[om-list] C# vs. Java

[Mark Butler]

Here is an interesting comparison of C# and Java:

  http://www.prism.gatech.edu/~gte855q/CsharpVsJava.html

The languages are similar on a superficial level, but have several critical differences.  Coming from a C++ background, C# is a language I would like to program in, and Java is not (although I have to anyways).  Some of the major reasons follow:

1. Operator overloading in C# allows one to write types with value semantics, as opposed to Java, where a string or a complex number isn't equal to another "object" with the same value.  This is the opposite of the way we think in real life.  The *only* thing important about a complex number is its value - not where it is stored on memory or any other perverse notion of identity.  Two different instances of the same value should be treated as semantically identical, as in natural languages.

2. C# implements types that can be allocated on the stack or in large arrays without heap allocations for each element. A heap allocation is generally three orders of magnitude slower than stack based allocation. In short, unless you have heap allocation and garbage collection in hardware, this weakness makes it impossible to develop high performance systems in Java. That is why fast Java GUI is an oxymoron. No amount of just in time compilation can remove this heap allocation overhead in Java - your only option is to stick to primitive (i.e. non-object) types.  C# has a very clean solution for this problem.

3. C# has a notion of properties, which have all the encapsulation advantages of getter/setter methods in Java, without forcing you to write all your code using exceeding ugly GetXXX()/SetXXX() method calls.

4. C# does not force you to split every public class into its own file, let alone force you to build an umpteen level directory structure to make a reasonable program.

5. C# implements a reasonable subset of #ifdef/#else/#endif functionality for build configuration. This is *extremely* useful.

6. Other very helpful C# features missing in Java: parameter passing by reference, enums.

7. C# is based around an architecture designed to allow cooperative development in a wide variety of languages, where Sun's support for Java is the more typical Microsoft style my way or the highway...

In short, as long as we have compatible implementations on open systems (e.g. the Mono project), I believe that C# will become the most significant development to come out of Microsoft in a decade, one that is likely to bury Java on the merits and force Sun to develop a Java++ with similar capabilities. Visual Basic and COM will be blips in comparison.

 - Mark