Summary

Microsoft describes C# as a simple, modern language derived from C and C++. Because Java is also a modernization of C++, much of the syntax and built-in features present in C# are also available in Java.

C# uses the .NET Framework, and so offers built-in, type-safe, object-oriented code that is interoperable with any language that supports the Common Type System (CTS). Java does offer interoperability with C and C++, but it is not type-safe. Moreover, it is highly complex.

C# namespaces provide a much more flexible way of grouping related classes. C# file names are not bound to the classes within them as they are in Java, nor are namespace names bound to folders as package names are in Java. C# also provides a rich set of built-in value types, including type-safe enumerations, structures, and the built-in primitives that offer a robust alternative to Java's primitives.

C# provides bi-directional conversion between reference and value types called boxing and unboxing. This functionality is not supported in Java. C# supports the use of classes, complete with fields, constructors, and methods, as a template for describing types, and provides the ability to define destructors, methods called just before the class is garbage collected. C# also provides three approaches to method parameters — in (default), out, or ref.

C# also introduces the concept of method hiding, as well as supporting explicit overriding with the virtual and override keywords, and C# provides properties as an alternative to get() and set() methods as a way to access safely internal fields.