Tag Archives: ocp

what does it mean to be OCP Java 8 Programmer II certified?

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There are now three paths for one to become OCP 8 (Java Programmer II certified.) So what does it mean someone certified had to know to pass the exam. Well, that varies too.

The three paths

  1. Starting out with Java 8 – take the OCP 8 (IZ0-809)
    Pre-req: OCA 8 (1Z0-808)
  2. Holding a Java 7 Professional cert – take the Java 7 to 8 upgrade exam (IZo-810)
    Pre-req: OCP 7 (IZ0-804) or Java 7 upgrade exam (IZo-805)
  3. Holding any Java 6 or older Professional cert – take the Java 6 or earlier to 8 upgrade exam (IZo-813)
    Pre-req: SCJP/OCJP 6 (IZO-851) or Java 6 upgrade (IZ0-852) or SCJP/OCJP 5 (IZo-853) or Java 5 upgrade (1Zo-854) or Java 4 or lower Professional cert

What one would expect

It seems reasonable to assume some things here.

  1. People taking the OCP 8 directly should be tested on the topics that entail being Java 8 certified.
  2. vennPeople taking the upgrade from Java 7 should be tested on just the topics that were added in Java 8. This is the purple in the Venn diagram. There’s no reason to retest on the topics that the were already on the Java 7 exam. That’s the overlap in the Venn diagram. (This is a bit simplified. It’s really that the topics should be those on the OCA 8 or OCP 8, but not on the OCA 7 or OCP 7. Luckily the topics added on the OCA 8 are also on the OCP 8.)
  3.  venn2People taking the upgrade from older versions of Java have a more interesting situation. When taking a very old exam, lots of topics are different. For example, new topics include generics and the enhanced for loop for those upgrading from Java 5. These topics are so old that it is reasonable to assume the candidate knows this as these syntax changes are covered as part of questions on all sorts of topics. Since the exam changed a lot between Java 6 and 7, let’s just imagine all upgrade candidates in this group took the Java 6 exam. Which would imply the topics covered should be the purple OCP 8 circle except for the overlap with the OCP 6 circle. It doesn’t imply the topics covered in OCP 7 but not OCP 6 or 8 should be covered. After all, those topics were removed from the OCP 8 exam so shouldn’t be needed to get a Java 8 certification.

These assumptions turn out to not match what Oracle actually did. The rest of this blog post describes the surprises.

What people starting out with Java 8 were tested on, but those upgrading from Java 7 were not

Topics:

  1. The concept of immutability
  2. The concepts of deadlock, starvation, livelock, and race conditions. They are tested when upgrading indirectly but with less emphasis.

My thoughts: No big deal here

What people starting out with Java 8 were tested on, but those upgrading from Java 6 were not

  1. The concept of immutability
  2. The singleton pattern
  3. The concepts of deadlock, starvation, livelock, and race conditions. They are tested when upgrading indirectly but with less emphasis.
  4. The entire topic of JDBC

My thoughts: Leaving out the first three isn’t a big deal. Leaving out JDBC is bizarre. That’s a whole topic that is part of core Java. It started being needed for Java 7 (or 8) certification. Upgrading from an older version seems like it should require it. But nope.

What people upgrading from Java 7 were tested on, but those starting out with Java 8 were not

  1. The computeIfAbsent() and computeIfPresent() methods on Map
  2. Also merge()  [removed from main exam in October 2015 and removed from upgrade exam in November 2015]

My thoughts: Odd to add topics on an upgrade exam. These are so similar, I’d almost think they were implied on the Java 8 exam.

What people upgrading from Java 6 were tested on, but those starting out with Java 8 were not

  1. The computeIfAbsent() and computeIfPresent() methods on Map
  2. Also merge()  [removed from main exam in October 2015]
  3. IO.2 – DirectoryWatcher, FileVisitor and WatchService
  4. Locks package in concurrency API
  5. DecimalFormat and SimpleDateFormat

My thoughts: This is bizarre. These three NIO.2 classes, the locks package and the two format classes were on the OCP 7 exam, but not on the OCP 8 exam. Oracle changing their mind and taking something off the exam for a later version is perfectly reasonable. However, I would think that would mean you don’t put it on the upgrade exam! Why should the upgrade exam cover something that isn’t on the target exam.

Summary

If I was writing the objectives for the upgrade exam from Java 6,  I’d have dropped some topics and added JDBC. But I’m not writing the exam objectives so will remain puzzled.

ocp java 8 programmer II beta

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Scott and I both took the OCP (Oracle Certified Professional) Java 8 Programmer II beta exam this week.

(edit: I’m now OCP certified with an 88%)

Logistics

We both had 106 questions. It was a three hour exam. I needed two hours for my first pass of the questions. I marked about 25 questions for review and used the remaining time for those. The nice thing about a beta is that you get lots of questions. Sometimes one question gives a clue for another question. For example (not on the exam), maybe you aren’t sure if a method is called set() or put(). Then you get to a question that uses put() and doesn’t have “does not compile” as a choice. Perfect. Now you know something.

As always, you can review questions you’ve marked or all questions in order. The only way to go to a specific question is if you’ve marked it for review. Otherwise you could potentially be clicking next scores of times. I tend to click a lot for review so this isn’t a problem.

Scott and I took the test at different testing centers. We were both given a locker for our personal belongings. I’ve been to a few testing centers and never seen that before. I like being able to have the key to the locker with my belongings!

We also both got one 8.5 x 11 erasable page with a felt tip erasable marker and an eraser. I like getting more than that. I found myself erasing a lot to make space. It’s really important to figure out how to make the best use of your space on the page. I use one column for questions I want to go back to and the topic (so I can look for answers hidden in other questions or think of it later.) I use another column for “facts.” They may be things I’m reminded of during the exam. Often there are things I write down the second the exam starts. That way I don’t have to keep it memorized. For the stuff that’s hard for me to remember. And I use the bottom for actually solving problems. Like drawing what is in variables.

The testing center I went to also gave me earplugs. First time I’ve ever been handed earplugs. The irony was that it wasn’t loud! When I went to the loud testing center, I didn’t get earplugs!

Study materials

For the new topics, see my blog post on the upgrade exam beta. There are a few new objectives in this beta that weren’t in the upgrade exam beta like @Override. Also, some objectives changed scope since the Java 7 exam. Which you can see from the objectives. But there’s nothing like taking the test to make that sink it. I reviewed largely from draft chapters of our upcoming OCP 8 book.

 

Objectives

 

why I like regular expressions + who says they aren’t readable

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Scott and I are working on our second book (OCP 8). I’m excited that I get to write the part about regular expressions as that is one of my favorite programming topics. Why, you ask? Because it lets you write clear and efficient code.

The scenario

For the book, I wrote an example showing how validating a simplified phone number is so much easier with a regular expression. The rules for the example were:

  1. a phone number is exactly 10 digits
  2. a phone number may contain dashes to separate the first three digits and next three digits, but not anywhere else
  3. no other characters are allowed (no parens around the area code in this example)

For example, 123-456-7890, 123-4567890 and 123456-7890 are valid. In real life, the third one wouldn’t be; we allow this typo here to be nice.  However dashes aren’t allowed in random positions. 12-45-67-890 is not a phone number.

Without regular expressions

This isn’t in the book, but i tired to write the code “the long way” to ensure it was annoying long. It was. I tried to write the code in a readable way and the best I could think of was:

private static boolean validateLong(String original) {
   String phone = original;
   // remove first dash (if present)
   if (phone.charAt(3) == '-') {
     phone = phone.substring(0, 3) + phone.substring(4);
   }
   // remove second dash (if present)
   if (phone.charAt(6) == '-') {
      phone = phone.substring(0, 6) + phone.substring(7);
   }

   // validate 10 characters left
   if (phone.length() != 10) {
      return false;
   }

   // validate only numbers left
   Set<Character> digits = new HashSet<>(Arrays.asList('0', '1', '2', '3', '4', '5', '6', '7', '8', '9'));
   for (int i = 0; i < phone.length(); i++) {
      if (!digits.contains(phone.charAt(i))) {
         return false;
      }
   }
   return true;
   }

This is a lot of code. And to those who think regular expressions are unreadable, what do you think of the above? I don’t find it easy to see what is going on even though I wrote it. There’s just too much logic and too much detail to ensure is correct. (And no, it didn’t work on my first attempt.)

With regular expressions

Re-writing to use regular expression gives me this:

private static boolean validate(String phone) {
   String threeDigits = "\\d{3}";
   String fourDigits = "\\d{4}";
   String optionalDash = "-?";
   String regEx = threeDigits + optionalDash + threeDigits + optionalDash + fourDigits;
   return phone.matches(regEx);
}

Even if you don’t know the regular expression syntax, it should be obvious what is going on here. We look for three digits, an optional dash, three more digits, another optional dash and a final four digits.

It’s a tiny bit longer in the book version because {3} isn’t on the exam so that part is:

String threeDigits = "\\d\\d\\d";
String fourDigits = "\\d\\d\\d\\d";

Still. Way easier to read and faster to write than the original code without regular expressions. I consider regular expressions like a hammer. They aren’t the right tool for every job, but they are quite helpful when they are the right tool.