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Starting a Java Project with Maven – Step by step Guide for Mac

djitz — Thu, 05 Jan 2012 22:11:35 +0000

Thanks to my friend, Gandos, he got me interested to use Maven after I read his blog post (It’s in Indonesian). After consulting to another friend, I think it’s a good idea to use Maven for the LabGence project.

The idea is also influenced from this question that I have, “What is the best practice to upload an open-source project?” and “What files that I should and probably shouldn’t upload?”.

I believe Maven can standardize the issue of libraries needed by the project, and also the build script needed. So I decided to give it a try.

Fortunately I found the best and brief introduction tutorial to Maven on JavaBrains.org, you might want to check it out.

I also created the following step by step notes for Mac OSX (which might be applicable also to Linux and other Unix OS).

Maven Installation
Steps:
1. Download Maven binary from the official website. I use the Maven 3.0.3 as of this writing.

2. Extract the compressed files.

3. Execute these commands:
# export M2_HOME=[path to the Maven extracted directory] example: # export M2_HOME=/home/djitz/dev/java/maven

# export PATH=[path to the Maven extracted directory]/bin:${PATH} example: # export PATH=/home/djitz/dev/java/maven/bin:${PATH}

4. Test the maven installation, execute:
# mvn --v
If it shows something like:

Apache Maven 3.0.2 (r1056850; 2011-01-08 19:58:10-0500) Java version: 1.6.0_24, vendor: Apple Inc. Java home: /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home Default locale: en_US, platform encoding: MacRoman OS name: "mac os x", version: "10.6.5", arch: "x86_64", family: "mac"

then we’re done for the installation.

Creating Project
Steps:
1. Go to the directory where we want to have the project.

2. Execute
# mvn archetype:generate
It will download files because it’s the first time we’re running it.

3. After it finished the download, it will ask for number, and show us the default number. Scroll up and we can see hundreds of different project templates that Maven knows.

For now, just press Enter to accept the default one.

4. Choose the Maven archetype quickstart version, just press Enter to accept the default.

5. For the groupId, input your package name.
example: com.djitz.labgence

6. For the artifactId, input your application name.
example: LabGence

7. Type the version, just press Enter to accept the default.

8. Type the package name, it will copy the value from step #5.

9. Confirm the values from step 5 – 8.

That’s it, we successfully created a new project using Maven.

Some more commands to try, go to the created project directory, then do the following commands:

# mvn compile # mvn package

There are a lot more functions of Maven, but this can get us started. Sonatype.com does a lot of work with Maven, and they have a free Maven reference book in here. (http://www.sonatype.com/books/mvnref-book/reference/index.html
)

Until the next post fellas!

Write JavaDoc in an Instant (Part 1) – Templates for Methods

djitz — Mon, 28 Nov 2011 03:46:42 +0000

We all love good and commented codes, but most of us either don’t know how to write a good comment for our codes, or just plain lazy to write one.

In Java, JavaDoc is pretty much the industry standard when it comes to auto-generated code tool. And as a strong believer of good software development practice, I always put comments on my code.

To save time, I created this template for methods so I can always refresh myself about how to write a good JavaDoc for my code. These codes are taken from the Java SDK source codes, so talk about how the creator of the Java write their comments (no one can be more expert than them I suppose).

*The template below is a slide presentation in Google Docs, to see the code expand its view to full screen, or you can download it as PDF or PPTX.

How to Install Eclipse ADT, Android SDK, and setup AVD Emulator

djitz — Sun, 20 Nov 2011 17:05:06 +0000

The Android Honeycomb

A couple of weeks ago I was so fortunate to get the opportunity working with the Android SDK development in my job (Samsung Galaxy Tab 10.1 ).

Compared with Android mobile app development using the Adobe Flex 4.5, the Android SDK may be a bit more tricky to do, so to document my experience I created this blog post (and maybe some more posts in the future).

To start developing Android apps, we need to install the Eclipse ADT, Android SDK (obviously..), and setup the AVD.

ADT – Android Development Tools
AVD – Android Virtual Device

Prerequisite:
- Familiar with Eclipse IDE

Steps:

1. Get Eclipse (I use Eclipse 3.7 – Indigo), download from:

Eclipse.org or EclipseSource (cloud download – a lot faster!!! )

2. Get Android SDK, run the installation:

After the installation, run the SDK Manager

Check “Tools” and the Android version you’re going to develop.

3. Install the Eclipse ADT (Android Development Tools) Plugin:

Run Eclipse

Click Help > Install New Software

Click Add, copy the following to the Location input: https://dl-ssl.google.com/android/eclipse/

Check “Developer Tools” and follow the rest of installation wizard.

4. After restarting the Eclipse, check if the ADT picks-up the SDK directory correctly:

Run Eclipse

Click Windows > Preferences

Click Android on the left sidebar.

5. Create the emulator:

Run the Eclipse.

Go to Window > AVD Manager.

Click “New” button.

Fill the fields:

Name: em31
Target: Android 3.1 – API Level 12
SD Card size: 64 MB
Snapshot: enabled
Hardware:
Device ram size: 768

click “Create AVD”.

The new AVD should appear in the AVD Manager, click “Start” button to run it.

*It takes time to start the AVD, in my machine it takes 7 mins.

FAQ

Q: Why the AVD is so sloooooooww in my computer?

A: There’s nothing wrong with your computer, it’s really the problem with the AVD. If you followed my steps correctly, we should’ve set the RAM size to 768MB and enabled the snapshot. Enabling the snapshot means that whenever we run the emulator, it will bypass the longer boot process. Set the option save to snapshot on the first time, but un-check it whenever we run the emulator afterward, because saving to snapshot will take significant time as well. :p

How to Load Test Flex Application Using JMeter

djitz — Tue, 30 Aug 2011 03:27:00 +0000

Two weeks ago I got responsibility to load test the web application of the company where I work using JMeter.

It’s not the first time I heard about JMeter, because about two years ago I was involved in a large project that demands high availability and high number of concurrent users at the same time (talk about more than 3,000 branches nationwide).

However, it was my friend who was assigned to explore the capabilities of JMeter back then. I’m not sure how far he went with the load testing, and what was the problem with JMeter, but we end up utilizing IBM Rational Performance Tester.

Unlike testing normal web application (that most likely involves HTTP standard requests such GET, POST, PUT, and DELETE), Flex application may use it’s BlazeDS web messaging to connect to the back-end server, this means it involves passing AMF binary files in the process.

Fortunately, JMeter has the ‘Recording Test’ capability to the rescue and simplify our life!

The idea is to create a proxy server that will run in the middle of the browser and the application server. This way the JMeter will record all the HTTP requests and files passed to the application server, and also their result. Sweeet!

So how to do that? Just follow the steps below:

Steps:

Setup the Thread Group
1. Run JMeter
2. Right click on Test Plan > Add > Threads (Users) > Thread Group
3. Rename the Thread Group to ‘Load Test 1′
4. Set the Number of Threads (Users) field to the number of load test user simulation you want (i.e: set to 25).
5. Right click on ‘Load Test 1′ > Add > Listener > Aggregate Graph
6. Repeat step 5, this time choose Aggregate Report
7. Repeat step 5, this time choose Summary Report
8. Repeat step 5, this time choose View Results Tree

Setup the HTTP Proxy Server
1.Right click on WorkBench > Add > Non-Test Elements > HTTP Proxy Server
2. Set the port to available open port in your PC (i.e.: set to 8989)
3. Check ‘Redirect Automatically’
4. Type ‘ .* ‘ in the include field.
5. Set Target Controller to Test Plan > Load Test 1
6. Click Start to start the Proxy Server

Setup the Browser
1. Run the browser, and set the connection properties to use proxy.
2. Set it to localhost and the port you set above.
3. Browse the Flex application and try to use it as usual.
4. The JMeter should capture the HTTP request operations you made to the server.
5. Press Stop on the HTTP Proxy Server to stop the recording.

Do the Load Test
1. Now we have the example of HTTP request operations, click the Load Test 1 Test Plan.
2. Press Ctrl+R to run the load test, you should see the green indicator on the top right that it’s running the tests.
3. Check the Test Results in all four Listeners you added earlier.

This steps were proven working in my case and I use Apache JMeter 2.4 r961953. If they don’t then try to put some comments below. Happy load testing!

Texas Drivers License Driving / Road Test Success Guide (Detailed)

djitz — Fri, 01 Jul 2011 03:53:07 +0000

Congratulations, you have passed the Texas drivers license written test and now you are going to take the driving test, or also called road test.

So, are you nervous about it? Well, I was nervous for several days before I took the road test. But don’t worry, I will give you the guide how to pass the driving test successfully.

What is tested in the road test?

#1. The Car

Interestingly enough, the first thing that the examiner will test is whether the car is working properly or not. She will ask you to do the following:

Show the car inspection and registration sticker
Show the car insurance card
Turn the left and right signal lights
Test the horn
Press the brake to test the brake lamp

Tips:

Make sure you have all the valid car inspection, registration, and insurance.
Check the signal lights, horn, and brake lamp prior to taking the road test.

#2. Parallel Parking

After the examiner felt safe to ride with the car, she will sit in the front passenger’s seat and ask you to drive to the parallel parking spot located inside the DPS parking area.

I find it hard to describe how the parallel parking spot looks like by word, so let me draw it rather:

What you need to do is straight forward, parallel park your car on the spot shown and don’t hit the pole. If you hit the pole you failed the parallel parking test, and that also means you failed the road test.

Tips:

Practice well your parallel parking skills prior to taking the road test. Although in Texas there is very little chance you need to do parallel park your car (due to the huge spaces everywhere), the purpose of the examiner need to test your parallel parking skill is to make sure you know how to control your car.
If you have no clue about how to parallel parking, watch the parallel parking tutorial videos on my YouTube playlist.
If you don’t always have the car to practice with, use these simulation games:

#3. The Road Test

Alright, after you passed the parallel parking test successfully, the examiner will then ask you to drive outside of the DPS parking lot and go to the road. The area around DPS is usually a pretty empty traffic neighborhood, but with lots of intersections (The DPS where I took the test have 5-6 intersections).

The examiner will tell you when to turn left, right, or go straight. For the driving test it takes around 15-20 minutes.

Tips:

Practice enough for few days prior to the road test.
Don’t be nervous, remember all what you have practiced.
STOP COMPLETELY on the introduction with stop sign, rolling stop is not enough.
Observe the speed limits.
Do left and right turn correctly.

#4. The Final Result

The examiner will tell you to go back to the DPS and park your car. She will then tell you where are your mistakes, if there is any, and tell you some comments. Finally, she will tell you whether you pass or fail (let’s think positively, you pass).

If you pass, the examiner will ask you to go inside the DPS office with her and wait till they print the temporary drivers license for you.

If you fail, she will give the paper to you and ask you to schedule another appointment for the road test.

Closing

Alright, that’s the detail about the drivers license road test in Texas. I wish you good luck guys and hope you pass the road test.

Texas Driver License Test Questions and Answers Part 2 (Review)

djitz — Mon, 27 Jun 2011 02:56:09 +0000

Texas Driver License Test Questions and Answers 2 (Review)

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Practice yourself before taking the Texas Driver License written test! Start Congratulations - you have completed Texas Driver License Test Questions and Answers 2 (Review). You scored %%SCORE%% out of %%TOTAL%%. Your performance has been rated as %%RATING%%
Your answers are highlighted below.

Question 1

What does the sign above mean?

	Another road enters the road you are traveling on from the direction shown. Watch for traffic from that direction.
	Crossroad ahead. Slow down, look carefully in all directions.
	Pedestrian Crossing. You are near an area where a large number of pedestrians cross the street. Slow down and watch for people crossing the street on foot.
	Warns of a traffic control signal ahead.

Question 2

What does the sign above mean?

	Gives advance notice of a reduction in the number of lanes of pavement ahead.
	Another road enters the road you are traveling on from the direction shown. Watch for traffic from that direction.
	The pavement ahead narrows; reduce speed. Room for two cars to pass, but with caution.
	Indicates traffic is permitted to pass on either side of a traffic island or an obstruction.

Question 3

What does the sign above mean?

	The road curves one way (right) and then the other way (left). Slow down, keep right and do not pass.
	Road ahead makes a gradual curve in the direction of the arrow (right). Slow down, keep right and do not pass.
	There is a winding road ahead. Drive slowly and carefully and do not pass.
	Road ahead makes a sharp turn in the direction of the arrow (right). Slow down, keep right and do not pass.

Question 4

What does the sign above mean?

	You are approaching a point where other traffic lanes come together with the one you are on. Watch for traffic from that direction.
	You are approaching a point where two roadways come together, but you are not required to merge, an additional lane begins. Watch for traffic in the new lane.
	The divided highway on which you are traveling ends ahead.
	You should drive in the right-hand lane and expect oncoming traffic in the left-hand lane.

Question 5

What does the sign above mean?

	Slow down on wet road. Do not suddenly turn, speed up, or stop.
	The divided highway on which you are traveling ends ahead.
	There is a winding road ahead. Drive slowly and carefully and do not pass.
	Road ahead makes a sharp turn in the direction of the arrow (right). Slow down, keep right and do not pass.

Question 6

What does the sign above mean?

	You are near a school. Slow down, and prepare to stop suddenly if necessary. Watch for children.
	Slow your speed and watch for persons who may be disabled or who may be crossing the roadway in a wheelchair.
	Be prepared for a stop sign ahead.
	Pedestrian Crossing. You are near an area where a large number of pedestrians cross the street. Slow down and watch for people cross- ing the street on foot.

Question 7

What does the sign above mean?

	You are near a school. Slow down, and prepare to stop suddenly if necessary. Watch for children.
	Slow your speed and watch for persons who may be disabled or who may be crossing the roadway in a wheelchair.
	Be prepared for a stop sign ahead.
	Pedestrian Crossing. You are near an area where a large number of pedestrians cross the street. Slow down and watch for people cross- ing the street on foot.

Question 8

What does the sign above mean?

	Indicates traffic is permitted to pass on either side of a traffic island or an obstruction.
	You are approaching a point where other traffic lanes come together with the one you are on.
	Gives advance notice of a reduction in the number of lanes of pavement ahead.
	Watch for traffic in the new lane.

Question 9

What does the sign above mean?

	Indicates traffic is permitted to pass on either side of a traffic island or an obstruction.
	You are approaching a point where other traffic lanes come together with the one you are on.
	Gives advance notice of a reduction in the number of lanes of pavement ahead.
	Watch for traffic in the new lane.

Question 10

What does the sign above mean?

	The pavement ahead narrows; reduce speed. Room for two cars to pass, but with caution.
	The bridge ahead is not as wide as the road. Slow down and use caution.
	The hard-surfaced pavement changes to an earth road or low- type surface. Slow down.
	There is a significant drop from the pavement edge to the shoulder.

Once you are finished, click the button below. Any items you have not completed will be marked incorrect. Get Results

There are 10 questions to complete.

List

Return Shaded items are complete.

1	2	3	4	5
6	7	8	9	10
End

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Texas Driver License Written Test Review Questions Part 1

djitz — Fri, 24 Jun 2011 01:51:40 +0000

Practice yourself before taking the Texas Driver License written test!

Texas Driver License Test Review Questions 1

Practice yourself before taking the Texas Driver License written test! Start Congratulations - you have completed Texas Driver License Test Review Questions 1. You scored %%SCORE%% out of %%TOTAL%%. Your performance has been rated as %%RATING%%
Your answers are highlighted below.

Question 1

What does the sign above mean?

	You must bring you car to a complete stop. Slowing down is not enough.
	You should slow down or stop if necessary so that you can yield the right-of-way to vehicles on the other road.
	Warns of a traffic control signal ahead.
	Crossroad ahead. Slow down, look care- fully in all directions.

Question 2

What does the sign above mean?

	You must bring you car to a complete stop. Slowing down is not enough.
	You should slow down or stop if necessary so that you can yield the right-of-way to vehicles on the other road.
	Warns of a traffic control signal ahead.
	Crossroad ahead. Slow down, look care- fully in all directions.

Question 3

What does the sign above mean?

	You must bring you car to a complete stop. Slowing down is not enough.
	You should slow down or stop if necessary so that you can yield the right-of-way to vehicles on the other road.
	Crossroad ahead. Slow down, look care- fully in all directions.
	Warns of a traffic control signal ahead.

Question 4

What does the sign above mean?

	Warns of a traffic control signal ahead.
	The divided highway on which you are traveling ends ahead. Be careful as you approach the point where two-way traffic begins again.
	Height of underpass from road surface is shown. Do not try to enter if your load is higher than the figure shown on the sign.
	Slow down on wet road. Do not suddenly turn, speed up, or stop.

Question 5

What does the sign above mean?

	There is a winding road ahead. Drive slowly and carefully and do not pass.
	You should drive in the right-hand lane and expect oncoming traffic in the left-hand lane.
	The road curves one way (right) and then the other way (left). Slow down, keep right and do not pass.
	Slow down on wet road. Do not suddenly turn, speed up, or stop.

Question 6

What does the sign above mean?

	The divided highway on which you are traveling ends ahead. Be careful as you approach the point where two-way traffic begins again.
	You should drive in the right-hand lane and expect oncoming traffic in the left-hand lane.
	You are approaching a point where other traffic lanes come together with the one you are on. Watch for traffic from that direction.
	Advises that you are approaching a section of highway where the opposing flows of traffic are separated by a median island.

Question 7

What does the sign above mean?

	Road ahead makes a sharp turn in the direction of the arrow (right). Slow down, keep right and do not pass.
	Another road enters the road you are traveling on from the direction shown. Watch for traffic from that direction.
	You should drive in the right-hand lane and expect oncoming traffic in the left-hand lane.
	You are approaching a point where two roadways come together, but you are not required to merge, an additional lane begins. Watch for traffic in the new lane.

Question 8

What does the sign above mean?

	Another road enters the road you are traveling on from the direction shown. Watch for traffic from that direction.
	You are approaching a point where two roadways come together, but you are not required to merge, an additional lane begins. Watch for traffic in the new lane.
	You are approaching a point where other traffic lanes come together with the one you are on. Watch for traffic from that direction.
	The pavement ahead narrows; reduce speed. Room for two cars to pass, but with caution.

Question 9

What does the sign above mean?

	The road curves one way (right) and then the other way (left). Slow down, keep right and do not pass.
	Road ahead makes a gradual curve in the direction of the arrow (right). Slow down, keep right and do not pass.
	Crossroad ahead. Slow down, look care- fully in all directions.
	Another road enters the road you are traveling on from the direction shown. Watch for traffic from that direction.

Question 10

What does the sign above mean?

	There is a winding road ahead. Drive slowly and carefully and do not pass.
	You should drive in the right-hand lane and expect oncoming traffic in the left-hand lane.
	Road ahead makes a sharp turn in the direction of the arrow (right). Slow down, keep right and do not pass.
	Road ahead makes a gradual curve in the direction of the arrow (right). Slow down, keep right and do not pass.

Once you are finished, click the button below. Any items you have not completed will be marked incorrect. Get Results

There are 10 questions to complete.

List

Return Shaded items are complete.

1	2	3	4	5
6	7	8	9	10
End

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Texas Driver License Test (Written and Road Test) Guide

djitz — Wed, 08 Jun 2011 16:43:43 +0000

Yup, just got my Texas Driver License this week after practicing to drive here in US for two weeks. Getting the Driver License in Texas is not that hard but don’t take it for granted too, you must make sure you give some effort to read the Texas Driver License Handbook and practice a lot driving in the road.

So what does it take to have a Texas drivers license?

0. The Documents

In general, this is the list of things you need to apply for driver license in Texas.

For you who are curious about how to get Texas driver license for foreign student, here’s what you need when you are applying:

Passport
I-20
I-94
School acceptance letter
Internship job acceptance letter (if internship)

Just make sure you have all of the documents above, then they will let you proceed. You will need to pay around $25 for the processing fee if they accept your application.

1. The Written Test

There are two written test options; first is the paper test, and second is the computer test (the one I took).

The test consist of 25 multiple choice questions, if you do your assignment by reading the Texas drivers license handbook several times and do the review questions in the back part of the handbook (yes, there is a review question section), you will be good.

If you’re lazy to answer the questions, you can check Wen’s blog, he answered most of the questions already.

If you pass the written test, they will let you schedule for the driving test. You will receive an appointment slip.

2. The Driving Test

Yup, the last and most important test to get the Drivers License. The Driving test is a 20 minute test in which the examiner will seat beside you and make you go to the street around the DPS office and grade how well is your driving skills.

To take the driving test you must have the appointment slip that you got after the DPS officer find the driving test schedule for you, car insurance, car inspection, car registration, and an ID.

First the examiner will ask you to turn on the left/right signal, test the horn, and brake light.

In Texas, the first part of driving test is the parallel parking and it will be in the DPS office parking area. You will be asked to park the car in between two poles beside the curb. Make sure you practice your parallel parking well, because if you hit the pole, you will fail automatically.

For tutorial videos about parallel parking, check my youtube ‘Parallel Parking’ playlist here.

If you pass the parallel parking, then you will be asked to drive out of the DPS office and go to the street.

Make sure you do these things:

Stop completely at the STOP sign, if you do rolling stop you will fail.
Turn left or right correctly (turn the signal, look at the mirrors, look over shoulder) and make sure you see it’s safe to turn.
Observe the speed limit.

You will then be asked to return to the DPS office, don’t worry you don’t need to memorize how to go back, the examiner will guide you.

After the test, the examiner will tell you what are your mistakes and whether you pass or fail.

3. The Temporary Driver License

If you complete the driving test successfully (that means you pass), the examiner will ask you to go inside and wait for couple of minutes till one of the officer inside print your temporary driver license.

Congratulations, you are now allowed to drive in the street! Make sure to drive carefully and follow all the things you have learned through.

Medical Technology / Medical Laboratory Science Curriculum of Adventist University of the Philippines

djitz — Mon, 18 Apr 2011 04:11:19 +0000

Recently when I check my blog visitors, I notice that some people got to my blog from Google and they were looking for the BS Medical Technology curriculum.

As far as I know, people is always curious about Medtech courses because it’s not a common course like nursing or medical doctor. Every time I got a job interview, the interviewer always ask me what actually is Medical Technology.

I’m not going to answer that question here, because I’ve actually wrote a blog post about it here.

But this time I want to share with you what the medtech students learn in their course and I hope this will give some help for those who are considering medtech (or medical laboratory science, it’s current name) as their degree.

(*To open the document in Google Docs and download it, click this link.)

How To Check if a Relation is in BCNF, 3NF, or Both

djitz — Sun, 28 Nov 2010 22:52:31 +0000

Another note of my database lecture class regarding Normalization and checking whether a relation is in BCNF, 3NF, or both.

The textbook that I use is “Database Management System” by Ramakrishnan and Gehrke and though it is a very comprehensive textbook, it is not that easy to understand. The discussion about BCNF, and 3NF was so wordy and has few examples.

So this is my way of making notes that will help myself on the final exam later, and I hope it can help you also understanding the BCNF and 3NF relation.

BCNF Relation

Probably you’ve heard the definition of Boyce-Codd Normal Form, and let’s repeat it again:

A relation in in BCNF if for every non-trivial FD X → A, X is a superkey.

Now, this doesn’t help at all, does it? But an example will surely help:

Example #1 :
ABCD
AB → CD

The steps are :

Find the candidate keys (We will not discuss how to find candidate keys here).
Check if all the FD satisfies the definition.

For example #1:

The candidate key is only one, that is AB.
Fortunately that AB is also our left hand side FD (AB → CD), so the relation is in BCNF.

Example #2 :
ABCDE
AB → CD
E → A
D → A

Candidate key : BE.
Unfortunately, all the left hand side FDs does not include BE, so the relation is not in BCNF.

3NF Relation

Third Normal Form (3NF) is a bit more relaxed form compared to BCNF. Let’s see the definition:

A relation is in 3NF if for every non-trivial FD X → A, X is a superkey or A is part of some key for R.

Once again, it doesn’t help much until we see the example. So let’s go back to our previous examples.

Example #1 :
ABCD
AB → CD

The steps are the same with checking for BCNF.

Candidate key is AB, and
Our only FD’s left hand side is equal to that candidate key, so it is in 3NF.

Honestly, you don’t need to check for 3NF for the first example, because all relation that is in BCNF is also in 3NF.

Example #2 :
ABCDE
AB → CD
E → A
D → A

Candidate key : BE.
Let’s check the FDs one by one:

E → A : this is not ok, because E is not a candidate key, and A is not part of BE.

Do you have examples of relation that is not in BCNF but it is in 3NF?

Sure I have!

Example #3:
ABCD
ABC → D
D → A

Let’s check this relation for both BCNF and 3NF.

BCNF check:

Candidate keys : ABC and BCD.
Check the FDs:

ABC → D : ABC is a candidate key.
D → A : D is not a candidate key, so it is not in BCNF.

3NF check:

Candidate keys : ABC and BCD.
Check the FDs:

ABC → D : ABC is a candidate key.
D → A : D is not a candidate key, BUT A is part of candidate key (ABC), so it is ok.

Since both are okay, this relation is 3NF.

That’s all there is in regards to determining whether a database relation is in BCNF or 3NF, it’s not that confusing at it appears to after all.

Questions and critics are welcome! And if you have a relation example that you are not sure of, you can ask in the comments section.