Editing Comparison of C Sharp and Java (section)

=== Unified type system ===
Both languages are statically typed with class-based object orientation. In Java the [[primitive types]] are special in that they are not [[object-oriented]] and they could not have been defined using the language itself. They also do not share a common ancestor with reference types. The Java [[reference type]]s all derive from a common root type. C# has a unified [[type system]] in which all types (besides unsafe pointers<ref name="unsafe pointers">{{cite web |url=https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/unsafe-code#pointer-types |title=Unsafe code, pointer types, and function pointers |publisher=learn.microsoft.com |date=29 May 2022 |access-date=14 April 2023}}</ref>) ultimately derive from a common root type. Consequently, all types implement the methods of this root type, and extension methods defined for the {{mono|object}} type apply to all types, even primitive {{mono|int}} literals and [[Delegate (CLI)|delegates]]. This allows C#, unlike Java, to support objects with encapsulation that are not reference types.

In Java, compound types are synonymous with reference types; methods cannot be defined for a type unless it is also a ''class'' reference type. In C# the concepts of encapsulation and methods have been decoupled from the reference requirement so that a type can support methods and encapsulation without being a reference type. Only reference types support [[virtual method]]s and specialization, however.

Both languages support many [[built-in type]]s that are copied and passed by value rather than by reference. Java calls these types [[primitive type]]s, while they are called ''simple types'' in C#. The primitive/simple types typically have native support from the underlying processor architecture.

The C# simple types implement several [[Interface (object-oriented programming)|interfaces]] and consequently offer many methods directly on instances of the types, even on the literals. The C# type names are also merely ''aliases'' for [[Common Language Runtime]] (CLR) types. The C# {{code|System.Int64}} type is exactly the same type as the {{mono|long}} type; the only difference is that the former is the canonical [[.NET]] name, while the latter is a C# alias for it.

Java does not offer methods directly on primitive types. Instead, methods that operate on primitive values are offered through companion [[primitive wrapper class]]es. A fixed set of such wrapper classes exist, each of which wraps one of the fixed set of primitive types. As an example, the Java {{mono|Long}} type is a [[reference type]] that wraps the primitive {{mono|long}} type. They are ''not'' the same type, however.