Ear Bleeding Java Generics

In my previous post, I blather on about my adjustment to Java from C#.

Now that I’ve had a little while, I’ve been adjusting a bit better.

I am realizing that a simplistic “port” is not what I am doing.

I am doing a “translation”.

I do not let curly braces fool me.

Just because both are present in C# and Java does not mean that I can express the same concepts in the same way.

Sometimes I cannot even express a concept in a similar way.

I started with my C# classes that deal with boards and mazes.

In C#, these are highly genericized.

So, I set out to write them in Java in a highly genericized manner.

Doing this was a mistake.


Three reasons.

One, I think my original solution may have been a bit on the “clever” side. The one true thing about all clever code is that it will come back to bite you later. I use generic types for the contents of a board cell, the contents of a maze cell (which is actually a subclass of board cell), the contents of a portal between maze cells. Relying on the language feature in C# that enables me to instantiate these classes, I used them mercilessly. In Java I needed to switch over to interfaces and factory classes, because the templates started to get really confusing.

Two, there was a significant design flaw in my C# code. This is common with organically grown code like this. I have a number of static (read “global”) objects for dealing with things like the item and creature lists. Recently, I decided that this was not the best way to go about things.  I also don’t have one large “game” object, which I normally do in cases like these, to contain all of the subordinate game objects and state. I decided to restructure so that the static classes were no longer static, and that the various tables would be put together into a single tableset, and this tableset object would be given to the various other classes that need them.

When translating to Java, I noticed that things would be a lot easier if everything knew what its parent was, and could talk up and down the hierarchy. There should be the big Game object, which is the parent of the tableset and the maze (which is the chief other object in the game), and so I attempted to do this with typed generics in Java, with a nifty interface (also generic) that allows specification of a type of parent. I was going along quite well until I got to a class that would need five template parameters, at which point I decided to ditch generics entirely, and use interfaces and the “Object” class for the parent.

Don’t get me wrong. I’m fine with generics, but my limit is type parameters. After that, my ears start to bleed.


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