Comparing programming languages is always a touchy subject among developers. While you could have a relatively balanced discussion about the differences between R and Python, that may not be the case for Python and Java. Both languages have rich and similar growth histories and are often the first programming language that many developers learn.
When these two or any other languages are concerned, it is hard to find unbiased opinions. And, as my first language is Python, you may not agree with some of the differences I share in terms of ease of use, syntax, and readability. But other than that, prepare for a comprehensive fact-based rundown of the differences between Python and Java in nine key areas.
1. Python vs Java: Use Cases and Industry Adoption
Let’s start by comparing where and why both languages are used because that’s probably the first question beginners ask before deciding between the two. Choosing one may decide what kind of a developer they will eventually be.
First of all, both are general-purpose languages, meaning you can build nearly anything in Java or Python. The big question is, “How good are they at each thing?”
Python is the king when it comes to creating AI applications and machine learning models as well as stunning data plots. For example, most algorithms you interact with daily on Instagram, TikTok, or LinkedIn are probably written in Python.
Python is also popular in backend web development with frameworks like Django and Flask, in addition to AI and data. It is also widely used in academia for scientific computing as it is easy for researchers with no background in programming to pick up.
On the other hand, you will see Java used in enterprise massive-scale applications due to its robustness and security. If you use Android, many of the apps on your phone may have Java brains.
Java’s security and stability make it an ideal choice for banks and other financial institutions for their backend systems. I mentioned Python was the king in the world of AI and data, but some key big data technologies like Hadoop and Apache Spark are written in Java because it is much faster.
While there’s significant overlap in their capabilities, the choice between Python and Java often comes down to the specific requirements of the project, the existing technology stack of the organization, and the available expertise in the development team.
2. Learning Curve and Ease of Use of Python and Java
Most people you talk to will say that Python is much easier to learn for beginners because it reads like English and uses fewer words, so your code will be shorter and more readable. Meanwhile, Java enforces strict syntax and OOP concepts from the very beginning, which may provide a highly unpleasant experience for newcomers. So, the clear winner in terms of the learning curve is Python. But how about ease of use?
One way to look at this is the trade-off between immediate and delayed gratification. In Python, you start enjoying programming straight away because its syntax is intuitive and short. But you don’t realize that this fun and easy syntax comes at the cost of sacrificing good programming practices (the type system comes to mind, but more on that later).
If you start your programming journey with Java, each of your learning sessions will feel like a brain workout. To put on programming muscle and develop skills, you have to sweat (and swear) a lot because Java forces you to use static typing and follow OOP principles, which are concepts Python developers learn (or start caring about) at the advanced level.
So, in Python, you have an easy time in the beginning but may struggle with bad habits developed early in your journey in serious projects. Java’s complexity may lead to a steeper initial learning curve, but it will definitely provide you with a deeper understanding of programming concepts in the long run.
3. Java vs Python: Syntax and Readability
It is at this point that anything I might have said in Java’s favor loses all meaning, and you go running toward Python.
The above example shows how to perform a very common operation in both languages: reading a text file. Java calls for a staggering 18 lines of code, whereas Python only requires four lines. So, why is its syntax so verbose?
The number one contributor to word count in Java code is Java’s strict type system. Every variable, method parameter, and return value must be explicitly declared with its type. This verbosity, while sometimes seen as cumbersome, provides clarity and helps catch type-related errors at compile-time rather than runtime.
In contrast, Python uses dynamic typing, which allows for more concise code but can sometimes lead to type-related bugs that only surface during execution. This is a huge problem because you might have a complex script run for an hour and at line 246, you encounter a type error, breaking the whole execution (it happens).
Java also uses a lot of curly braces and semi-colons, further contributing to its unreadability. The purpose of curly braces is the declaration of blocks of code. Every function, class, loop, and conditional statement in Java is enclosed in curly braces. While this explicit structure can help organize code, it can make the code appear cluttered, especially to beginners.
Semi-colons are used to terminate statements, which adds another layer of syntax that Python doesn’t require. These elements, combined with the verbose type declarations, make Java code generally longer and potentially more challenging to read at a glance compared to Python’s cleaner, more concise syntax, which relies on white space to define code block hierarchy.
4. Type System in Python and Java
Python’s dynamic type system is the aspect of the language that most programmers complain about. In dynamic typing:
Variable types are determined at runtime
Variables can hold different data types throughout the program’s execution
Type checking occurs during run time
No need to declare variable types explicitly
5. Python vs Java: Performance and Execution
Now comes Python's slow performance, which many developers dislike. In fact, Python is among the turtles of programming languages.
It compares more than 25 programming languages in terms of speed and energy consumption and Python is at the bottom in both criteria while Java is in the top five. So, what is the reason for such a huge discrepancy in the performances of these languages?
Well, one of the main reasons for Python’s slow execution is its use of an interpreter rather than a compiler. An interpreted language executes code line by line at runtime, while a compiled language translates the entire program into machine code before execution. This interpretation process adds overhead to Python’s execution, making it slower compared to compiled languages like Java.
Additionally, dynamic typing in Python slows down performance despite its flexibility. The interpreter needs to check types at runtime, which adds extra processing time. In contrast, Java’s static typing allows for more optimizations at compile time, resulting in faster execution.
Another factor is Python’s Global Interpreter Lock (GIL), which limits true multi-threading capabilities in CPython (the standard Python implementation). This can hinder performance in multi-core systems, whereas Java can more effectively use multiple cores.
However, it’s important to note that Python’s ease of use and rapid development capabilities often outweigh its performance drawbacks for many applications, especially when raw processing speed isn’t the primary concern.
6. Object-Oriented Programming (OOP) Features
Both Python and Java are object-oriented programming languages (OOP is a programming paradigm that organizes software design around data or objects rather than functions and logic) but they implement OOP concepts in different ways. Let’s explore the key differences.
Class definition and object creation
In Python, classes are defined using the class keyword, and the constructor is defined using __init__. Objects are created by writing the class name with brackets (obj = Car()). Java, on the other hand, requires classes to be defined in separate files (one public class per file). Constructors in Java have the same name as their class, and objects are created using the new keyword.
