Niels Krijger

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since Apr 22, 2012
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Recent posts by Niels Krijger

Rajdeep Biswas wrote:The best way to deal with GC problems is to draw memory locations and doing it thoroughly, as a trick might yield wrong results.

With hindsight Rajdeep's answer is much better, I'd have fallen into quite a few traps with my solution. One I have actually fallen into is a GC-resurrection question.

Paul Anilprem wrote:
...But you are right, it could be a bit frustrating or even a distraction if there are too many of them. So we have removed most of them from the Last Day Test. It has only 5 of them now (reduced from 22).

thanks again,

Thanks Paul for the reply. The final test was particulary off-putting, the recent changes have made it much better! Thank you.
I'm planning to buy the Enthuware question set for the SCWCD examination; there really isn't a competitor out there that comes close. Keep up the good work!

i want to know is k&b sufficient for clearing ocpjp ?

More than sufficiently I'd say. I read it once thoroughly and it was the best contributor to my certification by far. Do take every sentency in it seriously though. And I don't know about the differences between OCPJP 6 and OCPJP 7... Check which exam you're taking and look at the exam's objectives.

and is there any difference in xams taken by sun and oracle ? pattern and qstn types are same or diff ??

First, Sun is now part of Oracle. If you're talking about Sun or Oracle you're talking about the same company really.
To answer the question; the question style in K&B is similar but more difficult than the exam's. There's more logic involved in K&B -which I actually enjoyed a lot- but you won't see much of this in the exam. Most of my OCPJP exam questions were max 15 lines of code and reasonably formatted (unlike K&B). Don't be put off by low K&B scoring; you're doing fine if you're above 50% or so.

Congratulation dude.. it's a very good score....

Not here to brag, but thanks :-). Please note I got much lower scores in my preparation which was the point I was trying to make.
Got my certification today and have to say, it looks quite nice! (better than my university's master degree weirdly)

// Note: I should have mentioned I'm working for a contractor for Oracle which may have biased my opinion (I don't see how, but it can ;-), consider this a legal notice).

[edit]I just noticed everyone is referring to me as "Neil" rather than "Niel" or "Niels". Don't mind but how come? Is Neil more natural in the tiny non-Dutch world out there? =]
9 years ago
Just passed OCPJP with 95% which was much higher than I had expected based on my preparation (I'll explain in a minute). I used these forums as a guide on how to prepare for my exam and like to return something by outlining my preparation path.

Materials: The two preparation exams offered by Oracle which you can buy at +/- 50 euros I think. I had the SCPJ6 Study Guide by Sierra & Bates, and used the Enthuware mock exam tool. I had 2 weeks (11 work days) in which I prepared for +/- 8 hours a day. Apart from the weekends there were no gaps between those workdays. On the 12th day I had the exam.

My background consisted of a University java course from 5 years ago (which included threading and GC; I remembered most of it which was a great help) but had little practical Java experience.

day 1: First mock exam from Oracle, scored 49% (with hindsight this was rather good). I actually believed I'd pass it at the first go, a bit naive ofcourse. The exam is genuinly not easy. I started GooGling the web for exam-info.
day 2: Reading here and there on the web (= NOT a good approach for preparation). Found Sierra & Bates book is highly recommended for this exam so ordered it online.
day 3: Bought Enthuware mock exam tool which offers plenty of questions. First test was 67% with cheating.
day 4: Did two more Enthuware mock exams, 73% and 70%, both with some cheating as well.
day 5: Did Enthuware mock exam, 65%, no cheating this time. Got the SCPJ6 Study Guide from Sierra & Bates and started reading.
day 6: Enthuware exam, 68%, no cheating. Further reading & practice exams from book.
day 7: Enthuware exam, 72%, no cheating. Further reading & practice exams from book.
day 8: Reading & practice exams from book.
day 9: Reading & practice exams from book. I generally had +/- 50-60% of the practice questions in Sierra & Bates correct. I fell in all the easy traps which was demoralizing. The logic of the correct answer hardly ever suprised me.
day 10: Did the two master exams included with the book. First one scored something like 74%, the other just 48%! (I blame it on a lack of coffee)
day 11: Did final enthuware exam, 75% (bit dissapointing), did second Oracle mock exam, got 85%.
day 12: in the morning tried to relax (and failed miserably). During the afternoon had the exam. Exam software is quite straightforward. Scored 95%.

As you can see nowhere during my preparation I got anything near to 95%. I found it very easy after all the preparation, the questions I did miss were API-related I found out later.

I made the stupid mistake of changing a question just before I submitted it; go with your first instinct if you dont know! If you review all the questions like I did assume your main logic was initially correct and check if you missed stupid stuff (like an "else if" without the "if" or attempts at illegal access), found 2 errors this way. If the question is particularly easy there's bound to be some trap somewhere.

I didn't write much code during this process, +/- 50 times I ran something and often only a few lines of code just to check if it would compile. Roughly 20 of those had to do with Primitive Wrappers (I actually had a nightmare about them!).
I used an IDE; you don't get the javac/java command prompt experience this way which I considered largely irrelevant for my future work. The SCJP book showed me enough to answer the basic questions on compiler javac/java.

With hindsight I consider myself over-prepared and would have done the following (assuming you have some sort of java experience, this is for you):
- First read SCPJ6 Study Guide by Sierra & Bates from cover to cover and do the practice questions.
- Do practice exams from SCP6 study guide for a second time and check which parts hurt the most. For me it were Primitive Wrappers, File IO and Generics.
- Write code to test your own assumptions on the difficult areas. Google a bit (check these forums!), check the Java API.
- Do master exams from the book, if you score > 50% I would claim you can try (the exam is a lot easier), with > 60% you're good to go.
- If you're not yet at those levels, do mock exams until you feel confident.
- The Oracle mock exams were the most realistic in terms of difficulty and question style, if you don't mind the cost I'd recommend them.

I personally had no troubly going through the SCJP6 book all at once (roughly 200 pages a day), the practice questions from the book kept it interesting. It does require discipline.
I'm unsure if I'd use Enthuware again, it contains Drag & Drop questions, a question style no longer part of the exam. If you don't mind those I'd recommend enthuware.

The master exams from SCJP6 book are a lot more difficult than the real thing. Yes it prepares you very well for the exam but I found it demoralizing as well. Don't do them all at once and only when you're in a good mood!

9 years ago
A method that worked for me (very quickly) was number each object and for each line write down the set of active references. If you do this you get the following:


Finally count the objects that dissapeared from the last line;

Total; 3

You can check by the count of the keyword 'new' whether you've written them all down (yep, I went up to 8 and count eight times 'new').