While most of the differences between Sun's J2EE Java development platform and Microsoft's .NET C# development platform exist at a strategic level, there are some significant differences for the programmer.

Platforms Compared

For years and years, the backbone of programming was the C coding language. C is very powerful and performs well because it is only once removed from the true language of computers: the CPU's binary instruction set. Then in 1983, when object-oriented programming was catching on, Bjarne Soustrup of Denmark morphed C into C++, and many stellar systems and applications have been written in C++ ever since. But through it all, C++ has had a number of shortcomings, the most serious of which is memory leaks. Unless you assiduously clean up after yourself, you can leave orphaned objects lying about doing nothing but consuming memory.

Into the mix, then, stepped Sun Microsystems. In 1991, a team at Sun developed Java, a language that is a genuine improvement over C++. With Java, a careless programmer can no longer litter the memory chips with abandoned objects, for behind the scenes all Java programs are executing an automatic maintenance process. A language like Java that automatically tidies up after itself is called a "managed" language.

Further, Java makes more sense and is easier to learn. Omitted from Java are most of the things that make C++ an onerous workmate. Sun either found a better way of doing something (like using Java delegates and single inheritance instead of the confusing multiple-inheritance model used in C++) or left it out altogether (like operator overloading.)

Through it all, Microsoft stood on the sidelines, nurturing its programmer base with the popular but limited Visual Basic language. Then in 2000, amid outcries from Sun that Microsoft had plagiarized Java, the C# language was introduced. Half a dozen years and as many lawsuits later, Microsoft has garnered some of the most enthusiastic followers of the craft into its camp and away from Java.

Differences That Matter to a Programmer

Aside from platform considerations, the differences in programming in Java or in C# are considered to be minor, unless they happen to affect your preferred way of doing things. For example, if you like to manipulate arrays by address pointer arithmetic, you'll have to change your ways if you're going to code in Java; that feature is not available.

Graphic Interfaces in C# and Java

For my money, the biggest difference in the two languages is the way GUI programming is done. In Java, which is intended to be run on multiple platforms, graphic interface components are laid out dynamically by an agent called a "layout manager." Coding for the layout manager can be a tedious enterprise, and the overall look of the interface can suffer. Further, the way that Java handles container relationships and GUI events, like screen painting, can take some getting used to.

C#, on the other hand, handles graphic components more like it's been done in Visual Basic. There is no layout manager to deal with, and coding is simplified. Similarly, the code that enables Java components to respond to events is bulkier and more obscure than C#'s counterpart. The trade-off for the convenience of C#, however, is a stickier task of moving C# GUI applications to non-Windows platforms.

C# Coding Features

There's no question that C# is a more feature-rich language than Java, with more options available to the programmer. A glowing example is C# properties.

Coding variables as private and creating methods to set or retrieve the variable's value is considered to be good coding practice, but it's a pain. C# lets you define a private variable and immediately create public methods to encapsulate a Set and a Get:

Then, elsewhere in your code, you can access the private variable through its public property:

myClass.MyProperty = 1; or int i = myClass.MyProperty;

The code within the property's Get or Set methods will be executed automatically.

Java's equivalent is done in the more verbose way with user-named Get and Set code and explicit calls to invoke those methods:

This is the calling code:

Operator Overloading and In-Line C Code

Operator overloading is allowed in C# but not in Java at present, and the issue has become an old chestnut of discussion at some programmer forums. As with properties, Java can get along without operator overloading; it just takes more code, that's all.

C# has the ability to incorporate in-line C code. This allows you to use pointer arithmetic, but Microsoft discourages the practice as that technique is considered to be unsafe. Pointer functions are dangerous because of a lack of type-matching. If I have created a pointer to an array of integers, for example, and then treat it as a pointer to a double by mistake, there is no way for the compiler to catch it. In C#, you have to disengage type-safe coding constraints with the "Unsafe" method keyword and compiler directives.

Other Things C# Has That Java Doesn't

• Multiple classes in a single source file—Makes source code maintenance easier
• Aliasing—Support for resolving conflicting namespace problems
• Structs—A convenient way to consolidate associated variables into a complex user-defined type; very handy for passing many parameters under a single name
• Param, Ref, and Out—Add flexibility when passing parameters to a function
• Jagged arrays—Support for multidimensional arrays of varying length
• Enumerations—Logical treatments for related values
• is operator and as operator—Useful for discovering and resolving object type differences
• Indexers—Parameters for identifying an object as an array element
• Verbatim strings—A simplification of the nuisance escape-character notation (@"...")
• Attributes and reflection—Metadata about the application itself
• IDisposable—Provides a method to release unmanaged resources that have been allocated
• Explicit virtual methods—Allow a class to implement methods of an interface, separate from its own class methods
• Preprocessor directives—Support for conditional compilation and source code grouping and outlining

Things Java Has That C# Doesn't

Java allows static methods in an interface, and C# does not. Some programmers use this feature in Java to act like an enumeration in C#. Other Java programmers claim that interfaces are a template or contract as to how a method should be implemented and that static methods have no place in there.

Java also has support for ensuring that floating point values are preserved across platforms as well as better support for error-trapping and -handling.

Java Feature Creep

So why are there so many more features in C# than Java? Largely because C# is closely tied to the Windows operating system and Java is platform-independent. Java must be accommodating of the OS that it's running on, so many options are either not available or are much more difficult to implement. In the future, though, when the next version of Java is released, we may see many of the missing features come into the language.

Originally, Java was a compact language intended for small consumer products like cell phones. But then it caught on in more and more areas and became the de facto standard for intelligent Web-based and desktop applications. Then came Java applets that run in a browser and Java servlets that run on a server and then the most powerful version of Java, J2EE (Java Enterprise Edition), to provide services, integration, and cross-platform support.

There are now three flavors of Java:

• The Java 2 Platform, Micro Edition (J2ME) for handheld devices and small appliances
• The Java 2 Platform, Standard Edition (J2SE) for desktop applications
• The Java 2 Platform, Enterprise Edition (J2EE) for large server systems

Originally, Java was a standalone language, but now, as a result of the growing process that all vibrant languages must undergo, J2EE can accommodate cross-platform systems with Java Connectivity Architecture (JCA). JCA allows Java enterprise applications to interface with existing non-Java enterprise applications like SAP.

Playing Inside of the Sandbox

Java and C# are much more alike than they are different. Essentially, Microsoft recognized the triumphs of Java over C++ and outright copied much of it. Figured they could just buy their way out of any legal problems, you see. For the rest of C#, they simply took a page from their own Visual Basic playbook. The result is considered by many to be the sweetest coding platform available.

Chris Peters has 26 years of experience in the IBM midrange and PC platforms. Chris is president of Evergreen Interactive Systems, a software development firm and creators of the iSeries Report Downloader. Chris is the author of The i5/OS and Microsoft Office Integration Handbook, The AS/400 TCP/IP Handbook, AS/400 Client/Server Programming with Visual Basic, and Peer Networking on the AS/400 (MC Press). He is also a nationally recognized seminar instructor and a graduate instructor at Eastern Washington University. Chris can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..