November 21, 2019   |   6min read

Java vs Python: Comparative Analysis of the Best Programming Languages

Java vs. Python—An introduction

Java and Python are two of the most popular programming languages right now. According to the Tiobe index, Java ranks #1 while Python is #3.

Both rank in the top 5 technologies among developers in the StackOverflow 2019 survey, in which 90,000 users took part. If you exclude non-programming languages from the survey, then Python is #2 and Java #3, both giving place only to the #1 JavaScript.

To top it off, the same podium of language popularity is visible on Github—the most popular open-source software repository on the Internet, where JavaScript, Java, and Python rank highest.

Even though JavaScript is nowadays more and more present on the server-side thanks to the rise of NodeJS, it is safe to say that most of its uses are still on the front end in the browsers. All this leads to the conclusion that Java and Python are the most popular solutions for server-side applications right now.


Both languages have been created in the early ‘90s, with the first initial release of Python 0.9 in 1991 and the first public implementation of Java 1.0 available in 1996.

The histories behind their creations are quite different, however. Python was conceived by one man, Guido van Rossum, a Dutch computer scientist. He was looking for a language with a simple syntax to use in his current project. He published the 0.9 version on the Usenet, an early internet forum. From then on, he has worked on Python for over 20 years along with other programmers in the open-source model, meaning anyone could read Python’s code and contribute to it.


Java, on the other hand, was created by a small team within a megacorporation—Sun Microsystems. They had been manufacturing hardware for some time and wanted to enter the market with a small handheld tablet device which would control all of the home’s entertainment systems. The team working on this project decided to create a new language with automatic memory management and capable of running on different devices, unlike the then-popular C and C++. Led by James Gosling, they created Java. Even though the handheld device called Star7 never took off, Java evolved to become one of the major programming languages of the last 25 years.


There are several similarities between Java and Python in terms of technological characteristics.

Automatic memory management

First of all, both languages offer automatic memory management. This means that programmers don’t have to allocate and deallocate memory in the code manually; what is the case, for example, in C and C++. Instead, the language runtimes do this themselves. In Java, memory is managed by the Java Virtual Machine (JVM) where all Java programs run. In Python, it’s the Python memory manager.

Compiled or interpreted?

There’s a popular opinion that Java is a compiled language, and Python is an interpreted language (compiled “on the fly” while being executed). This is, in fact, only partly true.

Java is compiled to an intermediary format called the byte code ahead of time (before the execution). Then, while executed, the byte code is interpreted into machine code. However, the Python interpreter also processes .py modules into a binary .pyc form before the execution. So you could say that both of them are bytecode interpreted languages.


Static vs. dynamic typing

Now, let’s look at the differences between Java and Python. The most prominent difference between the two is that Java is a statically-typed language, while Python is a dynamically-typed language.

It means that in Java you have to explicitly state what the type of each variable in your code is. This slightly changed in Java 10, which includes the “var” keyword, where, in some cases, the compiler can infer the variable type for you.

Static typing allows detecting many errors during the compilation time and usually results in a readable codebase. Nevertheless, it leads to a more rigid and verbose code, which many programmers dislike.


On the other hand, in Python, you don’t declare types of variables. They have no type; rather, it’s the values that have a type. What this means is that you can declare a variable “foo” and assign it the integer value of “1,” and a few lines further you can re-assign it to hold the string value of “bar.” Python won’t complain. But your program can explode at runtime :)

Dynamically-typed languages usually allow you to create code more quickly. Moreover, it can be more “frivolous,” but at the cost of potential runtime errors and limited readability. (“What type is this value again?”—asks a programmer new to a legacy codebase).

To mitigate this, projects in dynamically-typed languages usually contain a lot of unit tests, validating the contents of variables to prevent runtime errors.

It’s worth mentioning that in newer versions of Python, you can use type hints, which allow you to create a “sort of” statically typed code with some checks performed by static code analyzers, but no runtime checks are enforced.

The syntax

Java follows the C-like syntax style, meaning many brackets “{}” and semicolons “;”. On the other hand, Python has an indentation-based syntax, meaning blocks of code are separated by indentations in the text. Python also uses only a few non-alphabetic characters and usually reads pretty much like the English language.

Java Virtual Machine

As I already mentioned above, Java code is compiled to Java Bytecode and run in a JVM—Java Virtual Machine. The fact that there is this intermediary bytecode allowed the implementation of other languages apart from Java, which can also compile to bytecode and be run in the JVM. The most popular of those include Groovy, Scala, Kotlin, and Clojure. This enabled a pretty big and robust “JVM ecosystem,” where common libraries and frameworks can be shared and support many of the JVM languages with no modifications.

No similar ecosystem exists in the “Python world.”


Neither of the two is the most efficient language on the planet in terms of performance. However, in most use cases, nowadays, the language-level performance is negligible—the bottlenecks usually lie somewhere else, e.g., in the database connections. Moreover, if you create a web application, you also usually add caching, so you offload the code usage this way.

All in all, unless you’re building low-level embedded software, neither Java nor Python’s performance shouldn’t be a problem for you.



Java is mostly used on the server-side of medium and large web applications, usually with the use of JavaEE or Spring Framework. It is commonly used in large corporate software projects, such as banking or other financial systems, due to its stability and performance over the years. Historically, it has been present in many embedded systems in devices such as DVD or Blu-ray players.

Moreover, it is one of the main languages for Android programming, alongside Kotlin. Many teenagers also use Java to create plugins and mods for their beloved game, Minecraft, which has also been written in this language.

Python is also very present in web applications, however mostly in the small to medium ones, with the use of Django or Flask frameworks. Its dynamic nature makes it rather unsuited for large products.

However, Python is also widely used in the rapidly growing Machine Learning and AI field. With frameworks such as Tensorflow, PyTorch, or Scikit, it enables data scientists to build and train their models. Moreover, it is used in the scientific community for research purposes and data analytics, with Pandas, NumPy, or SciPy libraries enabling advanced computations.

Finally, Python is also often the language for teaching programming. It is, for example, the basic language for the Raspberry Pi microcomputer, often used by students all over the world because of its simplicity and low price.


Both Java and Python have been there for a long time and offer robust and battle-tested technologies. Which one to choose for your next project will mostly depend on the characteristics of the project and the preferences of your development team.

At Polidea, we enjoy creating awesome projects using either of those languages. If you’re unsure which one to choose, make sure to contact us or drop in for coffee, and we can dive deep into the needs of your company and help you make the right choice ;)

Szymon Przedwojski

Senior Software Engineer

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