Monday, January 18, 2010

Recipes in Java

Learning to Program Java with Recipes

14 amazing kids showed up yesterday for a session at Wintriss Techinical school on learning to program Java! We tackled 2 recipes durning these 2 hours, and wanted to show how to setup your own computer so you can continue at home.

Here's What you need to do to get started with the Recipes. First the quick-links, then detailed instructions below.

Download Java SDK

Download Eclipse

Download Workspace
Import Workspace

Download Java SDK

If you don't already have java on your machine you'll have to download it. How can you tell if you do have java? open an terminal window.
Mac : command+space then type terminal and hit enter
Windows : windowskey+r then type CMD and hit enter
In the terminal/command window type
java -version
if you see something like
java version "1.6.0_15"
you've got it, otherwise download it from Sun at http://java.sun.com/javase/downloads/widget/jdk6.jsp

Download Eclipse

You want to download the "Eclipse IDE for Java Developers (92MB)"
it's here
http://www.eclipse.org/downloads/

Download the Workspace

Download the "Learn To Program - In Java" workspace from CodePlex. http://learntoprogram.codeplex.com/
Unzip it to the directory of your choice. But remember the location, you will need in the next step.

Import the Workspace

In Eclipse, right click in the Navigator Window and select "Import Workspace".
A Window will appear asking for an import source, select "Existing Projects into Workspace", if you can't find it start typing existing and it will appear.
Click next.
The root directory is the location where you unzipped the workspace. then simply hit finish.

If you are successful you should see the IntroToProgramming folder in the navigator window.

That's it, Happy Programming!
If you have any questions, please feel free to email me.

Recipes in Java

Learning to Program Java with Recipes

Here's What you need to do to get started with the Recipes. First the quick-links, then detailed instructions below.

Download Java SDK

Download Eclipse

Download Workspace
Import Workspace

Download Java SDK

Download Eclipse

You want to download the "Eclipse IDE for Java Developers (92MB)"
it's here
http://www.eclipse.org/downloads/

Download the Workspace

Import the Workspace

Saturday, January 16, 2010

Mock Smells

Today, Bob Martin tweeted :

unclebobmartin

I use mocking frameworks as little as possible. I think heavy reliance on a mocking framework is a smell. I usually write my own mocks.

I agree with this. Of course the 140 characters allowed in a tweet don’t really give much space to explain what that smell is. So let’s refine our nose.

Mocks let you test implementation. Anyone who ever gets uppity about the use of stubs, fakes & mocks is paying a lot of attention to this. With a mock you can verify that something has been called. While this can be useful, it is rarely part of the Behavior of a system, and often part of the implementation. Since there are literally 1,000’s of way to program the exact same behavior, Unit tests that lock a particular implementation will actually in up “protecting” your code from being refactored. This smell tends to come up in newly written code, and is usually accompanied by the phrase

“anytime I want to change anything a bunch of tests break and I have to go and fix them”.

Mocks let you fake very hard to fake calls. Ever need to mock out a call to HttpServletRequest? There are over 40 methods on that interface. Even with the help of your IDE, that’s a pain. A good mocking framework (I prefer EasyMock) will let you do it in 2-3 lines. This is great, especially in legacy code, or API’s you don’t control. But it’s a cover for a much more insidious smell that exists in HttpServletRequest. Simply put, an interface should not have 40 methods. Now you might argue that was how many were needed to handle something as complex as a web call. And you would be wrong. Take a look at Rack (or our Port of it - JRack) it handles everything with 1 simple abstraction.

When mocks are the easiest way to gain an handle into your code, you have coupled you code too tightly, and not left enough inserts points.

Mocks let you fake calls. Lastly, mocks let you fake easy calls too. One example I use a lot is Loaders. My Loader interface looks like this:

public interface Loader<T>

{

public T load() throws Exception;

}

I will constantly be making calls like

request.init2Edit(new MockLoader<Member>(member));

But here a mocking framework is overkill. It’s so easy to write the above line, than

Loader<Member> loader = EasyMock.createMock(Loader.class);

EasyMock.expect(loader.load()).andReturn(member);

request.init2Edit(loader);

If I’ve kept my code clean, mocking frameworks just aren’t that useful.

So hopefully you will start to sense the same things in your code. Of course if your nose is prickling over some hard to test piece of code, grab your mocking framework. It’s your first line of attack. Like grabbing some cologne when you are a bit smelly and guest are coming over, just realize that eventually you have to take a bath.