Comparison of Java and C++: Difference between revisions

Revision as of 05:11, 4 February 2025

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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++ enumerations are primitive types and support implicit conversion to integer types (but not from integer types). Java enumerations can be <{{code>|public static enum{enumName1,enumName2}</code>|java}} and are used like classes. Another way is to make another class that extends <code>java.lang.Enum<E></code>) and may therefore define constructors, fields, and methods as any other class. As of [[C++11]], C++ supports [[C++11#Strongly typed enumerations|strongly-typed enumerations]] which provide more type-safety and explicit specification of the storage type.

* 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.

=== Resource management ===