Why you should learn C and not Scala

Jimmy: Hey, I started to learn JAVA, the object oriented programming languague. I’d like to become a programmer

Me: very good Jimmy

Jimmy: But I am a bit confused.

Me: Why ?

Jimmy: for example, Java Strings can be split but I cannot join them back from an array like. anArray.join(” “)

Me: Well Jimmy this is not implemented, but you can use google collections library and write  Splitter.on(’,').split(”foo,bar”) or String s = Joiner.on(”, “).join(numbers);

Jimmy: Wow this is cool

Me: Yes isn’t it ?

Jimmy: But those Joiner and Splitter classes and their methods are static ? Why do we use static methods here, I thought we use objects and their methods and not static helpers. they’r like functions I know from C.

Me: Yes.

Jimmy: I have a great Idea, I’ve learned about those subclasses; we could implement a subclass from java.lang.String or java.lang.Array and implement join and split.

Me: No you can’t, they’r final classes

Jimmy: Ouch… yes and I’ve learned we could’t change final classes.

Me: Yes, Jimmy right. Think you’ve got points on your exam for that

Jimmy: Since we use all these functions, should I learn C now ?

Me: No, Jimmy.

Jimmy: I started to read a great book. It advises me to use those Generics thing with collections like List or Maps.

Me: Great Jimmy, Generics is new stuff introduced with Java 5.

Jimmy: But Java 5 is already End Of Life

Me: Yes Jimmy, but Generics are still some kind of new.

Jimmy: Yeah, I’ve heard its so cool to use Generics and I’ve read I should use Generics in all my new code.

Me: Great Jimmy, you’r a fast learner.

Jimmy: I’m a bit confused.

Me: Why ?

Jimmy: I was not able to declare a map like this: Map<String, int>

Me: Well Jimmy, you can’t put a primitive type into a Generic Map. You only can put objects into it. Use Map<String, Integer> instead.

Jimmy: But I’ve read in the great book, that I should avoid Boxed Primitive Types and those Integer and Long types are new since Java 5

Me: Yes, but you have to use them with Generics like your example; otherwise don’t use them as advised, they have a few side effects.

Jimmy: Ah I see, I should not use Objects but primitive types.

Me: Sometimes yes, Jimmy, sometimes no.

Jimmy: Ok, hey I’ve got a bit to feel like an expert now.

Me: You’ll pass your JCP exam for sure.

Jimmy: Yeah, Java is a great language. Things like threading are so easy, just place synchronized in front of a method and I’m safe.

Me: Not exactly.

Jimmy: Why ? “Threading is implemented right into the languague (TM)”

Me: You souldn’t use threads in Swing or JEE.

Jimmy: Not ? Well JEE comes after my JCP exam, then I wan’t to become a Developer and then a Business Component Developer.

Me: Great Jimmy, great.

Jimmy: But if I can’t use threads in JEE or objects and subclasses why should I learn that now ?

Me: Scaling up business applications in JEE is a container thing; the container knows better how to scale your application.

Jimmy: Yes, I’ve heard from those big scaleable application containers. Threading, Transactions, Clustering… ALL built in.

Me: Yes, big business.

Jimmy: and User Interfaces like Swing ?

Me: Well with Swing you can use SwingUtilities.invokerLater and pass a Runnable to it.

Jimmy: I see. So I use one of those static methods to make my User Interface like a single threaded application ?

Me: Yes Jimmy, Swing is not multithreaded.

Jimmy: I see, like Adobes Flex and ActionScript3 ? They use a single threaded VM I’ve heard.

Me: Yes Jimmy.

Jimmy: And JavaScript, they also have  Single Threaded VMs. So why the synchronized keyword and what should we do with all the Multicore CPU’s we’ve around ?

Me: Well Jimmy, the Compiler knows better how to deal with your CPU cores.

Jimmy: Like the containers in JEE ?

Me: Yes, like that.

Jimmy: Yeah like google. So google uses JEE to scale their applications like GMail up to their millions of happy users ?

Me: No. They built their own system.

Jimmy: Like GWT ?

Me: yes.

Jimmy: Its JavaScript ?

Me: Yeah, Java compiled to JavaScript.

Jimmy: Cool. I’ve heard they also compile JAVA code to bytecode and then transform them to the Dalvik VM.

Me: Yes, Dalvik is a VM for mobile devices.

Jimmy: Why don’t they use JavaME ? Mobile Edition, its made for mobile devices.

Me: Dalvik performs better and reduces bytecode size.

Jimmy: Cool. Iv’e heard about all those Script languagues recently. Is JavaScript a successor of Java then ?

Me: No.

Jimmy: But, JavaScript has things like function objects, the same as ActionScript3 has.

Me: Yeah. Nice to use.

Jimmy: The same as code blocks ?

Me: Yea, but they are called Closures.

Jimmy: They’r cool. Since Java 5 is not anymore so new, Java 6 is here and JDK 7 is comming soon, does JDK7 have function objects or closures ?

Me: No.

Jimmy: And array Joiners ?

Me: No.

Jimmy: But where is innovation then ?

Me: Jimmy, you should open your view and see the Big-Picture.

Jimmy: Ah… you mean backward compatibility ?

Me: Yes, Jimmy. Great, u’r a fast learner. I think you can skip the Developer and go right to System Architect.

Jimmy: Thanks I was always quick in gaining things.

Me: Nice, Jimmy.

Jimmy: So, with all those millions of Java Users, and trillions of lines of JAVA code; we can’t introduce things like closures, blocks, symbols and properties ?

Me: You mean symbols like in Ruby ?

Jimmy: Yes, I’ve done a Website for my sister in Ruby on Rails. Symbols are way cool.

Me: Ah I see.

Jimmy: Yeah Ruby, but none of my friends know about this Ruby thing.

Me: Its an old and quite mature languague now.

Jimmy: Yeah, like Smalltalk ?

Me: Yes.

Jimmy: It looks so strange to me ?

Me: Why.

Jimmy: Well, I miss all those braces and it has curious keywords.

Me: Well its different.

Jimmy: Like scala ?

Me: Yes. Like scala and like Smalltalk.

Jimmy: Smalltalk, I’ve heard about. It also has a VM.

Me: It had.

Jimmy: And evereything is an object.

Me: It was.

Jimmy: And it had a big memory footprint.

Me: Yes it had.

Jimmy: Like Java ?

Me: Yes, somehow like Java.

Jimmy: Does Any1 use Smalltalk these days ?

Me: No.

Jimmy: Buts its pure OO.

Me: Yes, we don’t use it, because its too strange and doesn’t look like C.

Jimmy: Ah, I see not like C. Same as Scala doesn’t ?

Me: Yes.

Jimmy: Yeah, yesterday I saw this piece of code from ScalaTest.org:

"A Stack" should "pop values in last-in-first-out order" in {
    val stack = new Stack[Int]
    stack.push(1)
    stack.push(2)
    stack.pop() should equal (2)
    stack.pop() should equal (1)
  }

Me: Aha.

Jimmy: I was surprised and irritated when to use, for example, the word Stack in a String or not. Or “in” in a String or not.

Me: Yes, the code looks like beautiful.

Jimmy: But how should I refactor this ?

Me: Well Jimmy I have to go now… since you’r a fast learner you’l catch that too.