Editing Comparison of Java and C++ (section)

=== Runtime ===
{| class="wikitable"
! style="width:50%;"| C++
! style="width:50%;"| Java
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| C++ is compiled directly to [[machine code]] which is then executed directly by the [[central processing unit]]. 
| Java is compiled to [[byte-code]] which the [[Java virtual machine]] (JVM) then [[interpreter (computing)|interprets]] at runtime. Actual Java implementations do [[just-in-time compilation]] to native machine code.
|-
|}
* Due to its unconstrained expressiveness, low level C++ language features (e.g. unchecked array access, raw pointers, [[type punning]]) cannot be reliably checked at compile-time or without overhead at run-time. Related programming errors can lead to low-level [[buffer overflow]]s and [[segmentation fault]]s. The [[Standard Template Library]] provides higher-level RAII abstractions (like vector, list and map) to help avoid such errors. In Java, low level errors either cannot occur or are detected by the [[Java virtual machine]] (JVM) and reported to the application in the form of an [[exception handling|exception]].
* The Java language requires specific behavior in the case of an out-of-bounds array access, which generally requires [[bounds checking]] of array accesses. This eliminates a possible source of instability but usually at the cost of slowing execution. In some cases, especially since Java 7, [[compiler analysis]] can prove a bounds check unneeded and eliminate it. C++ has no required behavior for out-of-bounds access of native arrays, thus requiring no bounds checking for native arrays. C++ standard library collections like std::vector, however, offer optional bounds checking. In summary, Java arrays are "usually safe; slightly constrained; often have overhead" while C++ native arrays "have optional overhead; are slightly unconstrained; are possibly unsafe."