9 Key Differences Between Java and C++

Before we discuss the differences between Java and C++, here is a short history of the two languages.


Java was originally designed for the television industry, ITV (Interactive Television) to be exact. The intent was to allow the user to interact with the TV in various ways such as sending feedback messages to the broadcaster, controlling the TV using tablets/phones, etc. Unfortunately, the programming language was a bit too sophisticated for that industry at that time so James Gosling (a.k.a. the father of programming) alongside Mike Sheridan, and Patrick Naughton, collectively known as the Green Team started a project to create the Java Programming Language. The language was first named Greentalk then later changed to Oak and finally Java as we know it today.


C++ began when Bjarne Stroustrup was working on his PhD thesis.  He worked with a language called Simula which is known to be the first language that used the OOP paradigm. Simula was quite slow for what Stroustrup needed to do so he started working on C  then later added functionalities which were key to his project to the language and named it C++.

Below are some of the key differences between Java and C++ to keep in mind when selecting a Programming Language to develop your Software Application.

1. Platform Dependance

A platform dependent application is one that requires a specific operating system / hardware to work while a platform independent application will work on any operating system / hardware without needing further manipulation. The manipulation that is usually needed is the recompilation of the program into Bytecode which is what runs on the  underlying hardware or operating system. Java compiles to Bytecode which can be run on any platform making it platform independent while C++ compiles to Machine Language which is hardware specific and needs to be recompiled to run on other machines, making it platform dependent.

2. Use

Java is mainly used for application programming while C++ is used for both application programming (e.g. Games development, facial recognition or any application that is memory and speed intensive) and for more low-level programming where there is a need to be closer to the hardware. C++ is a powerful, highly expressive and extremely robust language i.e. it’s easy to write code that can be understood by both the compiler and the developer.  Java is very high-level and robust in it’s own ways. As a dev, there are generic things that you would want your application to be able to handle and core functionality will most likely be generic across certain applications. If there is a language that caters for the core functionalities you need, it would be a good idea to use it instead of writing the functions yourself.

Context is everything, have a good understanding of your problem before you pick a programming language for your solution.

3. Learning Curve

Java runtime libraries are bigger and offer more support to the developer. Java has many tools you can use to write code, multiple IDE’s with great debugging support and a wide community you can reach out to when you are stuck. More people write Java and it’s in demand in the market vs C++ so community support from that perspective is arguably wider. Since Java is more high-level it can be easier to grasp and understand. On the other hand, c++ has a few overheads that might be overwhelming to new developers.

4. Memory Management

Java has automated Memory Management. The programmer does not have to manually de-allocate or clean up memory which is no longer needed. Java uses a Garbage Collector to clean up the unused/unneeded memory on behalf of the developer. C++ does not have automated Memory Management. The onus is on the developer to manage memory and avoid memory leaks and over-allocation of memory. Java is a memory-safe language so, an attempt to assign values outside of the given array parameters throws an error. C++ is much more flexible, but this comes at a price. C++ will allow the programmer to assign values outside of the allocated memory resources. This can introduce bugs which may be difficult to find and also cause runtime crashes.

5. Overloading

This is a way of increasing the readability of your code. Overloading keeps the method name the same and the logic, number of arguments and data types are altered. Java only allows for method overloading while C++ allows both method overloading as well as operator overloading. Operator overloading changes the function of an operator(e.g. ++, –, *) and occurs at compile-time while method overloading occurs at run-time.

6. Function Calls

Functions which take arguments are called in two different ways: Call by Reference (Pass by Reference) and Call by Value. The former receives the address (reference) of a variable as an argument to the function. The latter passes the values of the arguments which are stored or copied into the formal parameters of the function and the values remain unchanged. Pass by Reference saves memory because you don’t have to pass in the actual value but rather its memory address. Also, you will not need copies of the values being passed.

7. Inheritance

Inheritance in programming is a way of propagating some base functionality where all objects which inherit from the parent object, carry with them the behaviour of the parent. Java does not support inheritance through classes. It uses an interface instead to support multiple inheritance. C++ supports multiple inheritance through classes. The advantage is that you are able to model complex relationships through the inheritance of base functionalities of multiple classes. However, you should look out for issues such as the diamond problem where a subclass gets multiple copies of the same super class.

8. Pointers

C++ allows the developer to manage and manipulate values in memory spaces directly while Java doesn’t. This allows for different function calls discussed in point number 6 (Call by Reference and Call by Value). Direct access to the memory space allows Pass by Reference in C++. Pointers can be beneficial in instances where large datasets need to be manipulated in memory so, instead of moving the data around, you can point to the location where the data is stored. This generally saves memory and increases the speed of your program.

9. Extra Abstraction

Often, when building large scale applications, there is a need to write code that can handle different data types. In Java, this is referred to as Generics while in C++, this is called Templates.  Generics and Templates adds extra abstraction to your code which makes your code much easier to read and robust.


It is very important to know which language to use to efficiently solve a specific problem. Many new developers often struggle to pick a language be it for learning or for a solution to a problem. It is important to note that once you choose a language for your software development project, you’re basically tied to that language until you complete your project, except in instances where you are creating a throw-away prototype. Even then, you want to ensure that the language you pick will allow you to implement your solution as easily and efficiently as possible.

I trust that the above points have shed some light with regards to the differences between Java & C++.

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