Why Java Sucks and Csharp Rocks

7/28/2019 Why Java Sucks and Csharp Rocks

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Why

Java Sucks & C# RocksZhaoJie @ SNDAApril, 2010


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Experiences

Pascal, VB 5 & 6, Delphi before 2002 Java programmer from 2002 to 2004

C# programmer since 2004


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Im going to talk about ...


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Languages features

Programming paradigms

Usage patterns

Why we should throw Java language away


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Im NOT going to makeyou ...


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Believe CLR is better than JVM

Believe .NET is better than Java platform

Get rid of Java language right away

Use C# instead of Java language

Use .NET instead of Java platform


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2002 - Java 1.4 & C# 1.0 2004 - Java 5.0 & C# 2.0 2006 - Java 6 2008 - C# 3.0 2010 - Java 7 & C# 4

Timeline


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So Java programmers,hold your breath ...


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Lets start from thevery beginning ...


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Is Java a pure object-oriented language?


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No.Primitive types are not

objects.


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ArrayList list = new ArrayList();list.add(5); // cannot compileint i = (int)list.get(0); // cannot compile

int hash = 3.hashCode(); // cannot compile

In Java you can NOT ...


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You have to ...

ArrayList list = new ArrayList();

Integer five = Integer.valueOf(5);list.add(five);int i = ((Integer)list.get(0)).intValue();

Integer three = Integer.valueOf(3);int hash = three.hashCode();


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In C# ... No primitive types

All types are subtypes of Object. Just value types and reference types Programmers can build custom value types Value types can be assigned to Object

variables without explicit casting.


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So you can always ...

ArrayList list = new ArrayList();list.Add(5);int i = (int)list[0];

int hash = 3.GetHashCode();


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Thank God!Here comes Java 5.0!


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Finally you can ...

ArrayList list = new ArrayList();list.add(5); // auto boxing

// auto unboxingint i = (Integer)list.get(0);

// you still cant do this!int hash = 3.hashCode();


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Java 5.0 also brings ... Annotation - allows language constructs to

be tagged with additional data Enumerations - the enum keyword

creates a typesafe, ordered list of values Varargs - make passing an array as

parameter easie r then b efore Enhanced for loop - simplied iteration
http://en.wikipedia.org/wiki/Type_safetyhttp://en.wikipedia.org/wiki/Type_safetyhttp://en.wikipedia.org/wiki/Type_safetyhttp://en.wikipedia.org/wiki/Type_safety


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But most of thesefeatures were alreadyprovided by C# 1.0 ...


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... so who is thecopy cat?


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OK, lets forget it andlook deep inside ...


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Annotations in Java areinterfaces.

Attributes in C# areclasses.


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Differences?Lets start coding!


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Annotations shortages

Strange convention Anemic object Hard to unit test


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Well, Java 5.0 alsobrings Generics, but ...


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Type erasure: typeinformation will be lost

after compiling!


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Whats the output?

List a = new ArrayList();List b = new ArrayList();

bool sameType = a.getClass() == b.getClass();System.out.println(sameType);


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And you cant do this

public class MyClass {public static void myMethod(Object item) {

if (item instanceof E) { // Compiler error...

}E item2 = new E(); // Compiler errorE[] iArray = new E[10]; // Compiler error

}}


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And use-site varianceis strange and stupid.


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Well, maybe Im biased.I can give you a

separate talk about it.


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Let keep moving.


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The same time Javareleased 5.0 ...


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C# 2.0 comes with

Better generics (comparing to Java 5.0) Anonymous methods (hello, closure!) yield keyword - iterator creation cant be

more easier


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Why closure matters?


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And yield is onlyabout iterator?


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Lets see some samples.


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So closure and yield are ...

Increasing productivity dramatically

Coming with new programming patterns Important features for async / parallel /

reactive programming

The primitives for Fibers - lightweightcomputation units


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Two years after C# 2.0, Java 6 released with ...


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Nothing!


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Nothing!!


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Nothing!!!


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Give me a break andleave me alone ...


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OK, I admit it ...


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Java 6 is cool because of ...

pluggable annotations (JSR 269): customized

compile-time processing (Project Lombok) dramatic JVM improvements: compiler

performnace, start-up time, GC, JIT...

scripting language support (JSR 223): Rhino JavaScript for Java included
http://en.wikipedia.org/wiki/Rhino_%2528JavaScript_engine%2529http://en.wikipedia.org/wiki/Rhino_%2528JavaScript_engine%2529http://en.wikipedia.org/wiki/Rhino_%2528JavaScript_engine%2529http://en.wikipedia.org/wiki/Rhino_%2528JavaScript_engine%2529http://projectlombok.org/http://projectlombok.org/


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But were talking aboutlanguage, so ...


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Lets move on toC# 3.0,

which brings us ...


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LINQ(Language Integrated

Query)


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Only LINQ?


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Yes! The great LINQ!


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LINQ is made up of ... Extension method - safely add methods to

types without breaking anything

Lambda expression - make C# a betterfunctional language Anonymous type - compile time auto

generated types Expression tree - language-level code in the

form of data


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Now tell me, which onedo you prefer?


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BBCode to HTML

// Java

Util.stripWhites(Util.stripXss(Util.bbToHtml(bbCode)))

// C#bbCode.BBToHtml().StripXss().StripWhites()


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Sorting an array// C#users.Sort((u1, u2) => u1.Age - u2.Age);

// JavaArrays.sort(users,new Comparator() {

public int compare(User u1, User u2) {return u1.Age - u2.Age;

}});


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JSON Output (C#)

List userList = ...;var json = new {

errorCode = 0,message = "OK",users = userList.Select(u => new {

name = u.FirstName + " " + u.LastName,age = (DateTime.Now - u.BirthData).Year

}),};


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JSON Output (Java)JSONObject obj = new JSONObject();obj.put("errorCode", 0);obj.put("message", "OK");

JSONArray userArray = new JSONArray();for (User u: userList) {

JSONObject objUser = new JSONObject();objUser.put("name", /* get full name */);objUser.put("age", /* calculate age */);

userArray.add(objUser);}

obj.put("users", userArray);


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Is C# just full of Syntactic Sugar?


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I dont think so.


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It really changed my mind

Real-world Functional Programming Write declarative code (anti-for) Make code / API more and more elegant


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Please write a programto index a list of

keywords (like books).


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Explanation

Input: List Output: Map The key of map is a to z

Each list in the map are sorted


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Lets see the Java coderst ...


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List keywords = ...;Map result = new HashMap();

for (String k: keywords) {char firstChar = k.charAt(0);

if (!result.containsKey(firstChar)) {

result.put(firstChar, new ArrayList());}

result.get(firstChar).add(k);}

for (List list: result.values()) {Collections.sort(list);

}


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List keywords = ...;Map result = new HashMap();

for (String k: keywords) {char firstChar = k.charAt(0);

if (!result.containsKey(firstChar)) {

result.put(firstChar, new ArrayList());}

result.get(firstChar).add(k);}

for (List list: result.values()) {Collections.sort(list);

}


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Quite easy, ah?Guess how does C#

code look like?


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List keywords = ...;var result = keywords

.GroupBy(k => k[0]).ToDictionary(g => g.Key,g => g.OrderBy(k => k).ToList());


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List keywords = ...;var result = keywords

.GroupBy(k => k[0]).ToDictionary(g => g.Key,g => g.OrderBy(k => k).ToList());


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Amazing, isnt it?


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What about the Javacommunity?


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Well, the Functional Java project is out!

But ...
http://functionaljava.org/http://functionaljava.org/http://functionaljava.org/http://functionaljava.org/


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... do you really want towrite code like this?
http://functionaljava.org/examples/1.5/http://functionaljava.org/examples/1.5/


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keywords.groupBy(

new F {public Character f(String s) { return s.charAt(0); }

}).toMap(

new F {public Character f(Grouping g) {

return g.getKey();}

},new F {

public List f(Grouping g) {return g

.orderBy(new F {

public String f(String s) { return s; }})

.toList();}

});


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Its really a pain withoutlambda expressions.


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Fortunately, Java 7 willprovide a sort of lambda syntax.


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keywords.groupBy({ String k => k.charAt(0) })

.toMap({ Grouping g => g.getKey() },{ Grouping g =>

g.orderBy({ String c => c }).toList() });


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Much better,but still noisy because

of lacking ...


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Type Inference


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C# is an FPL because of

First class functions (as .NET delegates)

Elegant lambda expression syntax Enough type inference for most cases Full set of functional primitives in BCL Great extensibility (by extension method)


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Fixed-point combinatorstatic Func Fix(

Func f)

{return x => f(Fix(f))(x);

}

var fib = Fix(f => x =>x


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Is it really useful in realworld programming?


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Yes, of course.I cant live without the

functional features now.


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Let me prove it to you.


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Expression Trees


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Code as Expressions

Serializable code

Consistent coding style Strong typing Compile-time verication Generate dynamic method easily


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Many projects useExpressions.

Let me show you sth.


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Java 7 is coming Automatic Resource Management Collection Literals

Improved Type Inference for GenericsInstance Creation

Language support for JSR 292 Simplied Varargs Method Invocation Support for Strings in Switch Statements


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Most of them areprovided by C# now


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Taste a bit


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Ruby-like Markup Builder

dynamic b = new XmlMarkupBuilder();var persons = new [] {

new Person("Tom", 10),new Person("Jerry", 8)

};XElement xml =

b.persons(from p in personsselect b.person(p.Name, age: p.Age));


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Ruby-like Markup Builder

dynamic b = new XmlMarkupBuilder();var persons = new [] {

new Person("Tom", 10),new Person("Jerry", 8)

};XElement xml =

b.persons(from p in personsselect b.person(p.Name, age: p.Age));

Convariance &


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Convariance &

Contravariance Improving the generics type system More powerful and safer than Javas use-site

variance

Really a brain fucker


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Summary

(maybe I should put a table here...)


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C# always make mehappy when coding ...


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... and it brings us lotsof useful code patterns


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But Java keeps me awayfrom the great JVM


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Java is popular since its ...

Fast - designed for the JVM, as C isdesigned for the machine

Stable - its always one and only one way todo things

Easy - most of the features are quite easyto learn


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But whats wrong with Java?


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Java is too noisy

The only way to work is not simple Write more and do less Little room for smart people.


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Java is weird ...

int a = 1000, b = 1000;System.out.println(a == b); // true

Integer c = 1000, d = 1000;System.out.println(c == d); // false

Integer e = 100, f = 100;System.out.println(e == f); // true

d b


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... and becoming even more

// C#dynamic o = ...;

int i = o.SomeMethod(true, hello);

// JavaObject o = ...;

Object[] args = new Object[] { true, hello };InvokeDynamic.SomeMethod(o, args);

f h


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If JVM is machine ...

Java byte code is the machine code Java language is the ASM.


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Would you like toprogram with ASM?


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What should we do?


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Lets use C# instead!


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Just kidding

W C# i


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We cant use C# since ...

JVM is powerful Java libraries are great Platform migration is a nightmare


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So choose anotherlanguage!

L JVM


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Languages on JVM

JRuby

Jython Groovy Clojure Scala

All h l


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All these languages are

More powerful

Run on JVM Interop with Java seamlessly Mature enough Successful in real world


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Scala makes me write Java program again.

Wh S l ?


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Why Scala? a statically-compiled language a pure object-oriented languages clean & powerful generic support (including

convariance & contravariance) enough functional features actor-based programming model reall scalable


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What do you think?

C t t i


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Contact me via

Email: [email protected] Twitter: @j effz_cn Blog: http://blog.zhaojie.me/
http://blog.zhaojie.me/http://blog.zhaojie.me/http://blog.zhaojie.me/mailto:[email protected]:[email protected]


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Show me your idea ...


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... and prove it to me

F t T lk


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Future Talks

Why F# matters

Why Scala matters (TBD.) Generics in Java, Scala, C# & F# The beauty of Parallel Library Real-world reactive programming


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Thanks

Documents

Why Java Sucks and Csharp Rocks