public class StorageLevelObserver implements IArticleObserver
{
  private static StorageLevelObserver instance;
  private ch.hslu.appe.stock.Stock legacy;

  private StorageLevelObserver(ch.hslu.appe.stock.Stock legacy)
  {
    if(legacy == null)
    {
      this.legacy = new StockLocal();
    }
    else
    {
      this.legacy = legacy;
    }
  }
  /**
  * Gets the Singleton-Instance of a StorageLevelObserver
  * @return The StorageLevelObserver to be used.
  */
  public static StorageLevelObserver getStorageLevelObserver(ch.hslu.appe.stock.Stock legacy)
  {
    if(StorageLevelObserver.instance == null)
    {
      StorageLevelObserver.instance= new StorageLevelObserver(legacy);
    }
    else
    {
      //if(legacy != StorageLevelObserver.instance.legacy)
      //{
      //  StorageLevelObserver.instance.legacy = legacy;
      //}
    }
    return StorageLevelObserver.instance;
  }
  public void notify(IObservableArticle article, String property)  {   ...  }
}

Take a moment to realize what the code actually does, ignoring the commended part of getStorageLevelObserver()! getStorageLevelObserver() is in this case of a Singleton, is the function to construct the internal instance of StorageLevelObserver and saves the reference to the private static referencevariable instance, therefor using an if to check if the reference is already set or not. I introduced a new parameter to the getStorageLevelObserver()-Method because I needed give the Observer a stock to order Items from, if the local stocklevel is too low. (This is done within the  notify-Method! It isn’t important, so don’t bother)

Of course i also want to test such an important class, so i set up two new Testcase for two different scenarios to be testet. That’s probably the place where the legacy-Field comes in, that you have been asking yourselves about multiple times until now. Legacy holds a reference to an Instance of Stock, an Object that represents the central Stock, from whitch our stock has to order, if the local level of Items of a specific article is too low. The StorageLevelObserver -Class’s objective is to keep the local stocklevels within given boundaries!

When testing i inserted my own StockHelper-Objects, that implement the Stock-Interface, and help me checking that a change within an article correctly triggers an order to the Legacy-Stock-System, thereby filling the local stock. For the two testcases I also wrote two different StockHelpers. The beginning of each TestCase was the same: Get the StockLevelObserver-Instance by also directly passing the according StockHelper as an actual parameter. The Tests in my IDE succeded, using JUnit and Eclipse as an IDE. Me, quiet happy, ran  the tests again using ant test. The tests failed! What!?!?!?

I could not find the solution to my problem using the eclipse Debugger, and debugging using ant…Well not so much either. It puzzeled me for a while, then I got it. The singleton pattern and it’s behavior within the JVM-Environment seem to be the problem. Eclipse apparently creates a separate instance of JVM for each TestCase, while ANT doesn’t. So what exactly happend?

Using Eclipse and thereby one separate instance of the JVM for each Testcase, the singleton was created twice, using the two different StockHelpers as intended, because the block within the IF-Statement in getStorageLevelObserver() was executed twice!!! That does not happen if one and the same JVM-Instance is used for both TestCases. In that case the internal Field instance is already set and the constructor will not be called, thereby not setting legacy to the new StockHelper-Object and cause my tests to fail, because the wrong StockHelper was used the second time!

When I realized that, I created a new IF-Block whose content will be executed if the new legacy-Object differs from the old one, thereby setting legacy to the new value, without having to call the private constructor (not necessary, creates overhead only…). It solved my problem, and hopefully keeps you from being puzzeld by the same buggy code yourself.

Edit: The problem seems to be the same even if the StockHelper will not be changed during runtime. If the instance of JVM is not destroyed after one test-Run, instance might still be set, provoking the same odd behavior as mentioned above. (Apparently ANT behaves sometimes like that – that was the problem for me too)

If you need some more explanation, visit our main page.

Our journey started at Wednesday afternoon, which lasted three and a half days, till Sunday evening. Hence, as you might assume, we had to bunk off school for two days Anyway, after we sweat the alcohol from last night out of our bodies, we were ready to start.

To see all the pictures of the trip you can visit my Picasa album.

Day 1 – Albany

A 430 km drive to Albany. I’m still very amazed that you can drive on a straight road without oncoming traffic for hours. You can only hope that your car will not break down. Finally we arrived in Albany. Established in 1826, shortly before Perth, it is the oldest European settlement in WA and has a population of 25’000.
We checked-in at the Backpackers, cooked a huge amount of spaghetti and went out to a nearby pub. Although its rather small size, I think it can hold up to 50 persons, it had two security guards. No wonder is the alcohol so expensive here if almost every pub needs to employ security staff.
We started telling jokes after we had been drinking a couple of beers. It was a memorable night, very amusing and I didn’t laugh that much since a long time. Just to mention phrases like “Nei, das isch super” or “Kaffi-Creme”.

Day 2 – Augusta

The next day started early in the morning. Our schedule was very tight. We drove to the Torndirrup National Park, which lies 15 km further south of Albany, to see The Gap and The Natural Bridge. These spectacular rock formations, which also provide a beautiful view to the windswept rugged coastline, has been created by the massive power of the Southern Ocean.

We continued to the William Bay National Park, 80 km further west of Torndirrup. This place is known for its picturesque beaches, untouched coastlines and the Elephant Rocks & Elephant Caves. The intense colors and lack of tourists amplified the breathtaking atmosphere. I got sentimental because I wanted so badly to share this beautiful moment with my girlfriend, who I hadn’t already seen for six weeks. Elephant Rocks, as the name suggests, look like a herd of elephants in the midst of shallow water.

Time was our biggest enemy but we managed it somehow to visit the Valley of the Giants in the Walpole Wilderness Area, which is 40 km further west of William Bay. A highlight in there is the Tree Top Walk, on which you can walk literally between the tree crowns of 400-year-old giants in a height up to 40 meters. If you experience fear of heights you will either get rid of your phobia or crap your pants.

After finishing our walk we headed towards Augusta. Twilight was approaching fast and we had to drive very carefully as animals moving unexpectedly on roads. Particularly in twilight or during the night kangaroos ave very active and are crossing the roads more frequently. After driving further 240 km we finally arrived in Augusta around 9:30 pm. Having checked-in at our lovely YHA, we looked for somewhere to have dinner. Augusta’s population is about 1300, therefore we had no much choice. We found a big restaurant, which was close to where we stayed, but unfortunately the kitchen had already closed. However, Joel, hungry as he was, spotted some leftovers of salad from one of the staff members and asked him I he could eat it up. The cooks had mercy on us and offered us a great deal. They would warm up any leftovers from a previous wedding ceremony and just charge us 20$ in total so that they could buy another beer for themselves. They served tons of meat, filled up with vegetables, and also various salads. A perfect deal: A big dinner for 11, not more than 2$ per person. Afterwards, we all went back to our fantastic, comfortable and low priced hostel, the Baywatch Manor YHA, which I can strongly recommend for backpackers.

Day 3 – Bunbury

After having an extensive breakfast we continued our trip to visit the stunning crystal wonderland Lake Cave in Margaret River. To enter the cave first you need to stroll down about 350 steps between ancient Karri trees rising up to 50 meters into the sky. I mounted my Canon 50mm f/1.8 lens and hoped that I could take a good shoot of the crystalline beauty in extremely low-light conditions. However, this wasn’t an easy task. Without a tripod you have usually no chance at all. But with a bit of improvisation I managed to built a stable fixture with my lens hood

Check out the picture, I really think that I achieved the task successfully. Afterwards we walked to a nearby beach, where a bunch of surfers tried to catch the two meters waves, which in my opinion were to powerful.

Later on we drove to Bunbury, which is the 2nd biggest city (or shall I say village) in Western Australia. Quite surprising because compared to the 1.6 million metropolis Perth, Bunbury has only 30000 inhabitants. Different cities, different manners. We stranded in a rock pub which had a clientele of all ages. Starting from 18 years up to probably 50+. Surprisingly, women are used to grab and squeeze men’s bottom cheeks without hesitation, especially the elderly. Despite that Bunbury lies to the south of Perth, which implies lower temperatures, the chicks wore shorter skirts than their fellow citizen from the state’s capital. After having an enjoyable night in the pubs we went back to the Youth Hostel and headed back to Perth on the following day. Ah, almost forgot to mention it. If you want to eat delicious pizzas in Bunbury, have a look at Bianco’s Gourmet Pizza. I will never forget the lovely taste.

I’ve had my first CAE mock exam last week, which was split up in five categories – Writing, Reading, Use of English, Listening and Speaking. The test results enabled me to determine my English skills and to see if I’m on my way to pass the CAE. I’m very satisfied with the overall result of 76 %, which would be a B grade. But if I want to achieve the highest level in the CEFR I need to pass the CAE with an A grade or more specifically 80 % and above. This level represents the mastery or proficiency of a language.

If you’re wondering how a CAE test might look like I will show you a task from the writing part followed by my article as the corresponding answer. You’ll just get 45 minutes to read all four tasks, then you need to choose one task and write approximately 220 – 260 words. According to your chosen task this could be for example an article, a proposal, a report or an information sheet. Therefore you don’t have plenty time and you must work quickly and efficiently.

Enjoy the reading.

Task – Write an article

A technology magazine, International Technology Today, has asked its readers to submit articles on the impact of mobile phones on modern society. In your article, you should discuss the different personal and business uses of mobile phones and assess the advantages and disadvantages of this technology.

Impact of mobile phones on modern society

The aim of this article is to discuss the personal and business uses of cellular phones and their advantages and disadvantages.

Almost every reader would agree that the communication technology has changed our way of loving dramatically over the last two decades. Mobile phones were dedicated to a small range of CEO’s in their early stage of development and its main purpose was to enable businessmen to stay in touch with their partners and company – anytime and anywhere!

Nowadays, cellulars are affordable to almost anyone. Calling your beloved partner, rearranging meetings just before they start or finding someone easily in a crowded place are just a few of the many advantages provided by this technology. But it also has its drawbacks. People expect that you need to stay on wire (almost all) around the clock. It doesn’t matter anymore if you are on holiday or enjoying your sunday’s family picnic. This development leads to people being unable to “switch-off” and generates more stress.

But the device itself has also undergone a lot of changes over its lifetime. It is not a basic phone anymore, just enabling the user to make calls and text messages. In fact, it is much more powerful than average users expect. Smartphones, like the iPhone, are providing a platform to customers, highly customizable to everyone’s needs. If you get lost in a foreign town you will find your hotel easily. Just install some navigation software  over the air to your smartphone, and the lovely woman’s voice, coming out of the tiny speaker, will guide you reliably to your destination.

But be aware – the sword is double-edged. Smartphones are not as easy to use as the old intuitive mobile phones. Their long lists of features are often also their doom, resulting in very complex user interaction and handling, where non digital-natives especially can’t cope that easily.

Ocean-related fatality statistics, however, disprove this assumption. Underwater animals, like the scary white shark, are not the main reason for most casualties. Between five and 15 people are killed by sharks worldwide.

However, the number of casualties by rip currents ranks second after heat-related deaths. Surf Life Saving Australia (SLSA) estimates that between 80 and 90 people drown every year due to rip currents along Australian coastlines. They are responsible for 80 % off all surf zone rescues.

On my first day in Australia, my host-family informed me how dangerous a rip current can be. I already knew that Aussies prefer to drive on the wrong lane, but rip currents, what’s that?

A rip current, also referred to as a rip, is a moving current of water, sometimes strong or fast flowing. It will usually start near the shoreline and flow into the open deep water. It may feel like you are in a fast moving flow of water, like being in a river or you may not notice it at all.
Dragging people away from the beach, rip currents can be extremely dangerous. They often lead to drowning when swimmers attempt to fight against the current, become exhausted and begin to panic. Rips are not undertow, therefore they don’t pull people under water.

If you get caught in a rip current, don’t panic and don’t try to swim against the current. Raise your arm to call for assistance, while floating to conserve your energy. If you are confident, escape the current by swimming parallel to the beach. When free of the current, swim at an angle (away from the current) toward shore. Breaking waves can assist you back to shore.
To get a better understanding of rip currents and professional advice how to escape them just check out the SLSA and USLA websites and the following two movies.
[youtube]http://www.youtube.com/watch?v=M9OMIKsTuqY[/youtube]
[youtube]http://www.youtube.com/watch?v=FezsFM5AEsM[/youtube]

I will show you some pics here to get a better insight. You can find all the pics in my Picasa Gallery.

But if you wanna buy a bike in a huge shopping centre like kMart or Target, you could most probably face a problem, especially as a Swiss guy.
The bikes are not assembled, you just buy a huge box with all the Lego parts inside and an assembly manual. C’mon, IKEA everywhere or what? I wouldn’t even understand the manual in German.

Wayne, two hours later I finally built my brandnew bike, which I bought for only 129 AUD, without any proper tools at all. Yes, it’s not IKEA furniture, a screwdriver doesn’t suffice.

So, very happy with my new bike, I was riding to school on the next day. And what happened, I’ve had to face a whole bunch of insane wrong-way drivers on the road.
Fortunately almost all the drivers realized their fatal mistake and stopped their cars immediately. But there was this stubborn driver in his red car, heading towards me, very determined to not turn back.

But I didn’t shrink back. Still on collision course, either he or me (and of course my beloved bike) had to give up.

You can see the result on the picture below. Booya!

WARNING: Do not use the grammar of this post as a good example of English

Meine achtmonatige Backpacker Asia-Pacific Reise für das Jahr 2012 hat begonnen.

Am 30. Dezember 2011 18:40 bin ich vom Zürich Flughafen gestartet.
Der erste Zwischenstopp was Frankfurt. Von dort aus bin ich dann mit der brandneuen A380-800 der Lufthansa Richtung Singapur aufgebrochen. Laut Angaben der Lufthansa, bietet ihre Version des A380 Platz für 526 Passagiere. Zertifiziert wurde das Flugzeug sogar für 853 Passagiere (wenn es nur eine Economy Klasse gäbe).
Der Flieger ist 72.73 m lang, 24.45 m hoch und hat eine Flügelspannweite von 79.75 m. Dies macht den A380 zum grössten Passagierflugzeug der Welt. Aber das wisst ihr ja vermutlich alle, ihr habt auch Nachrichten geschaut.

Als Passagier kann man dank drei bordinternen Kameras den Flug von aussen live mitverfolgen.
Besonders eindrücklich war die Kamera, hoch oben am Heck. Von dieser hohen Perspektive erscheinen Fahrzeuge wie Spielzeugautos und die Startbahn erweckt den Eindruck, dass sie nicht für den Start ausreicht, da der A380 knapp zwei Mal breiter ist.

Als der A380 nun an seiner Startposition war und das Takeoff bekam, erwartete ich ein ohrenbetäubendes Geräusch der vier Rolls-Royce Triebwerke, die für diese Phase einen Schub von knapp 130000 PS erzeugen. Aber da war kein lautes Geräusch zu hören, nur ein dumpfes Rauschen. Würde sagen, perfekt gelungen. Leise Triebwerke, gute Isolation (in der Business und First Class sogar noch besser isoliert).
Somit konnte ich auch ein wenig schlafen (ca. 3h) auf den 12h langen Flug nach Singapur.

Aber genug geredet, hier nun einige interessante Videos zum A380.

Bilder und Erlebnisse zum Neujahr in Singapur und meiner Gastfamilie in Perth kommen noch.

Autonome Katamarane und Bojen, ausgestattet mit sensiblen Sensoren, ermöglichen die effiziente Überwachung der Wasserqualität in Seen, Lagunen und Flüssen. Eine optimierte drahtlose Kommunikationsinfrastruktur übermittelt die Messdaten zur Einsatzkontrolle.

Mit Freude gebe nun ich bekannt, dass HydroNet in den folgenden Medien erwähnt wird:

• Wächter des Wassers, Antoine Hauck, aktuelle technik 10/2011
• Babel Multi-hop Routing for TinyOS Low-power Devices, Antoine Hauck, Peter Sollberger, UBICOMM 2011
• Gewässerschutz per Hightech, Marcel Habegger, 20 min, 20. Oktober 2011
• Schwimmende Roboter für den Gewässerschutz, Jürg Oehninger, Wissen aktuell DRS1, 4. November 2011
• Schwimmende Roboter für den Gewässerschutz, Sigrid Cariola, Hochschule Luzern 3/2011