArchiveOutputStream(
          new GZIPOutputStream(
               new BufferedOutputStream(new FileOutputStream("myFile.tar.gz"))));
     // Add data to out and flush stream
     ...
} finally {
     if(out != null) out.close();
}

You can then treat the stream as a tar file using the TarArchiveEntry API to add entries and write data directly to the stream. The gzip compression will happen automatically as the stream is written.

jeanne’s SCEA 5 part 1 experiences

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Six weeks ago, I decided to take the SCEA 5 (Sun Certified Enterprise Architect) exam.  Today I passed part one with a score 87%.

(See part 2 and 3 notes as well)

Note: I did not pay for any mock exams.  I’m sure I would have scored above 90% had I done so.  I don’t think paying money for a higher passing score is worth it.  That isn’t learning for the sake of learning.  It is learning specifically for a test.

Since people at JavaRanch‘s SCEA forum often ask how one studied and about experiences, I decided to blog about it.

Deciding to take the test

The first thing I did was make sure the SCEA was not going away.  After all, who wants to be one of the last people to take the test before Oracle changes things?  As you can see in What’s next for Sun certifications now that Oracle is in charge? The SCEA looks quite stable and likely to continue.

While I’ve read the SCJP book, I’ve never taken the exam.  Multiple choice exams based on minutia that one doesn’t encounter in real life isn’t high on my list of things to do.  The SCEA doesn’t have the SCJP as a pre-requisite and emphasized the practical over trick questions and memorization so I decided to go for it.  Granted it is Sun’s view of the world so Spring and the like don’t fit it, but I find it a lot more relevant that the other exams.

My study plan

My plan was a wee bit vague.  I intended to get the study guide, see what was involved, study/practice as needed and register for the test.  I planned to spend 5-10 hours a week on this.  (I probably did this half the weeks.)  Here’s what actually happened:  [note this is a list of what I did and not what is good to do; see the next section for comments on the resources]

  1. Week 0
    • Decided want to take SCEA.  (My employer thinks it would be nice for people to get certified.  I’ve thought about doing so before, but this provided the final motivation to actually go for it.)
    • Convinced myself it is ok to do shortly before Oracle changes things because the SCEA looks intact.
  2. Week 1
    • Did sample questions to see where I stand.  (I copy/pasted the questions to notepad and removed the (*) next to the correct answers since they aren’t in a form one can use.  It still takes discipline to cheat, but I wanted it as a benchmark.  I got 5 or 6 out of 8 correct.  One of the answers was obviously incorrect.)  While this is (barely) above the passing score, I want to feel more confident before spending money to take the exam.  Decided if I read the SCEA book and practice some, I’ll be more reliably above it.
    • Ordered “Sun Certified Enterprise Architect for Java EE Study Guide“.
  3. Week 2
    • The only thing I did until the book came (Thursday) was look where the testing centers are me.
    • Once the book came, I read the first 5 chapters.  I was surprised by how easy the content was.  I guess this is because I already serve as an architect in some capacity.  This is good; I’ll be able to take Part 1 earlier than expected.
  4. Week 3
    • Registered for exam – since it doesn’t look overly difficult, I decided to take it soon.  I didn’t want to take in July 4th weekend and happened to have a day off work July 16th anyway, so I decided to go with July 16th.
    • Read remainder of book.
    • I had/was fighting off a cold part of the week so didn’t get much done.
    • The book contains sample questions that are supposed to be the level of difficultly of the exam.  (They seemed too easy, but turned out to be correct about the level of difficulty.)  Looked at scores to see how I am doing.  My scores for the chapters were 100%, 50%, 85%, 85%, 67%, 75%.  Some of the questions are not included in this percentage because I saw the answer before choosing one.  It was difficult to cover up the answers well.
  5. Week 4
    • Identified the areas I want to get stronger at:
      1. Make sure I can identify the design pattern names from descriptions.  While I am familiar with all the patterns, I often look them up in real life.
      2. Web Services – I know them in the capacity I have used them , but not as extensively as some of the other content.
    • Made flash cards for the design pattern names.  There are a few that have similar sounding descriptions and I wanted to make sure I could tell them apart.  After making the cards, it turned out I know almost all of them.  I imagine the act of making the cards did that.
  6. Week 5
    • Take free JavaBeat mock exams online to practice.  These were for the SCEA 4 exam, but interesting so I kept going.  Plus they gave me practice taking multiple choice closed book exams; a skill I haven’t used since college.
    • JavaBeat exams showed I need to review design patterns more didn’t do much this week though.  It was just too hot in New York City to think!
  7. Week 6
    • Reviewed the questions I got wrong so they are top of the mind
    • Looked at references from people in the SCEA forum at JavaRanch
    • Remind self not to read into questions (Sun doesn’t seem to think a web app is more secure than a fat client despite the logic being only on the server)
    • JavaChamp mock exam – got low score, but doesn’t tell how many correct answers there all the time so you have to guess how much to think about each question.
  8. The night before
  9. Take the test!

How were the resources I tried or read about?

Resource Cost Tried? Comments
Cade & Sheil Study Guide $40 Yes I relied on it heavily.  See my review on Amazon (which should be up within a day or two for more details.)
Whizlab Mock Trial free Yes 15 questions.  (got 93% on this which is slightly higher than real exam.  others have noted larger differences for Whizlab being easier.)  Satisfied with quality.
Whizlab Mock $100 No n/a – didn’t need extra help passing exam
Epractice Mock Trial free No I wanted to try this but you need a “free license key that gets e-mailed immediately” and it never came.
Epractice Mock $80 No n/a – didn’t need extra help passing exam
Sun’s epractice exam $65 No 120 SCEA 5 questions from Sun

n/a – didn’t need extra help passing exam
JavaBeat SCEA questions free Yes this is NOT for the SCEA 5 exam.  I found the design patterns and scenario questions to be good practice and comparable though.
About.com SCEA questions free Yes this is NOT for the SCEA 5 exam.  I found the design patterns and scenario questions to be good practice and comparable though.
JavaChamp Express Exam free Yes 20 question sample exam

Remember the SCEA 4 exam is quite different and study materials for it should only be used selectively.

What did I read?

Another thing people at JavaRanch typically state is what they read for the exam.  I really only read the Cade & Sheil study guide because so much of the content sounded familiar.  Prior to even thinking about taking the exam I have read many books including:

  1. EJB 3 in Action – see my review at JavaRanch from 2007
  2. Core Java Server Faces – see my review at JavaRanch from 2004
  3. JEE 5 tutorial – see my review at JavaRanch from 2006
  4. Other books further in the past including Gang of Four, Core J2EE Patterns, Design Patterns, etc

My impressions of the exam

  • I had a ton of time.  I completed pass #1 in 45 minutes.  I wrote down on paper which ones I wasn’t 100% sure of.  After pass 1, I calculated the total and I already had more 60% of the questions correct.  I then spent another 25 minutes on pass 2 thinking about the ones I wasn’t sure of or where more complicated.  Caveat: In school, I always finished tests with a load of extra time.  This just means the SCEA was consistent with other exams.
  • I dislike that you can’t review drag and drop questions.
  • Two of the questions I got wrong were because I didn’t realize they were in scope of the test – Java Cryptography Architecture and CORBA.
  • The questions were not tricky.  Subjective maybe, but not tricky.
  • I think this is one of those exams where having more experience hurts you a bit because you read into the questions.  For example, I know that a three tier app is more secure than a two tier app because you aren’t executing business logic on the client.  Sun disagrees.  I know because it is Cade’s book.  I imagine there are other things like that where the experience I have clashes with the test.
  • Most of the questions were high level.  There was only one I can recall that was at the level of what API/class name you would use and it was one every enterprise developer should know.
  • My section scores confirm these impressions.  I got 100% on web tier, applicability of JEE and Patterns.  I got 75% on Security (which would be the cryptography question), 66% on application design concepts and principles (which is only one wrong), 83% on integration and messaging (CORBA plus legitimate mistakes) and 87% on common architectures and business tier technologies (the two areas I suspect real world experience clashed.)

All in all, it was interesting and I felt the test was fair.