| Data types | Java | C# |
|---|---|---|
| Single-root (unified) type system | No | Yes |
| Signed integers | Yes; 8, 16, 32, 64 bits | Yes; 8, 16, 32, 64 bits |
| Unsigned integers | No | Yes; 8, 16, 32, 64 bits |
| Character | Yes | Yes |
| Date/time | Yes; reference type | Yes; value type |
| IEEE 754 binary32 floating point number | Yes | Yes |
| IEEE 754 binary64 floating point number | Yes | Yes |
| High precision floating point number | No; but see Arbitrary size decimals | 128-bit (28 digits) Decimal type |
| Boolean type | Yes | Yes |
| Strings | Immutable reference type, Unicode | Immutable reference type, Unicode |
| Arbitrary size integers | Reference type; no operators | Yes |
| Arbitrary size decimals | Reference type; no operators | No |
| Complex numbers | No | Yes |
| Reference types | Yes | Yes |
| Arrays | Yes | Yes |
| Value types | No; only primitive types | Yes |
| Enumerated types | Yes; reference type | Yes; scalar |
| Lifted (nullable) types | No; but wrapper types | Yes |
| Tuples | No | Yes |
| Pointers | No | Yes |
| Reference types | Java | C# |
| Garbage collection | Yes | Yes |
| Weak references | Yes | Yes |
| Soft references | Yes | No |
| Proxy support | Yes; proxy generation | Yes; object contexts |
| Object initialization | Bottom-up (fields and constructors) | Top-down (fields); bottom-up (constructors) |
| Object orientation | Java | C# |
| Classes | Yes | Yes |
| Interfaces | Yes | Yes |
| Abstract classes | Yes | Yes |
| Member accessibility levels | Public, package, private, protected | Public, protected, internal, protected internal, private |
| Class level inner classes | Yes | Yes |
| Instance level inner classes | Yes | No |
| Partial classes | No | Yes |
| Deprecation/obsolescence | Yes | Yes |
| Overload versioning | Some | Yes |
| Properties | No | Yes |
| Events | No | Yes |
| Operators (operator overloading) | No | Yes |
| Indexers | No | Yes |
| Implicit conversions | No | Yes |
| Explicit conversions | No | Yes |
| Fields and initialization | Java | C# |
| Fields | Yes | Yes |
| Constants | Yes | Yes |
| Static (class) constructors | Yes | Yes |
| Instance constructors | Yes | Yes |
| Finalizers/destructors | Yes | Yes |
| Instance initializers | Yes | No |
| Hierarchy initialization | Top-bottom, lexical order | Top-bottom-top, lexical order |
| Object initializers | No | Yes |
| Collection initializers | No; can be modelled | Yes |
| Array initializers | Yes | Yes |
| Methods and properties | Java | C# |
| Virtual | Virtual by default | Non-virtual by default |
| Abstract | Yes | Yes |
| Sealing | Yes | Yes |
| Explicit interface implementation | No | Yes |
| Value (input) parameters | Yes | Yes |
| Reference (input/output) parameters | No | Yes |
| Output (output) parameters | No | Yes |
| Variadic methods | Yes | Yes |
| Optional arguments | No | Yes |
| Named arguments | No | Yes |
| Generator methods | No | Yes |
| Extension methods | No | Yes |
| Conditional methods | No | Yes |
| Partial methods | No | Yes |
| Generics | Java | C# |
| Reified generics | No | Yes |
| Co-variance | Yes | Yes |
| Contra-variance | Yes | Yes |
| Reference type constraint | Yes; implicit | Yes |
| Value/primitive type constraint | No | Yes |
| Constructor constraint | No | Yes |
| Relation constraint | Yes | Yes |
| Primitive/value type support | No | Yes |
| Migration compatibility | Yes | No |
| Functional programming | Java | C# |
| Delegates/method references | No | Yes |
| Closures/lambdas | No; some use cases covered by anonymous inner classes | Yes |
| Expression trees | No | Yes |
| Query expressions | No | Yes |
| Runtime (dynamic) binding | Java | C# |
| Late-bound (dynamic) type | No | Yes |
| Runtime type information and manipulation | Java | C# |
| Runtime type information | Yes; but with type erasure | Yes |
| Runtime generics realization | No | Yes |
| Runtime type construction | No; third party tools exist | Yes |
| Statements | Java | C# |
| Loops | Yes | Yes |
| Conditionals | Yes | Yes |
| Flow control | Yes | Yes |
| Assignment | Yes | Yes |
| Exception control | Yes | Yes |
| Variable declaration | Yes | Yes |
| Variable type inference | No | Yes |
| Deterministic disposal (ARM-blocks) | No | Yes |
| Expressions and operators | Java | C# |
| Arithmetic operators | Yes | Yes |
| Logical operators | Yes | Yes |
| Bitwise logic operators | Yes | Yes |
| Conditional | Yes | Yes |
| String concatenation | Yes | Yes |
| Casts | Yes | Yes |
| Boxing | Yes; implicit | Yes; implicit |
| Unboxing | Yes; implicit | Yes; explicit |
| Lifted operators | No | Yes |
| Overflow control | No | Yes |
| Strict floating point evaluation | Yes; opt-in/out | No |
| Local classes | Yes | No |
| Ad-hoc (anonymous) classes | No | Yes |
| Verbatim (here-)strings | No | Yes |
| Exceptions | Java | C# |
| Checked exceptions | Yes | No |
| Try-catch-finally | Yes | Yes |
| Arrays and collections | Java | C# |
| One-dimensional, zero-based index arrays | Yes | Yes |
| Rectangular (multidimensional) arrays | No | Yes |
| Jagged (arrays of arrays) arrays | Yes | Yes |
| Non-zero based arrays | No | Some |
| Unified arrays and collections | No | Yes |
| Maps/dictionaries | Yes | Yes |
| Sets | Yes | Yes |
| Lists/vectors | Yes | Yes |
| Maps | Yes | Yes |
| Queues/stacks | Yes | Yes |
| Bags/multisets | Yes | Yes |
| Metadata | Java | C# |
| Metadata annotations/attributes | Interface based | Class based |
| Positional arguments | No; unless a single argument | Yes |
| Named arguments | Yes | Yes |
| Default values | At definition | Through initialization |
| Nested types | Yes | Yes |
| Specialization | No | Yes |
| Conditional metadata | No | Yes |
| Preprocessing, compilation and packaging | Java | C# |
| Namespaces | Packages | Namespaces |
| Packaging | Package | Assembly |
| File contents | Restricted | Free |
| Conditional compilation | No | Yes |
| Custom errors/warnings | No | Yes |
| Explicit regions | No | Yes |
| Threading and synchronization | Java | C# |
| Native interoperability | Java | C# |
| External/native methods | Yes | Yes |
| Marshalling | External glue code required | Yes; metadata controlled |
| Pointers and arithmetics | No | Yes |
| Native types | No | Yes |
| Fixed size buffers | No | Yes |
| Explicit stack allocation | No | Yes |
| Address pinning (fixing) | No | Yes |
| Address-of | No | Yes |
| Object pinning (fix variable to address) | No | Yes |
| Source:wikipedia |
