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| Compatible with [[C (programming language)|C]] source code, except for a few [[corner case]]s.
| Provides the [[Java Native Interface]] as well as [[Java Native Access]] and more recently [[Java Native
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| [[Write once, compile anywhere]] (WOCA).
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| [[Resource management (computing)|Resource management]] can be done manually or by automatic lifetime-based resource management ([[Resource Acquisition Is Initialization|RAII]]).
| Resource management must generally be done manually, or automatically via finalizers, though this is generally discouraged. Has try-with-resources for automatic scope-based resource management (version 7 onwards). Resources, such as memory, can be managed using [[Java Native Interface]] or the Java Foreign Function and Memory API (since Java 22), but requires calling external C/C++ code.
It can also be done using the internal API <code>sun.misc.Unsafe</code> but that usage is highly discouraged and will be replaced by a public API in an upcoming Java version.
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| Supports classes, structs ([[passive data structure]] (PDS) types), and unions, and can allocate them on the [[Dynamic memory allocation|heap]] or the [[Stack-based memory allocation|stack]].
| Classes are allocated on the [[Dynamic memory allocation|heap]]. [[Java version history#Java SE 6|Java SE 6]] optimizes with [[escape analysis]] to allocate some objects on the [[Stack-based memory allocation|stack]].
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| Allows explicitly overriding types, and some implicit narrowing conversions (for compatibility with C).
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| [[Operator overloading]] for most operators. Preserving meaning (semantics) is highly recommended.
| Operators are not overridable. The language overrides + and += for the <code>String</code> class.
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| Single and [[multiple inheritance]] of classes, including virtual inheritance.
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| Compile-time templates. Allows for [[Turing complete]] meta-programming.
| [[Generics in Java|Generics]] are used to achieve basic type-parametrization, but they do not translate from source code to byte code due to the use of [[type erasure]] by the compiler. Java type-casts all generics to their lowest bound (<code>Object</code> if no such bound exists, otherwise <code>? extends T</code> is casted to <code>T</code>).
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| Function pointers, function objects, lambdas (in [[C++11]]), and interfaces (using abstract classes).
| Functions references, function objects and lambdas were added in [[Java 8]]. Classes (and interfaces, which are classes) can be passed as references as well through <code>SomeClass.class</code> and <code>someObject.getClass()</code>.
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| No standard inline documentation mechanism. Third-party software (e.g. [[Doxygen]]) exists. Standard library vendors may provide documentation comments, though it is not guaranteed.
| Extensive [[Javadoc]] documentation standard on all system classes and methods.
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| <syntaxhighlight lang="cpp">
class Foo { // Declares class Foo
private:
int x = 0; // Private Member variable. It will
// be initialized to 0, if the
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* Java has both language and standard library support for [[Thread (computer science)|multi-threading]]. The <code>synchronized</code> [[Java keywords|keyword in Java]] provides [[mutual exclusion|mutex locks]] to support multi-threaded applications.{{sfn|Goetz|Peierls|Bloch|Bowbeer|2006|loc=§2.3.1 Intrinsic locks|pp=25-26}}{{sfn|Bloch|2018|loc=Chapter §11 Item 78: Synchronize access to shared mutable data|pp=126-129}} Java also provides libraries for more advanced multi-threading synchronizing. [[C++11]] has a defined memory model for multi-threading in C++, and library support for creating threads and for many synchronizing primitives. There are also many third-party libraries for this.
* C++ member functions can be declared as [[virtual function]]s, which means the method to be called is determined by the run-time type of the object (a.k.a. dynamic dispatching). By default, methods in C++ are not virtual (i.e., ''opt-in virtual''). In Java, methods are virtual by default, but can be made non-virtual by using the <code>[[final (Java)|final]]</code> keyword (i.e., ''opt-out virtual'').
* C and C++ enumerations are primitive types.
* Unary operators {{code|++}} and {{code|--}}: in C++ "The operand shall be a modifiable [[Value (computer science)|lvalue]]. [skipped] The result is the updated operand; it is an lvalue...",<ref>Standard for Programming Language C++ '11, 5.3.2 Increment and decrement [expr.pre.incr].</ref> but in Java "the binary numeric promotion mentioned above may include unboxing conversion and value set conversion. If necessary, value set conversion {and/or [...] boxing conversion} is applied to the sum prior to its being stored in the variable.",<ref>The Java™ Language Specification, Java SE 7 Edition, Chapters 15.14.2, 15.14.3, 15.15.1, 15.15.2, http://docs.oracle.com/javase/specs/</ref> i.e. in Java, after the initialization {{code|1=Integer i=2; ++i;|2=java}} changes the reference {{code|i}} by assigning new object, while in C++ the object is still the same.
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