Almost six years ago I wrote an article entitled C# from a Java Developer's Perspective which is still one of the most popular comparisons of C# and Java on the Web today. This update to my 2001 article comparing the primary features of C# and Java is a few years later than I planned. Given the amount of requests I've gotten to update it to account for the changes in Java 1.5 and C# 2.0 I'm sure there are many out there who'll find it useful. Below is the table of contents so you can jump to whatever topic interests you.

1. The More Things Change The More They Stay The Same
   This section describes concepts and language features that are almost exactly the same in C# and Java.
   1. We Are All Objects
   2. Keyword Jumble
   3. Of Virtual Machines and Language Runtimes
   4. Heap Based Classes and Garbage Collection
   5. Arrays Can Be Jagged
   6. No Global Methods
   7. Interfaces, Yes. Multiple Inheritance, No.
   8. Strings Are Immutable
   9. Unextendable Classes
   10. Throwing and Catching Exceptions
   11. Member Initialization at Definition and Static Constructors
   12. Boxing
       
       
2. The Same But Different
   This section describes concepts and language features that differ either only in syntax or in some similarly minor manner between C# and Java.
   1. Main Method
   2. Inheritance Syntax
   3. Run Time Type Identification (is operator)
   4. Namespaces
   5. Constructors, Destructors and Finalizers
   6. Synchronizing Methods and Code Blocks
   7. Access Modifiers
   8. Reflection
   9. Declaring Constants
   10. Primitive Types
   11. Array Declarations
   12. Calling Base Class Constructors and Constructor Chaining
   13. Variable Length Parameter Lists
   14. Generics
   15. for-each Loop
   16. Metadata Annotations
   17. Enumerations
       
       
3. An Ever So Slight Feeling of Dèjà Vu
   This section describes concepts and language features that exist in C# that are similar to those that exist in Java but with a significant difference.
   1. Nested classes
   2. Threads and Volatile Members
   3. Operator Overloading
   4. switch Statement
   5. Assemblies
   6. Collections
   7. goto (no longer considered harmful)
   8. Virtual Methods (and final ones too)
   9. File I/O
   10. Object Serialization
   11. Documentation Generation from Source Code Comments
   12. Multiple Classes in a Single File
   13. Importing Libraries
   14. Events
   15. Cross Language Interoperability
       
       
4. Now For Something Completely Different
   This section describes language features and concepts that exist in C# and have no Java counterpart.
   1. Deterministic Object Cleanup
   2. Delegates
   3. Value Types (Structs)
   4. Run Time Type Identification (as operator)
   5. Properties
   6. Multidimensional Arrays
   7. Indexers
   8. Preprocessor Directives
   9. Aliases
   10. Runtime Code Generation
   11. Pointers and Unsafe Code
   12. Pass by Reference
   13. Verbatim Strings
   14. Overflow Detection
   15. Explicit Interface Implementation
   16. Friend Assemblies
   17. The Namespace Qualifier
   18. Iterators (Continuations)
   19. Partial Types
   20. Static Classes
   21. Nullable Types
   22. Anonymous Methods
       
       
5. Wish You Were Here
   This section describes language features and concepts that exist in Java and have no C# counterpart.
   1. Checked Exceptions
   2. Cross Platform Portability (Write Once, Run Anywhere)
   3. Extensions
   4. strictfp
   5. Dynamic Class Loading
   6. Interfaces That Contain Fields
   7. Anonymous Inner Classes
   8. Static Imports
      
6. Conclusion(2001)
7. Conclusion (2007)
8. Resources
9. Acknowledgements