Difference Between C++ and Java

C++ and Java are most commonly used programming languages. Java has a strong influence of C++ as it was developed after C++ and both support OOP (Object Oriented Programming) paradigms. The crucial difference which differentiates both of the programming languages is that C++ is platform dependent while Java is platform independent.

Java source code is converted into bytecode when compiled. At runtime, the interpreter executes this bytecode and gives output. Mostly Java is an interpreted language and therefore platform independent. On the other hand, C++ uses a compiler to compile and run the source code. It converts source code into machine level language; hence C++ is platform dependent.

Content: C++ Vs Java

1. Comparison Chart
2. Definition
3. Key Differences
4. Conclusion

Comparison Chart

Basis for comparison	C++	Java
Platform dependency	Dependent	Independent
Memory management	Accessible to programmer	System controlled
Inheritance model	Single and multiple inheritance,	Single inheritance with abstract interfaces.
Polymorphism	Explicit per method, encourages mix-in hierarchies.	Automatic
Access control and object protection	Thorough and flexible model with constant protection available.	Cumbersome model encourages weak encapsulation.
Portability	Source must be recompiled for platform, hence code is not portable.	Bytecode classes portable to platform specific JVM's.
Type semantics	Consistent between primitive and object types.	Differs for primitive and object types.
Program organisations	Functions and data can reside external to any class, global (file) and namespace scopes available.	All function and data exist within classes, package scope available.
Libraries	Predominantly low-level functionality	Massive, classes for high-level services
Runtime error detection	Programmer responsibility	System responsibility
Supports	Pointers, structure and union.	Threads and interfaces.

Definition of C++

C++ was developed with the intent of extending the procedural C language to include OO capabilities. C++ language syntax is the superset of C. In C++ certain units are object type, and several are traditional primitive types, hence it a hybrid language. It is sometimes inconsistent with pure OO programming such as free-standing functions, because of its origin. Nevertheless, syntax and semantics remain stable across native and object data types.

Generalization with inheritance is assisted by C++ and runtime method resolution and allows multiple inheritance. Classes may include combination of polymorphic and non-polymorphic methods. A superclass must explicitly declare the particular method as virtual to enable runtime resolution for that method. This implementation is typically achieved by having each object contain a pointer to a table of the method to its class. It does not have shared basic object type as characterizes other OO languages.

Method and function overloading is supported by C++ where they share the same name but have parameters that vary in number or type. Access specifiers are used to promote encapsulation by restricting the availability of class members (methods or data) in three ways: to methods of the class itself (private), the class and its subclasses (protected), or any class/method/function (public). All the restrictions are performed on classes no on the objects. C++ namespace provides a semantic scope for symbols but doesn’t affect the accessibility of visible entities.

Memory management in C++

C++ exposes its memory management to the programmer, which facilitates customizable memory allocation strategies. The objects (primitive or class types) that are declared at compile time assigned with static storage by the compiler. The new operation is used for obtaining dynamic storage from the heap at runtime which should be explicitly deleted using delete operation while not used. Memory addresses remain fixed for the lifetime of an object. It does not offer run-time error detection facilities.

Definition of Java

Java is also an object-oriented programming language and every java program is defined as a class. It is portable and device- independent language. After that, restricted java program was incorporated into web browsers to allow dynamic and interactive contents on web pages. Java’s prevalence comes from the enormous library of associated classes and its portability. The source code is compiled to an intermediate bytecode by java compiler, which in succession runs on a platform-specific Java Virtual Machine. JVMs are readily available for all operating systems and substitutable with JVM’s from other vendors.

Java also has distinctive primitive and object types and is a strongly typed language. It does not reference syntax for primitives but does provide tools for converting primitives and corresponding object types, for example, int and integer. Some versions of Java also include autoboxing, where the primitives and their corresponding wrappers, are automatically converted.

Every java object types are at the extreme abstract level, the reason is that they share type compatibility with a single Object ancestor. If false downcasts are used the exceptions is thrown by Run-time type checking. Polymorphism is automatic, and it can be prevented when the definition of overriding methods are explicitly prohibited. Only single inheritance is supported by java, even though interfaces can emulate multiple superclasses.

Packages are responsible for organizing the classes and providing scope for identifiers. Same as C++ access specifiers, Java access modifiers restrict the availability of attributes and methods, private provides intraclass access, public provides universal access and protected extends access to subclasses defined exterior to their parent class’s package. Although, java meaning of protected is a bit different than C++.

Memory management in Java

Memory management is the province of the JVM. The Java code (data and methods) remains within the context of a class. A garbage collector is used for object deallocation, the system returns object memory to its pool when the object is not useful anymore. Java also provides runtime memory error detection and when detected  it throws appropriate exceptions.

Conclusion

Both C++ and Java programming languages support OOP paradigms but there exist nuances and differences between them. C++ is a flexible language emphasizes on the runtime efficiency and can form broad type hierarchies. It is a platform offered for maintaining uniform semantics, fine granularity of expression, and control with simplicity.

On the other hand, Java emphasizes security and portability at the cost of efficiency and flexibility. Java provides abstract interfaces to imitate multiple inheritance, differentiate between object and primitive type semantics. It also offers a huge library of objects for general and distributed platform implementation.